Manual Stihl MS 241 C-M (page 172 of 174) (English)

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STIH)

STIHL MS 241 C

2010-11

1MS 241 C

RA_741_00_01_01

1. Introduction and

safety precautions 3

1.1 Introduction 3

1.2 Safety precautions 4

2. Specifications 5

2.1 Engine 5

2.2 Fuel system 5

2.3 Ignition system 5

2.4 Chain lubrication 5

2.5 Tightening torques 6

3. Troubleshooting 8

3.1 Clutch 8

3.2 Chain Drive,

Chain Brake,

Chain Tensioner 9

3.3 Chain lubrication 11

3.4 Starter 12

3.5 Ignition system 14

3.6 Carburetor 15

3.7 Engine 18

4. Clutch 19

4.1 Clutch drum 19

4.2 Clutch 19

5. Chain brake 20

5.1 Checking operation of

chain brake 20

5.2 Brake band 20

5.3 Brake lever 21

5.4 QuickStop Super

brake lever 23

5.4.1 Adjusting brake cable 25

5.4.2 Brake cable

Removal and

installation 27

5.5 Cam lever 28

5.6 Pins 29

5.7 Chain tensioner 31

5.7.1 Quick chain

tensioner 31

5.7.2 Chain catcher 32

5.8 Bar mounting stud 32

5.9 Collar nut for chain

sprocket cover 32

6. Engine 34

6.1 Muffler 34

6.2 Leak testing 35

6.2.1 Preparations 35

6.2.2 Vacuum test 36

6.2.3 Pressure test 36

6.3 Oil seals 37

6.3.1 Ignition side 37

6.3.2 Clutch side 37

6.4 Shroud 38

6.5 Cylinder 39

6.6 Crankshaft 41

6.6.1 Ball bearing /

crankcase 46

6.7 Piston 47

6.8 Piston rings 49

6.9 Decompression valve 50

7. Ignition system 51

7.1 Ignition timing 51

7.2 Pre-separator 51

7.3 Control unit 51

7.4 Spark test check

control unit 54

7.5 Spark plug boot 55

7.5.1 Ignition lead 56

7.6 Flywheel 56

7.7 Short circuit wire 57

7.7.1 Contact test 57

7.7.2 Removal and

installation 57

7.7.3 Ground wire 64

7.7.4 Contact spring 64

7.8 Troubleshooting,

ignition system 66

8. M-Tronic 69

8.1 Calibrating the

control unit 69

8.2 Testing 70

8.2.1 Test preparations 70

8.2.2 Connect the test lead 70

8.2.3 Check screwed and

plug connections

as well as switch 70

8.2.4 Checking the

solenoid valve 72

8.2.5 Checking the start

detection function 73

8.2.6 Checking the wiring

harness 74

8.3 Wiring harness 76

8.4 Switchgear 76

8.5 Troubleshooting,

M-Tronic 80

8.5.1 Engine does not start 80

8.5.2 Engine does not start

in position } 81

8.5.3 Engine speed drops

under load

– low power 82

8.5.4 Ignition –

no ignition spark 83

8.5.5 Engine stops

suddenly 84

8.5.6 Cut-off speed

not reached 85

9. Rewind starter 86

9.1 General 86

9.2 Fan housing 86

9.3 Pawls 87

9.4 ErgoStart 88

9.5 Rope rotor 89

9.6 Starter rope /

starter grip 89

9.7 Tensioning the rewind

spring 90

9.8 Replacing the rewind

Spring 91

Contents

2 MS 241 C

Contents

10. Maintaining the

antivibration

elements 94

10.1 Antivibration element

on oil tank 94

10.2 Antivibration element

on fuel tank 94

10.3 Antivibration element

on front handle 96

10.3.1 Antivibration element

on handlebar, version

with heating 97

10.3.2 Stop buffer 98

10.3.3 Filter base buffers 98

10.4 Front handle 99

10.4.1 Handlebar with

heating 100

11. Actuating levers 105

11.1 Master Control lever 105

11.1.1 Removal and

installation 105

11.2 Throttle trigger / throttle

trigger interlock 106

11.3 Throttle trigger /

throttle trigger interlock /

QuickStop Super 107

11.3.1 Trigger switch

QuickStop Super 108

11.3.2 Trigger interlock

QuickStop Super 109

11.4 Choke rod 110

11.5 Throttle rod 110

12. Chain lubrication 112

12.1 Pickup body 112

12.2 Oil suction hose 112

12.3 Oil pump 112

12.4 Valve 114

13. Fuel system 115

13.1 Air filter 115

13.2 Baffle 115

13.3 Filter base 115

13.4 Air guide shroud 117

13.4.1 Air guide shroud,

versions with manual

fuel pump 120

13.4.2 Air guide shroud

version with heating 123

13.5 Carburetor 129

13.5.1 Leakage test 133

13.6 Repairing the

carburetor 133

13.6.1 Metering diaphragm 134

13.6.2 Inlet needle 135

13.6.3 Pump diaphragm 135

13.6.4 Lead retainer 137

13.6.5 Lever of the

throttle shaft 137

13.6.6 Lever of the

choke shaft 138

13.7 Carburetor

adjustment 138

13.8 Carburetor bracket 138

13.9 Intake elbow 140

13.10 Tank vent 141

13.10.1 Testing 141

13.10.2 Removal and

installation 142

13.11 Fuel intake 143

13.11.1 Pickup body 143

13.11.2 Fuel hose 143

13.11.3 Fuel hoses manual

fuel pump 146

13.11.4 Manual fuel pump 148

13.11.5 Tank housing 149

14. Heating 152

14.1 Carburetor heating 152

14.1.1 Check overall system 152

14.1.2 Check heating

element 152

14.1.3 Thermostatic switch 153

14.2 Troubleshooting,

carburetor heating 154

14.3 Handle heating

systems 155

14.3.1 Troubleshooting 155

14.4 Heating switch 156

14.5 Heating element

in handle 158

14.6 Heating element in

front handle 159

14.7 Generator 160

14.7.1 Troubleshooting chart,

handle heating systems

and generator 162

14.7.2 Summary of test

connections and test

values 164

14.8 Wiring harness 166

14.9 Connecting leads

heating elements 167

15. Special tools 170

16. Service

accessories 172

3MS 241 C

1. Introduction and safety precautions

1.1 Introduction

This Service Manual contains

detailed descriptions of all the

typical repair and servicing

procedures for this machine.

Refer to the illustrated spare parts

lists during all repair work. These

lists show the installation position

and order in which the individual

parts and modules should be

assembled.

Refer to the latest edition of the

relevant spare parts list to check the

part numbers of any spare parts

required.

A fault on the machine may be due

to several causes. To help locate

the fault, consult the chapter on

"Troubleshooting" and the

"STIHL Service Training System"

for all functional groups.

Refer to the "Technical Information"

bulletins for engineering changes

which have been introduced since

publication of this Service Manual.

Technical information bulletins also

supplement the spare parts list and

Service Manual until an updated

edition is issued.

The special tools mentioned in the

descriptions are listed in the chapter

"Special Servicing Tools" of this

manual. The tools can be identified

according to part number in the

"STIHL Special Tools" manual. The

manual lists all tools supplied by

STIHL.

Symbols are included in the text and

pictures for greater clarity.

The meanings are as follows:

In the text:

N Action to be taken as shown in

the illustration above the text

– Action to be taken that is not

shown in the illustration above

the text

In the illustrations:

A Item pointer (short)

a Direction of

movement (long arrow)

@ 4.2 Reference to another

chapter, in this case to

Chapter 4.2

Service Manuals and technical

information bulletins are intended

exclusively for the use of properly

equipped repair shops. They must

not be passed on to third parties.

Servicing and repairs are made

considerably easier if the machine

is mounted on assembly stand (3)

5910 890 3101. For this purpose,

secure the clamp (2)

5910 850 1650 to the assembly

stand with two screws (1).

The screws must not protrude, as

they may damage the housings

when clamping the machine,

depending on the machine.

The machine is guided with the

collar screw through the upper hole

of the clamping rail and fastened

using nut M 8 (arrow).

The machine is fastened to the

mount on the clamping rail by the

screw head on the crankcase.

2710RA320 TG

2410RA000 TG

4 MS 241 C

Preparing to make repairs

Before repair tasks or clamping on

the assembly stand, always remove

the chain sprocket cover, saw chain

and guide bar.

Always use original STIHL

replacement parts.

They can be identified by the STIHL

part number

the logo {

and the

STIHL parts symbol K

The symbol may appear alone on

small parts.

Storage or disposal of oil and fuel

Collect fuel or lubricating oil in

a clean container and dispose of it

in accordance with environmental

regulations.

Plug connections on electrical

leads

The insulating tube must be

oriented so that it is centered over

the plug connection and completely

enclose the plug connection

– danger of short-circuiting.

The plug connection is completely

plugged together when it has a total

length of a = max. 30 mm.

5902RA299 TG

1.2 Safety precautions

Specific national safety regulations

and the safety instructions in the

instruction manual must be

observed if the machine has to be

started up during maintenance or

repair work.

Gasoline is highly inflammable and

can also be explosive under certain

conditions.

Do not bring any fire, flame, spark or

other source of heat near the fuel.

All work with fuel must be performed

outdoors only. Spilled fuel must be

wiped away immediately.

Test for leakage after all work on the

fuel system and engine.

Exercise extreme caution while

carrying out maintenance and repair

work on the ignition system. The

high voltages which occur can

cause serious or fatal accidents.

Suitable gloves must be worn

without fail if parts are heated for

assembly/disassembly purposes.

Improper handling may result in

burns and other serious injuries.

Always replace damaged parts.

Check dismantled parts for wear

and damage before installation,

replace if necessary.

Only use the machine with the

shroud mounted – otherwise the

rotating fan wheel poses a risk of

injury and there is a risk of engine

damage due to overheating.

The chapter "Tightening Torques"

lists all components of this machine

that must be tightened with the

specified tightening torques or

coated with thread-locking

adhesive. These specifications

must be observed throughout the

Service Manual when tightening

screws and nuts as well as other

fasteners.

Fuel system – barbed connectors

Pull or push the fuel hoses, by hand

whenever possible, in the direction

of the connector in order to ensure

leakproofness of the fuel system.

Avoid damaging the barbed

connectors

– sharp-edged pliers, screwdrivers,

etc., may not be used.

Also, do not cut open fuel hoses

with a knife or similar aids.

Do not reuse fuel hoses after

disassembly, but instead always

replace them with new hoses

– fuel hoses can be overstretched

when being detached.

Mount new fuel hoses dry or using

STIHL press fluid, b 16.

Other press fluids are not permitted

and may lead to fuel hose damage.

When using STIHL press fluid,

apply press fluid to the ends of the

hose and the connectors and press

the new hoses onto the barbed

connectors, b 16.

5MS 241 C

2. Specifications

2.1 Engine

MS 241 C

Displacement: 42.6 cm

Bore: 42.5 mm

Stroke: 30.0 mm

Engine power to ISO 7293: 2.2 kW (3.0 HP)

at 10000 rpm

Max. permissible engine speed

(with bar and chain): 14000 rpm

Idle speed: 2800 rpm

Clutch: Centrifugal clutch without

linings

Clutch engages at: 3500 rpm

Crankcase leakage test

at gauge pressure: p

= 0.5 bar

under vacuum p

= 0.5 bar

2.2 Fuel system

Carburetor leakage test at

gauge pressure: p

= 0.8 bar

Operation of tank vent at

gauge pressure: p

= 0.5 bar

Fuel: as specified in instruction

manual

2.3 Ignition system

Air gap between control unit

and fanwheel: 0.30 (+ 0.05/- 0.10) mm

Spark plug (suppressed): NGK CMR 6 H

Electrode gap: 0.5 mm

2.4 Chain lubrication

Speed-controlled oil pump with reciprocating piston and

manual oil flow control

Oil flow settings:

min:

max:

4.0 (+/- 2.0) cm

/min

at 7000 rpm

8.0 (+/- 3.0) cm

/min

at 7000 rpm

6 MS 241 C

2.5 Tightening torques

DG and P screws are fitted in plastic and light alloy metal parts. These screws form a permanent thread when

they are installed for the first time. The material is permanently deformed. Screws can be removed and installed

as often as necessary without impairing the strength of the screwed assembly, provided that the specified

tightening torque is observed.

For this reason it is essential to use a torque wrench.

Fastener Thread size For component Tightening

torque

Comment

Screw P 4x12 Cover plate / fan housing 2.0

Screw P 4x10 Cover / tank housing 1.0

Screw D 4x12 Cover / chain tensioner / crankcase 2.5 2), 4)

Screw M 5x16 Antivibration element / crankcase 8.0 2), 4)

Screw P 5x34 Antivibration element / tank housing 4.0

Screw D 4x12 Brake band / crankcase 3.0 2), 4)

Screw P 4x10 Brake cable support / tank housing 1.0 Q

Stud M 5x18 Stud 7.0 2), 3)

Stud M 8 Bar mounting stud 23.0 1)

Stud M 8 Bar mounting stud 23.0 1), B

Stud D 8x18 Bar mounting stud (repair solution) 16.0

Screw D 4x12 Cover, chain brake / crankcase 3.0 2), 4)

M 10x1 Decompression valve 14.0

Nut M 5 Filter base / baffle / carburetor 3.5

Screw M 4x12 Generator / crankcase 3.0 3), VW

Screw P 6x25 Handlebar / locking screw 8.0 VW

Screw P 6x26.5 Handlebar / tank housing right 6.0

Screw P 6x30 Handlebar / tank housing right 6.0 2), 4), VW

Screw M 5x16 Handlebar / tank housing bottom 5.0 2), 3)

Screw M 5x12 Handlebar / tank housing bottom 8.0 3), VW

Screw M 5x16 Handlebar / plugs antivibration springs 10.0 2), 3), VW

Screw M 5x20 Hand guard / fan housing / crankcase 6.0 3)

Screw P 6x30 Chain catcher / crankcase / bearing plugs 6.0

Nut M 5 Spiked bumper / crankcase / upper lock nut 8.0

Screw M 5x10 Spiked bumper / top of crankcase 8.0 2), 3)

Screw M 5x16 Spiked bumper / bottom of crankcase 8.0 2), 3)

Screw D 4x12 Manifold / cylinder 4.0 2), 4)

Screw M 5x20 Crankcase drive side / fan side 10.0 2), 4)

Screw M 5x16 Bearing plugs / cylinder 10.0 2), 3)

Screw M 5x16 Fan housing / crankcase 6.0 2), 4)

Screw D 4x12 Air guide shroud / crankcase 4.0 2), 4)

7MS 241 C

Fastener Thread size For component Tightening

torque

Comment

Carrier M 12x1 L Crankshaft carrier 50.0

Screw D 4x12 Oil pump / crankcase 4.0 2), 4)

Screw M 5x16 Muffler / crankcase 10.0 2), 3)

Screw M 5x16 Muffler / cylinder 10.0 2), 3)

Nut M 8x1 Flywheel / crankshaft 28.0 5)

Nut M 12x0.75 Switch 2.0

Screw P 4x10 Support 1.0

Screw D 4x12 Pre-separator / crankcase 4.0 2), 4)

M 10x1 Spark plug / cylinder 12.0

Screw D 4x20 Control unit / cylinder 4.5 2), 4)

Screw M 5x20 Cylinder / crankcase 1st stage 4.0 2), 4)

Screw M 5x20 Cylinder / crankcase 2nd stage 10.0 2), 4)

Remarks:

1) Loctite 242 or 243 medium strength

2) Screws with locking serration

3) Microencapsulated screws

4) Screws with easy-slide coating

5) Connection between crankshaft and flywheel must be degreased and oil-free

Q) QuickStop Super

B) Quick chain tensioner

VW) Heating

When inserting DG and P screws into an existing screw thread:

Insert the DG or P screw in the hole and turn counterclockwise until it gently drops into the hole in axial direction.

Tighten the screw clockwise to the specified torque.

This procedure ensures that the screw engages properly in the existing thread and does not form a new thread

and weaken the assembly.

Coat micro-encapsulated screws with Loctite 242 or 243 medium strength before refitting them.

Screwdriver speed when used in plastic material: max. 500 rpm for DG and P-type screws.

Do not use an impact wrench to release or tighten screw connections.

Screws with and without locking serration must not be confused.

8 MS 241 C

3. Troubleshooting

3.1 Clutch

Problem Cause Remedy

Saw chain becomes stuck under

full load

Clutch shoes badly worn Install new clutch

Clutch drum badly worn Install new clutch drum

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Tension springs of the clutch shoes

are stretched

Replace tension springs, replace

clutch if necessary

Tension springs of the clutch shoes

are broken

Replace tension springs

Loud noises Tension springs stretched Replace all tension springs

Needle cage damaged Replace needle cage

Clutch shoe retainer broken Examine retainer, replace if

necessary

Clutch shoes and carrier worn Install new clutch

9MS 241 C

3.2 Chain Drive, Chain Brake, Chain Tensioner

Problem Cause Remedy

Chain sprocket wears rapidly Chain not properly tensioned Tension chain as specified

Wrong chain pitch Fit chain of correct pitch

Insufficient chain lubrication Check chain lubrication

Saw chain becomes stuck under

full load

Clutch shoes badly worn Install new clutch

Clutch drum badly worn Install new clutch drum

Brake band stuck Check freedom of movement and

function of brake band

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Tension springs of the clutch shoes

are stretched

Replace tension springs, replace

clutch if necessary

Tension springs of the clutch shoes

are broken

Replace tension springs

Saw chain does not stop

immediately when brake is

activated

Brake spring stretched or broken Fit new brake spring

Brake band stretched, worn or

broken

Fit new brake band

Clutch drum worn Install new clutch drum

10 MS 241 C

Problem Cause Remedy

QuickStop Super

Coasting brake is not released

although trigger interlock is pressed

Brake cable stretched Adjust brake cable

Brake cable unhooked or broken Reattach or replace brake cable

QuickStop Super

Brake band is not released

although trigger interlock is pressed

Excessive play on trigger interlock Adjust brake cable

QuickStop Super

Coasting brake does not brake

properly – trigger interlock not

pressed

Brake cable overstretched Adjust brake cable

Sleeve of the brake cable not

seated completely in adjusting

screw

Push the sleeve into the adjusting

screw as far as it will go and adjust

brake cable

11MS 241 C

3.3 Chain lubrication

In the event of trouble with the

chain lubrication system, check and

rectify other sources of faults

before disassembling the oil pump.

Problem Cause Remedy

Chain receives no oil Oil inlet hole in guide bar is blocked Clean oil inlet hole

Intake hose or pick-up body

clogged or intake hose ruptured

Fit new intake hose and pick-up

body

Valve in oil tank blocked Clean or replace valve

Worm worn Replace worm

Oil pump damaged or worn Install new oil pump

Machine looses chain oil Oil pump damaged or worn Install new oil pump

Oil intake hose connection

damaged

Fit new oil intake hose

Crankcase cracked Check crankcase halves and

replace damaged crankcase halves

Oil pump delivers insufficient oil Oil pump damaged or worn Install new oil pump

Worm carrier is loose Replace worm

12 MS 241 C

3.4 Starter

Problem Cause Remedy

Starter rope broken Rope pulled out too vigorously as

far as stop or over edge, i.e. not

vertically

Replace starter rope

Normal wear Replace starter rope

Starter rope does not rewind Heavy fouling or rust on rewind

spring

Clean or replace rewind spring

Spring insufficiently tensioned Check rewind spring and increase

tension

Rewind spring broken Replace rewind spring

Starter rope cannot be pulled out

far enough

Rewind spring overtensioned Check rewind spring and reduce

tension

Starter rope can be pulled out

almost without

resistance (crankshaft does not

turn)

Guide peg on pawls or pawls

themselves are worn

Replace pawls

Spring clip fatigued Replace spring clip

Spring clip improperly installed Install spring clip properly

...Versions with ErgoStart Guide peg on pawls or pawls

themselves are worn

Replace pawls

Torsion spring on flywheel are

fatigued, pawls are worn or sticking

Clean mounts on the pawls,

replace pawls and torsion springs if

necessary

Lugs on carrier are worn Replace carrier

Anchor loop in spring housing not

hooked onto carrier

Hook anchor loop to carrier

Starter rope is difficult to pull –

versions with ErgoStart

Spring in spring housing is fatigued Replace spring housing

13MS 241 C

Problem Cause Remedy

Starter rope is difficult to pull or

rewinds very slowly

Starter mechanism is very dirty Thoroughly clean complete starter

mechanism

At very low outside temperatures:

Lubricant oil on the rewind spring

becomes viscous (spring winding

stick together) or moisture has

penetrated the rewind spring

(spring windings are frozen)

Coat rewind spring with a little

standard solvent-based degreasant

(containing no chlorinated or

halogenated hydrocarbons), then

pull rope carefully several times

until normal action is restored

14 MS 241 C

3.5 Ignition system

Problem Cause Remedy

Engine runs roughly, misfires,

temporary loss of power

Spark plug boot is loose Press boot firmly onto spark plug

and fit new spring if necessary

Spark plug sooted, smeared with oil Clean the spark plug or replace if

necessary

In the event of repeated sooting,

check air filter

Fuel/oil mixture

– contains too much oil

Use a fuel mixture with the correct

mixing ratio

Wrong air gap between control unit

and flywheel

Set the correct air gap

Flywheel is cracked

or has other damage or pole shoes

have turned blue

Install new flywheel

Incorrect ignition timing, flywheel

out of adjustment

– Key in flywheel has sheared off

Install new flywheel

Weak magnetization in flywheel Install new flywheel

Irregular spark Check operation of switch shaft/

contact spring and control unit

Damaged insulation or interruption

in ignition lead or short circuit wire.

Check ignition lead/control unit,

replace control unit if necessary.

Check operation of spark plug,

clean spark plug and replace if

necessary. Check M-Tronic

15MS 241 C

3.6 Carburetor

Problem Cause Remedy

Carburetor floods; engine stalls Inlet needle not sealing

– Foreign matter in valve seat or

cone

Remove and clean inlet needle or

clean carburetor

Inlet needle worn Replace inlet needle

Inlet control lever sticking on

spindle

Examine control lever, replace if

necessary

Helical spring not located on nipple

of inlet control lever

Remove the inlet control lever and

refit it correctly

Perforated disc on diaphragm is

deformed and presses constantly

against the inlet control lever

Replace metering diaphragm

Metering diaphragm is deformed Replace metering diaphragm

Poor acceleration Carburetor setting too lean Check M-Tronic

Carburetor setting too rich Check M-Tronic

Inlet needle sticking to valve seat Remove inlet needle, clean and

refit

Diaphragm gasket leaking Replace diaphragm gasket

Metering diaphragm damaged or

shrunk

Replace metering diaphragm

Tank vent faulty Replace tank vent

Leak in fuel line between tank and

carburetor

Seal connections or replace line

16 MS 241 C

Problem Cause Remedy

Engine will not idle, idle speed too

high

Throttle shutter is not closed

properly when the throttle trigger is

not pressed

Examine carburetor and throttle

rod, replace if necessary

Oil seals or crankcase leaking Seal oil seals or crankcase, replace

if necessary

Throttle shutter does not close Replace carburetor

Engine stops when idling Idle jet bores

or ports blocked

Clean the carburetor

Idle jet too rich or

too lean

Check M-Tronic

Tank vent faulty Replace tank vent

Leak in fuel line between tank and

carburetor

Seal connections or replace line

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Clutch springs stretched or fatigued Replace tension springs, replace

clutch if necessary

Anchor loops of the clutch spring

hooks are broken

Replace tension springs

17MS 241 C

Problem Cause Remedy

Engine speed drops quickly under

load – low power

Air filter dirty Clean air filter, replace if necessary

Throttle shutter not opened fully Check throttle rod

Tank vent faulty Replace tank vent

Fuel pick-up body dirty Replace pickup body

Fuel strainer dirty Clean fuel strainer in carburetor,

replace if necessary

Leak in fuel line between tank and

carburetor

Seal connections or replace line

Carburetor setting too lean Check M-Tronic

Main jet bores or ports blocked Clean the carburetor

Pump diaphragm damaged or

fatigued

Replace pump diaphragm

Incorrect ignition timing, flywheel

out of adjustment

– Key in flywheel has sheared off

Install new flywheel

Engine runs extremely rich, lacks

power and has very low final speed

Choke shutter does not open Examine the carburetor and starter

shaft and repair or replace if

necessary

Carburetor setting too rich Check M-Tronic

18 MS 241 C

3.7 Engine

Always check and, if necessary,

repair the following parts before

looking for faults on the engine:

- Air filter,

- Fuel system,

- Carburetor,

- Ignition system

Problem Cause Remedy

Engine does not start easily, stalls

at idle speed but operates normally

at full throttle

Oil seals in engine defective Replace oil seals

Crankcase leaking or

damaged (cracks)

Replace damaged crankcase

halves

Intake manifold damaged/ hole is

plugged

Clean hole or replace intake

manifold

Engine does not deliver full power

or runs erratically

Piston rings worn or broken Replace piston rings

Muffler / spark arresting screen

carbonized

Clean muffler (inlet and outlet

openings), replace spark arresting

screen, replace muffler if necessary

Air filter dirty Clean or replace air filter

Fuel line kinked or cracked Replace fuel line and ensure that is

installed without kinking

Intake manifold damaged / hole is

plugged

Clean hole or replace intake

manifold

Engine is overheated Insufficient cylinder cooling. Air

inlets in fan housing blocked or

cooling fins on cylinder very dirty

Thoroughly clean all cooling air

openings and the cylinder fins

Air intake in fan housing is fouled Clean air intake on fan housing

19MS 241 C

4. Clutch

4.1 Clutch drum

– Clutch drum removal and

installation, see Instruction

Manual

– Remove needle cage

– Clean needle cage and

crankshaft stub, b 16

– Grease needle cage and

crankshaft stub, b 16

– Examine the clutch drum (1) for

signs of wear

The remaining thickness must be

measured if there are distinct signs

of wear on the inside diameter of the

clutch drum (1). The clutch drum

must be replaced if the remaining

thickness is less than approx. 80 %

of the original thickness.

– Install the clutch drum

4.2 Clutch

– Troubleshooting, b 3.1

– Removing the clutch drum,

b 4.1

– Remove shroud, b 6.4

80%

100%

5902RA018 TG

: Remove the spark plug boot (1)

– Unscrew spark plug

: Orient the locking strip (1)

0000 893 5904 so that the flat

side of the metallic attachment

faces the piston and insert it in

the cylinder

: Locking strip (1) 0000 893 5904

must rest against the cylinder

wall (arrow) and the flat side of

the metal attachment must rest

against the piston head

– Position as shown

2410RA001 TG

2410RA002 TG

2410RA003 TG

: Unscrew the clutch (1) with

hexagon (arrow) – left-hand

thread

Installation

Slide washer (1) into place so that

the word "TOP" is visible.

: Fit the clutch (2) on the

crankshaft stub so that the raised

hexagon (arrow) can be seen

: Screw on and tighten the

clutch (2) – left-handed thread

– Pull the locking strip out of the

cylinder

– Reassemble remaining parts in

reverse order

2410RA004 TG

TOP

2410RA005 TG

20 MS 241 C

5. Chain brake

5.1 Checking operation of

chain brake

The chain brake is one of the most

important safety devices on the

chain saw. Its efficiency is

measured in terms of the chain

braking time, i.e., the time that

elapses between activating the

brake and the saw chain coming to

a complete standstill.

Fouling (particularly with chain oil,

chips, fine particles of abrasion,

etc.) and smoothing of the friction

surfaces of the brake band and

clutch drum impair the coefficient of

friction. This in turn extends the

braking time. A fatigued or stretched

brake spring has the same negative

effect.

– Starting the engine

– With the chain brake

activated (locked), open the

throttle wide for a brief

period (max. 3 seconds) – the

chain must not rotate

– With the chain brake released,

open the throttle wide and

activate the brake manually – the

chain must come to an abrupt

stop

Versions with QuickStop Super

When the trigger interlock is

pressed, the clutch drum must

rotate freely.

With the coasting brake released,

open the throttle wide and release

the trigger interlock in the rear

handle – the saw chain must come

to an abrupt stop

All versions

The braking time is in order if

deceleration of the saw chain is

imperceptible to the eye (less than 1

second).

If the chain brake does not operate

properly, refer to the

troubleshooting chart, b 3.2.

5.2 Brake band

– Remove the clutch drum, b 4.1

– Troubleshooting, b 3.2

: Remove screws (1)

: Remove the cover (2)

– Block chain brake

: Unscrew screw (1) on the bottom

of the machine

2410RA006 TG

2410RA007 TG

: Ease brake band (2) out of

guide (arrow)

– Remove brake band, taking care

not to overextend it

– Release the chain brake

: Turn brake band (1) slightly aside

and disconnect it from the brake

lever (2)

Install a new brake band if there are

noticeable signs of wear on large

areas on the inside diameter and/or

parts of the outside (arrows) and its

remaining thickness is less than

< 0.6 mm.

5902RA024 TG

219RA049 TG

21MS 241 C

Installation

– Release the chain brake

: Attach brake band (1) to brake

lever (2) sideways and turn it

towards its mount

: Insert brake cable (1) in

guide (arrow)

– Block chain brake

: Guide brake band (1) over

studs (arrows) and press it into

the mount

2410RA009 TG

2410RA010 TG

2410RA011 TG

: Push brake band (1) fully home in

the mount (arrow)

: Screw in and tighten screw (2) on

the bottom of the machine

: Insert cover (1)

: Insert and tighten down the

screws (2)

– Install the clutch drum, b 4.1

When the chain brake is released,

the clutch drum must rotate freely.

– Carry out additional function

tests, b 5.1

– Reassemble remaining parts in

reverse order

2410RA012 TG

2410RA013 TG

5.3 Brake lever

– Troubleshooting, b 3.2

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove brake band, b 5.2

– Block chain brake

The brake spring is now relaxed.

: Use the assembly tool

1117 890 0900 to unhook the

brake spring (1) at the anchor

pin (arrow)

– Unhook and remove the brake

spring at the brake lever

2410RA014 TG

22 MS 241 C

: Push out circlip (1)

: Draw hand guard (1) and brake

lever (2) off the anchor

pins (arrows) simultaneously

– Take out hand guard and brake

lever

– Examine cam lever and replace if

necessary, b 5.5

: Pull brake lever (2) out of hand

guard (1)

2410RA015 TG

2410RA016 TG

2410RA017 TG

– Examine pins and replace if

necessary, b 5.6

– Check cam on hand guard,

replace hand guard if necessary

Installation

– Clean pins and disassembled

parts, b 16

– Grease pins, b 16

: Position brake lever (2) so that

mount for brake spring (arrow) is

at the top

: Slide brake lever (2) into recess

in hand guard (1) until the holes

are lined up

: Slide hand guard (1) with brake

lever (2) across the machine until

it rests against the anchor

pins (arrows)

2410RA018 TG

2410RA019 TG

: Slightly lift up bearing eye of the

hand guard (1) and brake

lever (2) and guide the parts over

the anchor pins (arrows)

: Turn cam lever (1) slightly aside

until cam of hand guard (arrow)

slides past

– Press bearing eye of hand guard

and brake lever onto the anchor

pins

: Push circlip (1) into place

2410RA020 TG

2410RA021 TG

2410RA022 TG

23MS 241 C

The turns of the brake spring must

be tightly spaced when not installed;

use a new brake spring if necessary.

– Position the protective tube so

that it starts after the

second turn (arrow)

– The pin for the brake spring must

be replaced if it shows signs of

wear at the groove, b 5.6

: Hook brake spring (1) into brake

lever (arrow)

5902RA040 TG2410RA023 TG

: Use the assembly tool (2)

1117 890 0900 to attach the

brake spring (1) to the anchor

pin (arrow)

– Grease brake lever, cam lever

and hand guard motion link,

b 16

– Reassemble remaining parts in

reverse order

5.4 QuickStop Super brake

lever

– Troubleshooting, b 3.2

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove brake band, b 5.2

– Block chain brake

The brake spring is now relaxed.

: Use the assembly tool

1117 890 0900 to unhook the

brake spring (1) at the anchor

pin (arrow)

2410RA024 TG

2410RA025 TG

– Unhook and remove the brake

spring at the brake lever

: Unhook brake spring (1) from

anchor pin (arrow)

: Unhook and remove the brake

spring (1) at the brake lever

: Draw hand guard (1) and brake

lever (2) off the anchor

pins (arrows) simultaneously

– Take out hand guard and brake

lever

2410RA026 TG

2410RA027 TG

24 MS 241 C

: Disconnect brake cable (1)

: Pull brake lever (2) out of hand

guard (1)

– Examine cam lever and replace if

necessary, b 5.5

– Examine pins and replace if

necessary, b 5.6

– Check cam on hand guard,

replace hand guard if necessary

2410RA028 TG

2410RA029 TG

Installation

– Clean pins and disassembled

parts, b 16

– Grease pins, b 16

: Position brake lever (2) so that

mount for brake spring (arrow) is

at the top

: Slide brake lever (2) into recess

in hand guard (1) until the holes

are lined up

: Attach brake cable (1) to

hole (arrow) in brake lever

2410RA030 TG

2410RA031 TG

: Slide hand guard (1) with brake

lever (2) across the machine until

it rests against the anchor

pins (arrows)

: Slightly lift up bearing eye of the

hand guard (1) and brake

lever (2)and guide the parts over

the anchor pins (arrows)

2410RA032 TG

2410RA033 TG

25MS 241 C

: Turn cam lever (1) aside until

cam of hand guard (arrow) slides

past

– Press bearing eye of hand guard

and brake lever onto the anchor

pins

: Check seat of the sleeve (1) at

the brake cable, push completely

into the hole in the

housing (arrow) if necessary

: Hook brake spring (1) into the

brake lever so that the opening of

the anchor loop (arrow) is visible

2410RA034 TG2410RA035 TG

2410RA036 TG

: Attach brake spring (1) to anchor

pin (2)

The turns of the brake spring must

be tightly spaced when not installed;

use a new brake spring if necessary.

– Position the protective tube so

that it starts after the

second turn (arrow)

– The pin for the brake spring must

be replaced if it shows signs of

wear at the groove, b 5.6

: Hook brake spring (1) onto brake

lever (arrow)

5902RA040 TG

2410RA037 TG

: Use the assembly tool

1117 890 0900 to hook the brake

spring (1) onto the anchor

pin (arrow)

– Grease brake lever, cam lever

and hand guard motion link,

b 16

– Adjust brake cable, b 5.4.1

– Reassemble remaining parts in

reverse order

5.4.1 Adjusting brake cable

If the coasting brake does not

operate properly although the brake

band is intact, it may be necessary

to adjust the brake cable.

– Troubleshooting, b 3.2

– Check condition and play

– Remove chain brake cover,

b 5.2

When the trigger interlock is not

pressed, the brake cable must

be without tension.

2410RA025 TG

26 MS 241 C

– Press and hold the trigger

interlock down completely

Brake band (1) must rest against

the crankcase (arrows) without play

and the clutch drum must rotate

freely.

– Release trigger interlock

: Press trigger interlock (1) gently

to check the play

– The play must not exceed the

mark (a)

Play: is equal to the distance

traveled by the trigger interlock (1)

without causing the brake lever to

move at the same time.

Play is necessary to ensure trouble

free functioning of the coasting

brake.

– Troubleshooting, b 3.2

2410RA038 TG

0001RA456 TG

Adjust brake cable

: Remove screw (1)

: Lower tank housing (2)

: Loosen clamping screw (1) on

the support for the brake cable

The sleeve (1) must be seated on

the adjusting screw (2) as far as it

will go.

: Position open-end wrench SW 6

on the adjusting screw (2) and

adjust play

2410RA039 TG

2310RA050 TG

2410RA556 TG

: Screw in adjusting screw (2)

– Play increases

: Unscrew adjusting screw (2)

– Play decreases

: Once play is adjusted correctly,

tighten clamping screw (3)

– Press and hold the trigger

interlock down completely

Brake band (1) must rest against

the crankcase (arrows) without play

and the clutch drum must rotate

freely.

– Reassemble remaining parts in

reverse order

2410RA038 TG

27MS 241 C

5.4.2 Brake cable

Removal and installation

– Unhook brake spring, b 5.4

– Remove QuickStop Super

throttle trigger, b 11.3

– Remove QuickStop Super trigger

switch, b 11.3.1

: Pull brake cable (1) out slightly

and disconnect it

– Loosen tank housing and lower it,

b 13.11.2

– Do not overextend fuel hose

: Remove screw (1)

: Remove support (2) with brake

cable

2410RA040 TG

2410RA041 TG

: Examine brake cable (1) and

support (2), replace if necessary

Dismantle brake cable and

support

: Unscrew clamping screw (1) and

adjusting screw (2)

: Turn hook (3) so that the angled

part is at the opening (arrow) and

twist it out of the support (4)

Installation

: Turn hook (1) so that it runs along

the support (2) and push it into

the hole (arrow)

2310RA053 TG

2310RA054 TG

3 4

2310RA055 TG

: Push hook (1) through the

support (2) with a gentle twisting

motion

: Turn adjusting screw (1) until the

distance between the hexagon of

the adjusting screw and the

holder is 2 mm

: Screw in the clamping screw (2)

and tighten

: Guide the brake cable (1) over

fuel hose (3) or, in versions with

manual fuel pump, over the fuel

hose (3) and fuel return line (2)

: Push brake cable (1) with short

hook (4) in front through the

hole (arrow) in the crankcase

2310RA056 TG

2410RA042 TG

28 MS 241 C

: Push brake cable (1) with sleeve

into the hole in the

housing (arrow) as far as it will go

: Hook brake cable (1) into

hole (arrow) in brake lever (2)

: Press brake cable holder with the

pin (1) through the opening and

into the mount (arrow)

: Screw in the screw (2) and

tighten it

2410RA043 TG

2410RA044 TG

1 2

2410RA045 TG

When raising the tank housing,

make certain that the sleeve (1) is

pushed completely into the

adjusting screw (2) – incomplete

insertion of the sleeve changes the

setting of the brake cable.

– Check position of the fuel hose

and correct it if necessary,

b 13.11.2

– Check position of the fuel return

line and correct it if necessary,

b 13.11.3

– Raise and fasten the

tank housing, b 13.11.2

: Insert brake cable (1) in

guide (arrow)

– Install QuickStop Super trigger

switch, b 11.3.1

– Install QuickStop Super throttle

trigger, b 11.3

2410RA046 TG

2410RA047 TG

– Reassemble remaining parts in

reverse order

– Adjust brake cable and check

operation, b 5.4.1

5.5 Cam lever

The cam lever defines the engaged

position of the hand guard.

– Remove brake lever, b 5.3,

QuickStop Super, b 5.4

: Unhook the brake spring (1) from

the anchor pin (2)

– Unhook and remove the brake

spring (1) at the cam lever

: Push out circlip (3)

– Remove cam lever

2410RA048 TG

29MS 241 C

: Examine cam lever (1) and brake

spring (2) and replace if

necessary

: Check condition of cam

guide (arrow) and replace hand

guard if necessary

– Examine all pins and replace if

necessary,

b 5.6

Installation

– Clean pins and disassembled

parts, b 16

– Grease pins, b 16

: Orient cam lever (1) so that the

cam (arrow) faces the pin (3)

: Slide cam lever (1) onto anchor

pin (2)

2410RA049 TG

2410RA050 TG

: Push circlip (1) into place

: Hook brake spring (1) into the

brake lever so that the opening of

the anchor loop (arrow) is visible

: Hook brake spring (1) onto

pin (2)

– Grease cam lever, b 16

The cam lever is not yet tensioned –

the spring may become detached

again.

– Reassemble remaining parts in

reverse order

2410RA051 TG

2410RA052 TG

5.6 Pins

The pins ensure that the springs are

securely mounted. They must

therefore be replaced when worn,

otherwise the springs may pop out.

The pins must be driven in square.

For reasons of simplicity, the parts

connected to the pins have already

been removed in the following

illustrations.

: Remove pins (1) through (6)

Item 6 is present only in the version

with QuickStop Super.

2410RA053 TG

132

30 MS 241 C

Installation

– Coat the knurled area of the new

pin with Loctite before fitting the

pin, b 16

: The pin must be inserted in the

hole (arrow) so that the knurling

on the pin engages the knurled

profile

Turn the pin back and forth slightly

until it fits.

The pins must be driven in square.

: Drive in pins (1) and (2) in

accordance with the following

information

2410RA054 TG2410RA055 TG

: Pin (1) a = approx. 2.9...3.3 mm

Pin (2) b = approx. 4.3...4.7 mm

: Drive in anchor pins (3), (4)

and (5) in accordance with the

following information

: Pin (3) a = approx. 8.9...9.1 mm

Pin (4) b = approx. 4.6...4.8 mm

Pin (5) c = approx. 5.1...5.3 mm

0001RA061 TG

2410RA056 TG

4 5

2410RA057 TG

Machines with QuickStop Super

: Drive in anchor pins (5) and (6) in

accordance with the following

information

: Pin (5) b = approx. 5.1...5.3 mm

Pin (6) a = approx. 2.9...3.3 mm

– Reassemble remaining parts in

reverse order

– Grease brake and cam levers,

b 16

2410RA058 TG

2410RA059 TG

31MS 241 C

5.7 Chain tensioner

– Troubleshooting, b 3.2

: Turn the spur gear (2) clockwise

until the tensioner slide (1)

makes contact on the right and

the screw (3) is revealed

: Remove screw (3)

: Remove spur gear (2) and

tensioner slide (1)

: Examine the cover (1), spur gear

kit (2), tensioner slide (3) and

thrust pad (4) and replace if

necessary

– Clean all disassembled parts,

b 16

– Coat the threads and gear

wheels with STIHL multi-purpose

grease, b 16

– Reassemble parts in reverse

order

2410RA060 TG

1 3

2410RA061 TG

5.7.1 Quick chain

tensioner

The quick chain tensioner is built

into the chain sprocket cover.

: Unscrew screw (1) and remove

side plate (2), remove Loctite

residue if necessary

– Examine side plate, replace if

necessary

– Coat screw with Loctite before

insertion, b 16

– Install parts in reverse order

: Carefully pry out wing nut (1) at

the side (arrow)

– Check wing nut (1) and replace if

necessary

2410RA544 TG

2410RA062 TG

– Fold out wing nut (1)

: Push wing nut (1) into the

opening thin side (arrow) first,

then press it in until it snaps into

place

: Remove the screw (arrow)

: Remove cover plate (1) and

adjusting wheel (2)

When installing the adjusting wheel,

make certain that the teeth face the

cover plate

– Reassemble the parts in reverse

order

2410RA063 TG

2410RA064 TG

32 MS 241 C

5.7.2 Chain catcher

– Remove the chain sprocket cover

: Remove screw (1) and pull out

chain catcher (2) under the

bumper strip

– Reassemble parts in reverse

order

5.8 Bar mounting stud

– Remove the chain sprocket cover

: Push stud driver (1)

5910 893 0501 onto the stud (2)

as far as it will go and unscrew

counterclockwise

– Coat stud with Loctite, screw in

and tighten, b 16

2410RA300 TG

2410RA065 TG

– Reassemble remaining parts in

reverse order

5.9 Collar nut for chain

sprocket cover

This chain sprocket cover can only

be used on the MS 241.

It cannot be retrofitted to other

models. The length and shape of

the stud must be appropriate for the

chain sprocket cover with captive

nut.

The special tool stud

5910 893 9600 is available for

replacing the nut.

– Remove the chain sprocket cover

: Screw the assembly tool (1)

5910 893 9600 with the short

stud into the collar nut (2) as far

as it will go

2410RA066 TG

– Flip over the chain sprocket cover

and clamp the assembly tool into

a vise by the hexagon

: Drill out the collar nut with an

11 mm diameter drill bit – the

base in the chain sprocket cover

must not be drilled out

– Pull out the collar nut

– Unscrew the assembly tool from

the collar nut

2410RA067 TG

33MS 241 C

Installation

: Push in new collar nut (1)

– Hold the hexagon of the collar nut

in place

: Screw the assembly tool (1)

5910 893 9600 with the long stud

into the opposite side of the collar

nut as far as it will go

Now the new collar nut has been

flanged and secured in the chain

sprocket cover.

– Reassemble remaining parts in

reverse order

2410RA068 TG

2410RA069 TG

34 MS 241 C

6. Engine

6.1 Muffler

Check and if necessary repair the

fuel supply, carburetor, air filter and

ignition system before looking for

faults on the engine.

– Troubleshooting, b 3.7

– Remove shroud, b 6.4

To keep dirt particles from entering

the cylinder, move piston to top

dead center before removing the

muffler.

: Pry out the stoppers (1) around

the circumference at the

markings

– Do not reuse dismantled

stoppers

: Remove screws (1) and (2)

: Take out and examine the

muffler (3), replace if necessary

– Remove exhaust gasket

– always use a new exhaust

gasket

2410RA070 TG

1 1

2410RA071 TG

2 2

– Remove and install spark

arresting screen, if present, see

Instruction Manual

Installation

– Cover exhaust bore and remove

any fouling on the cylinder and

exhaust bore

: Examine and clean the mating

surfaces (arrows), remove any

gasket residues if necessary –

there must not be any gasket

residues or dirt particles in the

exhaust bore

Parts with damaged mating

surfaces must be replaced.

: Orient the exhaust gasket (1) so

that the tabs (arrows) face

towards the cylinder

: Fit the exhaust gasket (1) and

orient it with the tabs (arrows) on

the connector of the cylinder

2410RA072 TG2410RA073 TG

: Carefully fit the muffler (1)

: Fit screws (2) and check that

gasket is correctly positioned

: Insert screws (3) – do not tighten

: First tighten screws (2), then

tighten screws (3)

– Press in new stoppers evenly and

straight around the

circumference with a blunt tool –

do not insert them on a slant or

damage them

2410RA071 TG

3 3

35MS 241 C

6.2 Leak testing

Defective oil seals and gaskets or

cracks in housing are the usual

causes of leaks. Such faults allow

supplementary air to enter the

engine and upset the fuel-air

mixture.

This makes adjustment of the

prescribed idle speed difficult, if not

impossible.

Moreover, the transition from idle

speed to part or full throttle is not

smooth.

Always start with the vacuum test

and then continue with the pressure

test.

The engine can be thoroughly

checked for leaks under vacuum

and at gauge pressure using the

pump 0000 850 1300.

6.2.1 Preparations

– Remove shroud, b 6.4

– Take off the spark plug boot and

remove the spark plug

– Set the piston to the top

dead center (this can be checked

through the spark plug hole)

– Remove the decompression

valve, b 6.9

: Fit the stopper (1) 1122 025 2200

and screw it tight

: Screw in spark plug (2) and

tighten it securely

– Remove muffler and gasket,

b 6.1

: Position flange (1)

5910 855 4201 on cylinder

exhaust port

: Screw in screws (2)

– do not tighten

2410RA075 TG

2410RA076 TG

2 2

The flange (1) 4224 893 2501 can

be reworked as shown.

a=13 mm

b=39.25mm

c=6mm

: Slide sealing plate (1)

0000 855 8106 between cylinder

exhaust port and flange (2)

: Tighten screws (3) lightly

The sealing plate must fill the full

width between the screws.

– Carefully pull out the carburetor

over the studs and lay it aside

– Do not overextend fuel hose,

b 8.4

2710RA164 TG

2410RA077 TG

36 MS 241 C

: Washer (1) must be fitted

: Orient flange (1) 1118 850 4200

and push it onto the studs

: Fit flange (1) 1118 850 4200

: Tightly screw on nuts (2)

6.2.2 Vacuum test

Oil seals tend to fail when subjected

to a vacuum. In other words, the

sealing lip lifts away from the

crankshaft during the piston's

induction stroke because there is no

internal counterpressure.

This kind of fault can be detected by

testing with pump 0000 850 1300.

2410RA078 TG

2410RA079 TG

: Push the hose (1) of pump

0000 850 1300 onto the

connector (arrow)

: Slide ring (2) to the left

– Vacuum test

: Operate lever (3) until the

pressure gauge (4) indicates a

vacuum of 0.5 bar

If the vacuum reading remains

constant, or does not decrease by

more than 0.3 bar within 20

seconds, it may be assumed that

the oil seals are in good condition.

If the vacuum in the crankcase is

reduced further, the oil seals must

be replaced, b 6.3.

– After testing, slide the ring on the

pump back to the right to vent the

pump.

– Continue with pressure test,

b 6.2.3

6.2.3 Pressure test

The same preparatory steps are

required as for the vacuum test,

b 6.2.2.

2310RA080 TG

4 3

: Slide ring (1) to the right

– Pressure test

: Operate the lever (2) until the

pressure gauge (3) indicates a

pressure of 0.5 bar. If this

pressure remains constant for at

least 20 seconds, the engine

crankcase is airtight

– If the pressure drops, the leak

must be located and the defective

part replaced

To find the leak, coat the suspect

area with soapy water and

pressurize the crankcase. Bubbles

will appear if a leak exists.

– After testing, slide the ring on the

pump to the left to vent the pump

– disconnect the hose

– Remove flange 1118 850 4200

on intake elbow

– Refit carburetor, b 8.4

– Remove flange 5910 855 4201

and sealing plate 0000 855 8106

– Refit the muffler, b 6.1

– Press in new stoppers straight

with a blunt tool

– Do not damage stoppers

– Reassemble remaining parts in

reverse order

2410RA081 TG

3 2

37MS 241 C

6.3 Oil seals

It is not necessary to dismantle the

complete engine if only the oil seals

need to be replaced.

Pull out oil seals using puller

5910 890 4400 and

jaws (profile no. 6) 0000 893 3711.

6.3.1 Ignition side

– Remove fan housing, b 9.2

– Remove the flywheel, b 7.6

Versions with heating

– Unscrew screws, remove

generator and set it aside,

b 14.7

Avoid damage to the crankshaft

stub.

– Free the oil seal in its seat by

tapping it with a suitable tube or a

punch.

: Position puller (1) 5910 890 4400

– Clamp the puller arms

– Pull out the oil seal

2410RA082 TG

Installation

– Clean the mating surface, b 16

– Grease the sealing lips of the

new oil seal, b 16

: Fit the installing sleeve (1)

1141 893 4600

: Slide the oil seal (2) over the

installing sleeve with the sealing

lip facing the crankcase

– Remove the installing sleeve (1)

: Orient press sleeve (2)

1143 893 2400 with the

collar (arrow) facing the engine

: Use the press sleeve (2)

1143 893 2400 to install the oil

seal (1)

The seating face must be flat and

free from burrs.

2410RA083 TG

2410RA084 TG

– Clean the cone of the crankshaft

to ensure it is completely grease-

free, b 16

– Reassemble remaining parts in

reverse order

6.3.2 Clutch side

– Remove the clutch, b 4.2

– Remove oil pump, b 12.3

: Remove the circlip (1)

2410RA085 TG

38 MS 241 C

Avoid damage to the crankshaft

stub.

– Free the oil seal in its seat by

tapping it with a suitable tube or a

punch.

: Position puller (1) 5910 890 4400

– Clamp the puller arms

– Pull out the oil seal

Installation

– Clean the mating surface, b 16

– Grease the sealing lips of the

new oil seal, b 16

: Fit the installing sleeve (1)

1141 893 4600

: Slide the oil seal (2) over the

installing sleeve with the sealing

lip facing the crankcase

2410RA086 TG

2410RA087 TG

: Remove the installing sleeve (1)

: Orient press sleeve (1)

1118 893 2401 with the

collar (arrow) facing the engine

: Use the press sleeve (1)

1118 893 2401 to install the oil

seal (2)

The seating face must be flat and

free from burrs.

: Fit the circlip (1)

– Reassemble remaining parts in

reverse order

2410RA088 TG

2410RA089 TG

6.4 Shroud

: Release quick release

locks (arrows)

– Using the combination wrench,

turn 1/4 turn counterclockwise

: Remove the shroud (1)

: Push out cap (arrow) with drift (1)

2410RA090 TG

2410RA091 TG

39MS 241 C

Installation

: Push in cap (1) with drift (2)

– Reassemble remaining parts in

reverse order

6.5 Cylinder

Before removing the cylinder,

decide whether or not the

crankshaft is to be removed.

With cylinder installed

The crankshaft must be prevented

from twisting by blocking the piston

through the spark plug hole in order

to remove the flywheel and clutch.

With cylinder removed

The crankshaft is blocked by

placing the piston on the wooden

assembly block in order to remove

the flywheel and clutch.

– Remove shroud, b 6.4

– Take off the spark plug boot and

remove the spark plug, b 4

– Remove fan housing, b 9.2

– Remove short circuit wire,

b 7.7.2

– Remove the control unit, b 7.3

– Remove filter base, b 13.3

2410RA092 TG

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove air guide shroud,

b 13.4, versions with manual

fuel pump b 13.4.1, versions

with heating b 13.4.2

– Remove the muffler, b 6.1

– Remove the decompression

valve, b 6.9

– not for version with ErgoStart

– Remove the front handle,

b 10.4

– not for version with heating

– Remove antivibration spring on

front handle, b 10.3.1

– not for version with heating

: Take out the screws (arrows)

2410RA093 TG

: Carefully pull off the cylinder (1)

: Remove the cylinder gasket (1)

: Examine and clean the mating

surface (arrow), b 16

The mating surface must be in

perfect condition and without any

damage whatsoever. Parts with

damaged mating surfaces must be

replaced, b 3.7.

2410RA094 TG

2410RA095 TG

2410RA096 TG

40 MS 241 C

: Examine the intake elbow (1),

replace if necessary. Engine

operation may be impaired even

by the slightest damage, b 3.7

: Remove screws (2)

: Remove intake elbow (1)

: Examine and clean the mating

surfaces (arrows), and remove

any gasket residues, b 16

– Clean mating surface on intake

elbow, b 16

The mating surfaces must be in

perfect condition and without any

damage whatsoever. A new cylinder

must be used if the mating surfaces

are damaged.

Always use a new cylinder gasket

after removing the cylinder.

2410RA097 TG

2410RA098 TG

Installation

: Position intake elbow (1)

: Insert and tighten down the

screws (2)

: Guide new cylinder gasket (1)

over the piston so that the

tab (arrow) faces the spiked

bumper

: Place wooden assembly

block (1) 1108 893 4800

between piston and crankcase

Avoid damage to the cylinder

gasket.

2410RA099 TG

2410RA100 TG

2410RA101 TG

– Coat piston, piston rings and

inside of cylinder with oil, b 16

: Fit clamping strap (1)

0000 893 2600 around piston

and piston rings

– Ensure that piston rings are

correctly positioned, b 6.8

The clamping strap (1) must be

fitted in such a way that the piston

rings do not protrude beyond the

piston sides.

: Orient cylinder (1) so that the

intake elbow (2) faces the control

handle

When fitting the cylinder over the

piston, ensure that the clamping

strap securely encloses the piston

and that none of the piston rings

protrudes

– danger of breakage.

: Slide cylinder over piston; the

clamping strap is removed at the

same time

2410RA102 TG

2410RA103 TG

41MS 241 C

: Remove clamping strap (1) and

wooden assembly block (2)

Make certain that the cylinder

gasket is oriented according to the

holes.

– Push cylinder home as far as

possible

: Fit screws (arrows) and secure

cylinder with gasket

: Tighten down the screws through

the holes (arrows) crosswise

– Reassemble remaining parts in

reverse order

2410RA104 TG

2410RA093 TG

6.6 Crankshaft

– Drain fuel tank and oil tank,

b 1.1

– Remove brake band, b 5.2

– Remove oil pump, b 12.3

– Remove oil suction hose,

b 12.2

– Remove brake lever, b 5.3

QuickStop Super, b 5.4

– Remove the front handle,

b 10.4

Version with heating, b 10.4.1

– Remove the tank housing,

b 13.11.5

– Remove the flywheel, b 7.6

– Version with handle heating

Remove generator, b 14.7

– Remove the cylinder, b 6.5

– Remove piston, b 6.7

– Remove spiked bumper

Always fit new ball bearings and oil

seals when removing the

crankshaft, b 6.6.1 and b 6.3.

Clutch side half of crankcase

: Remove the circlip (1)

The tools from the assembly tool kit

5910 007 2205 are used for

removal and installation.

: Take out the screws (arrows)

: Remove screws (1) and pull out

chain tensioner (2)

2410RA106 TG

2410RA107 TG2410RA105 TG

42 MS 241 C

: Unscrew screw (1), remove

Loctite residue from the threaded

hole if necessary

: On versions with quick chain

tensioner, remove side plate (2)

: Unscrew spindle (1) until it no

longer rests on the crankshaft

stub

: Push assembly tool (2) from kit

5910 007 2205 onto the

stud (arrow), twist on and tighten

the nut

: Turn spindle (1) clockwise until

the crankshaft stub has been

forced out of the ball bearing

The clutch-side half of the

crankcase is pulled off in this way

and the two halves of the crankcase

separated.

– Replace ball bearings and oil

seals, b 6.6.1 and b 6.3

2410RA544 TG

2410RA108 TG

Ignition side half of crankcase

: Remove the gasket (1)

The tools from the assembly tool kit

5910 007 2201 are used for

removal and installation.

– Use disk 5910 893 2103

The assembly took kit

5910 007 2201 can be expanded

with the disk 5910 893 2103.

The new assembly tool kit

5910 007 2201 contains all three

disks.

: Adjust the spindle (1) of the

assembly tool

so that the disk (2) rests against

the half of the crankcase

– Left-hand thread

2410RA109 TG

2410RA110 TG

: Align the assembly tool (1) with

the disk (2) 5910 893 2103

against the ignition-side half of

the crankcase so that the edge

number "24" (arrow) is at the

bottom

: Insert three M5 x 72 screws (3)

through the holes marked "24"

and screw them as far as

possible into the crankcase half

: Turn the spindle (1)

counterclockwise until the

crankshaft has been forced out of

the ignition-side half of the

crankcase

The crankshaft (1), connecting

rod (2) and the needle bearing

between them make up a complete

unit and must therefore always be

replaced as a unit.

– Check the two halves of the

crankcase and the grooved ball

bearing, replace if necessary,

b 6.6.1

– Before installation, clean the

crankshaft, b 16

2410RA111 TG

2410RRA112 TG

43MS 241 C

Installation

Ignition side half of crankcase

Avoid damage to the crankshaft

stub.

Examine and clean the mating

surfaces of the ignition-side half of

the crankcase (including the

cylinder sealing surface) – the

sealing face must not display any

signs of damage, b 16.

: Orient the crankshaft with the

conical crankshaft stub (arrow)

facing the ignition-side ball

bearing

– Wear protective gloves

– risk of burns

– Heat only the inner race of the

ball bearing to approx. 150 °C

(300 °F)

: Press crankshaft stub fully home

The crankshaft must be fitted

rapidly, as the heat is transmitted to

the crankshaft stub and the inner

bearing race contracts.

2410RA113 TG

If the inner race cannot be heated,

the crankshaft can be drawn into the

crankcase with the assembly tool

5910 007 2201.

– Use disk 5910 893 2103.

: Screw the threaded sleeve (1)

5910 893 2420 onto the

completely screwed in spindle as

far as it will go

– Coat the tapered crankshaft stub

with oil.

: Align the crankshaft with the

conical crankshaft stub (arrow)

facing the ignition-side ball

bearing and push it home

5902RA135 TG

2410RA113 TG

: Fit the screw sleeve (2) over the

thread of the conical crankshaft

stub (1) and screw it on

: By turning the spindle screw (1),

position disk 5910 893 2103

against the ignition-side half of

the crankcase and orient it so that

the edge number "24" is at the

bottom

: Insert M5x72 screws (2) through

the holes marked "24"

– anti-twist device

: Turn the spindle screw (1)

clockwise

– Draw the ignition-side half of the

crankcase in as far as possible

2410RA114 TG

2410RA115 TG

44 MS 241 C

The crankshaft also turns when it is

drawn in with the installing tool. For

this reason, ensure that the rod

eye (1) always faces upwards

towards the cylinder.

– Remove the installing tool

: Screw two screws (arrows)

M5x72 into the holes on the

ignition side

– for guidance and to prevent

twisting

2410RA116 TG

2410RA117 TG

: Fit a new gasket (1) and secure it

at the guide sleeves (arrows)

– Coat the cylindrical crankshaft

stub with oil

Clutch side half of crankcase

Avoid damage to the crankshaft

stub.

Examine and clean the mating

surfaces of the clutch-side half of

the crankcase (including the

cylinder sealing surface) – the

sealing face must not display any

signs of damage, b 16.

Ensure that the guide

sleeves (arrows) line up with the

holes and that the housing gasket is

not jammed or buckled.

2410RA118 TG

2410RA119 TG

– Wear protective gloves

– risk of burns

– Heat only the inner race of the

ball bearing to approx. 150 °C

(300 °F)

– Align the crankcase half with the

cylindrical crankshaft stub and

the two screws and position it

: Push the crankcase home until it

makes contact

The crankcase must be fitted

rapidly, as the heat is transmitted to

the crankshaft stub and the inner

bearing race contracts

If it is not possible to heat the inner

race, the crankcase half is drawn in

with the assembly tool from kit

5910 007 2205.

– Coat the cylindrical crankshaft

stub with oil

– Align the crankcase half with the

cylindrical crankshaft stub and

the two screws and position it

2410RA120 TG

45MS 241 C

– By turning it, screw the spindle

completely into the assembly tool

: Screw the threaded sleeve (1)

5910 893 2409 onto the spindle

as far as it will go

– Left-hand thread

: Fit threaded sleeve on crankshaft

stub (arrow) and push assembly

tool over the studs

165RA133 TG

0001RA494 TG

: Hold crankshaft steady and

screw threaded sleeve onto

thread of crankshaft stub by

turning the spindle

counterclockwise

– Release crankshaft and hold

assembly tool steady and

continue turning the spindle until

the assembly tool rests against

the crankcase half.

– Screw nut onto the stud and

tighten it by hand

: Turn spindle (1)

counterclockwise until the

crankcase half rests against the

guide sleeves

2410RA121 TG2410RA122 TG

Ensure that the guide

sleeves (arrows) line up with the

holes and that the housing gasket is

not jammed or buckled.

– Continue turning the spindle of

the assembly tool until the gap

between the halves of the

crankcase is closed

– Unscrew nuts

– Turn the spindle clockwise to

remove the assembly tool

– Remove the two M5x72 screws

which were fitted to prevent

twisting

: Insert the screws (arrows) and

tighten them down crosswise

2410RA119 TG2410RA107 TG

46 MS 241 C

– For versions with quick chain

tensioner, fit side plate

: Coat screw (1) with Loctite,

screw in and tighten, b 16

: Fit the circlip (1)

– Examine and install the piston,

b 6.7

– Examine and install the cylinder,

b 6.5

– Install chain tensioner, b 5.7

– Reassemble remaining parts in

reverse order

2410RA545 TG

2410RA123 TG

6.6.1 Ball bearing / crankcase

The two halves of the crankcase

can be replaced individually if they

are defective.

New crankcases are delivered with

the relevant components pre-

assembled

– see spare parts list

Those parts which are not supplied

with the new crankcase must be

removed from the old crankcase,

examined and replaced if

necessary.

When fitting a new crankcase, the

machine's serial number must be

stamped on the crankcase with

2.5 mm figure stamps.

If the original crankcase is reused,

the oil seals and grooved ball

bearings must be replaced, all

gasket residues removed and the

mating surfaces cleaned

thoroughly. The mating surfaces

must be absolutely flawless and

clean to guarantee a perfect seal,

b 16.

Examine both halves of the

crankcase for cracks and check all

mating surfaces for signs of

damage.

– Refer also to troubleshooting,

b 3.7

– Remove crankshaft, b 6.6

– Wear protective gloves

– risk of burns

Ignition-side half of the

crankcase

: Carefully drive the oil seal out

with a punch

: Examine and clean the

crankcase, replace if necessary.

– Replace ball bearings if the

crankcase is in good condition

– Heat the bearing seat of the ball

bearing to approx. 150 °C

(300 °F)

The bearing (1) drops out of its own

accord when this temperature is

reached.

2410RA124 TG2410RA125 TG

47MS 241 C

Installation

– Heat the bearing seat of the ball

bearing to approx. 150 °C

(300 °F)

– Position ball bearing so that the

open side (balls visible) faces the

inside of the crankcase

: Press the grooved ball bearing

home as far as possible

The ball bearing must be fitted

rapidly, as it absorbs heat and

expands.

– Check seat of ball bearing, if

necessary, use press arbor

1118 893 7200 to press the ball

bearing fully home in the ball

bearing seat

Clutch-side half of the crankcase

: Carefully drive the oil seal out

with a punch

– Examine and clean the

crankcase, replace if necessary.

2410RA126 TG2410RA127 TG

– Replace ball bearings if the

crankcase is in good condition

– Heat the bearing seat of the ball

bearing to approx. 150 °C

(300 °F)

The bearing (1) drops out of its own

accord when this temperature is

reached.

Installation

Because the clutch side half of the

crankcase does not have a fixed

bearing seat, the oil pump must be

removed beforehand

– The oil pump serves as a

reference

– Install oil pump, b 12.3

– Heat the bearing seat of the ball

bearing to approx. 150 °C

(300 °F)

– Position ball bearing so that the

centering ring (arrow) points

towards the oil pump

: Press ball bearing fully home (oil

pump)

2410RA128 TG

2410RA129 TG

The ball bearing must be fitted

rapidly, as it absorbs heat and

expands.

– Check seat of ball bearing, if

necessary, use press arbor

1118 893 7200 to carefully press

the ball bearing fully home until it

rests against the oil pump

– Remove oil pump, b 12.3

– Install crankshaft, b 6.6

– Install the oil seals, b 6.3

– Reassemble remaining parts in

reverse order

6.7 Piston

Before removing the cylinder,

decide whether the crankshaft is to

be removed, b 6.6

– Remove the cylinder, b 6.5

The clutch side snap ring is not

removed.

: Pry the hookless snap ring out of

the recess (arrow) on the ignition

side with a suitable tool

2410RA130 TG

48 MS 241 C

: Push assembly drift (1)

1110 893 4700 through the

installed snap ring

: Push the piston pin (2) out of the

piston with the assembly drift (1)

1110 893 4700

If the piston pin is stuck, tap the end

of the drift gently with a hammer to

loosen it.

The piston must be held steady

during this process to ensure that

jolts are not transmitted to the

connecting rod.

– Remove the piston

– Examine the piston rings and

replace if necessary, b 6.8

: Take out the needle bearing (1),

examine and clean it, replace if

necessary

2410RA131 TG

2410RA132 TG

Installation

– Coat needle bearing with oil and

slide it into the rod eye

Line up the piston so that the

arrow (arrow) in the piston base

points towards the spiked

bumper (exhaust port)

The assembly drift can be inserted

through the fitted snap ring.

– Position the piston on the rod eye

: Push assembly drift (1)

1110 893 4700 with the stub end

first through piston hole and rod

eye (needle cage) and secure

the piston

– Coat the piston pin (1) with oil

: Fit the piston pin (1) on the stub

of the assembly drift (2) and slide

it into the piston

2410RA133 TG

2410RA134 TG

: Remove the sleeve (1)

5910 893 1707 from the installing

tool (2) 5910 890 2210

: Attach the snap ring (1) to the

magnet (2) and align it so that the

snap ring gap is on the flat

side (arrow)

: Push the slotted opening of the

sleeve over the magnet and snap

ring

The inner pin (1) must point towards

the flat face of the tool's shank (2).

5904RA089 TG

165RA153 TG

5904RA090 TG

49MS 241 C

Press the assembly tool down in the

sleeve until the magnet is at the end

of the guide slits.

: Remove sleeve and fit it over the

opposite shaft end of the

assembly tool, with the internal

pin pointing towards the flat

surface.

The snap ring (1) must be fitted so

that the gap in the ring (arrow)

points upwards in axial direction of

the piston.

5904RA091 TG

216RA178 TG

2410RA135 TG

: Position the installing tool

5910 890 2210 with the taper

sleeve on the piston boss, hold

the piston steady and press the

tool shank home until the snap

ring slips into the groove

The tool must be precisely aligned

in axial direction of the piston pin.

– Examine the piston rings and

replace if necessary, b 6.8

– Install the cylinder, b 6.5

– Reassemble remaining parts in

reverse order

2410RA136 TG2410RA137 TG

6.8 Piston rings

– Remove piston, b 6.7

– Remove piston rings from piston

: Use a piece of old piston ring to

scrape the grooves (arrows)

clean

: Align the new piston rings so that

the radiuses at the ends of the

ring (arrows) face upwards

2410RA138 TG2410RA139 TG

50 MS 241 C

– Carefully slide the piston rings

over the piston

– danger of breakage

: Position the piston rings so that

the radiuses at the ring gaps

encircle the fixing pins in the

piston grooves (arrows)

: Check the correct installed

position of the piston rings

again (arrows)

– Install the piston, b 6.7

– Reassemble remaining parts in

reverse order

2410RA140 TG

6.9 Decompression valve

– Remove shroud, b 6.4

: Unscrew decompression

valve (1)

: Examine the sealing

cone (arrow) on the

decompression valve for signs of

damage

– Use a new decompression valve

if the sealing cone on the

decompression valve does not

seal tightly or is damaged

– Fit the decompression valve by

hand and screw it in

– Screw the decompression valve

tight

– Reassemble remaining parts in

reverse order

2410RA141 TG

5902RA164 TG

51MS 241 C

7. Ignition system

Exercise extreme caution while

carrying out maintenance and repair

work on the ignition system. The

high voltages which occur can

cause serious or fatal accidents.

Troubleshooting on the ignition

system should always start with the

spark plug, b 3.5

– Remove fan housing, b 9.2

The contactless electronic ignition

system basically consists of a

control unit (1), flywheel (2),

switchgear (3) and solenoid

valve (4).

The ignition module accommodates

all the components required to

control the ignition timing and fuel

flow. There are only three electrical

connections leaving the control unit:

1. High voltage output for the

ignition lead.

2. Connector tab for black

lead – short circuit wire.

3. Connector tab for red lead

– M-Tronic.

2410RA142 TG

Testing of the ignition module is not

limited to only a spark test. If no

ignition spark is obtained or other

functions do not work, a diagnosis

must be carried out according to the

troubleshooting chart; replace

control unit or M-Tronic wiring

harness if necessary.

7.1 Ignition timing

Ignition timing is fixed and cannot

be adjusted during repair work.

Since there is no mechanical wear

in these systems, ignition timing

cannot get out of adjustment during

operation.

7.2 Pre-separator

– Remove fan housing, b 9.2

: Remove screw (1)

: Remove pre-separator (2), check

and replace if necessary

– Reassemble parts in reverse

order

2410RA143 TG

7.3 Control unit

– Remove fan housing, b 9.2

– Unplug the spark plug boot

: Remove holders (1) and (2)

carefully from the slits (arrows)

and open

: Pull the ignition lead (3) out of the

guide

: Lift retaining tab (arrow) and

remove angled plug (1)

– Examine insulating sleeve of the

angled plug, clean or replace if

necessary, b 7.7.2

2410RA144 TG

2410RA145 TG

52 MS 241 C

: Remove screws (1) with washers

– Remove control unit

: Remove wiring harness (1) and

ground wire (2) from the

guides (arrows) and remove

cable holder (3)

– Check ignition lead, replace if

necessary

– Examine the spark plug boot,

replace if necessary, b 7.5

– Troubleshooting, b 3.5

2410RA146 TG

2410RA147 TG

Installation

: Position cable holder (1) on the

cylinder and secure it with the

pins on the cylindrical raised

parts

: Hold cable holder (1) against

cylinder and position control

unit (2)

: Insert screw (3) with washer – do

not tighten

On the cable lug of the ground wire,

the crimped side must face the

screw head.

2410RA148 TG

2410RA149 TG

: Position ground wire (1) so that

the cable lug is pressed fully

home (arrow) and the crimped

side faces the screw head

: Insert screw (2) with washer – do

not tighten

: Push back ignition module and

slide setting gauge (1)

1111 890 6400 between the legs

of the ignition module and the

magnetic poles of the flywheel

2410RA150 TG

2410RA151 TG

53MS 241 C

Shown without setting gauge for a

better view.

– Flywheel must turn freely

: Turn the flywheel until the

magnet poles "N/S" (arrows) are

at the control unit (1)

: Press control unit (1) against the

setting gauge and tighten

screws (2) – the cable lug of the

ground wire must be fully seated

– Remove the setting gauge

– Checking correct functioning

– Turn the flywheel: it must not

touch the control unit

: Press ground wire (1) completely

into the guide (arrow)

– Ground wire is routed

underneath the wiring harness

2410RA152 TG

2410RA153 TG

: Orient angled plug (1) so that the

retaining tab (2) faces the muffler

: Press the angled plug (1) straight

onto the connector tags until the

retaining tab (2) snaps into place

– Do not insert the angled plug on

a slant or tilt it

Protective tube (2) must be

positioned snug against the

grommet in the air guide shroud.

: Press the wiring harness (1) into

the guide so that the protective

tube (2) a = ca. 8 mm is seated in

the guide (arrow)

– Ground wire is routed

underneath the wiring harness

: Push the holder (3) into the slit of

the cable holder (4) until it clicks

into place

2410RA154 TG

2410RA155 TG

: Orient wiring harness (1) so that

the protective tube (2) lines up

with the leading edge (arrow) and

the red M-Tronic lead is

underneath the short-circuit

wire (black)

: Press wiring harness (1)

completely into the

guides (arrows)

: Plug the spark plug boot (1) onto

the spark plug so that it runs

parallel to the air guide shroud

underneath the tab (2)

2410RA156 TG

2410RA157 TG

2410RA158 TG

54 MS 241 C

: Press ignition lead (1) completely

into the guide (arrow)

– Note routing of the ignition lead,

see illustration

Ignition lead and spark plug boot

must not touch the air guide shroud.

: Press the holder (1) into the

slit (arrow) until it clicks into place

– Reassemble remaining parts in

reverse order

2410RA159 TG

2410RA160 TG

7.4 Spark test check control

unit

The ignition test refers only to a

spark test, not the general functions

of the control unit; these are

described in the M-Tronic chapter,

b 8.2, b 8.5.

To spark test the control unit, use

either the ZAT 4 ignition system

tester 5910 850 4503 or the

ZAT 3 ignition system tester

5910 850 4520.

Using the ZAT 4 ignition system

tester 5910 850 4503

– Before starting the test, install a

new spark plug in the cylinder

and tighten it down firmly.

: Connect the spark plug boot to

the input terminal (1). Push the

tester's output terminal (3) onto

the spark plug

Danger! High voltage – risk of

electrocution.

– Crank the engine quickly with the

rewind starter and check

sparkover in the window (2) of

the ignition system tester

165RA183 TG

The engine may start and

accelerate during the test.

If a spark is visible, the ignition

system is in order.

– If no spark is visible in the

window (2), check the ignition

system with the aid of the

troubleshooting chart, b 7.8,

b 8.5

Using the ZAT 3 ignition system

tester 5910 850 4520

– Before starting the test, install a

new spark plug and tighten it

down firmly

: Connect the spark plug boot to

the terminal (2)

: Attach ground terminal (1) to the

spark plug

: Use adjusting knob (4) to set

spark gap to approx. 2 mm,

see window (3)

165RA184 TG

3 4

55MS 241 C

While using the ZAT 3, hold it only

by the handle (4) or position it in a

safe place. Keep fingers or other

parts of your body at least 1 cm

away from the spark window (3),

high-voltage connection (2), ground

connection (5) and the ground

terminal (1).

Danger! High voltage – risk of

electrocution.

– Crank the engine quickly with the

rewind starter and check

sparkover in the window (3) of

the ignition system tester

The engine may start and

accelerate during the test.

If a spark is visible in the

window (3), the ignition system is in

order.

– If no spark is visible in the

window (3), check the ignition

system with the aid of the

troubleshooting chart, b 7.8

7.5 Spark plug boot

– Remove shroud, b 6.4

– Unplug spark plug boot and pull

ignition lead out of the guides,

b 7.3

165RA185 TG

3 4

: Use suitable pliers to pull the

torsion spring out of the spark

plug boot

– Unhook the torsion spring from

the ignition lead

– Pull the boot off the ignition lead

– Check ignition lead, replace if

necessary, b 7.5.1

Installation

– With a new ignition module, use a

pointed tool to pierce the center

of the new lead's insulation

approx. 13 mm from the end of

the ignition lead

: Pinch the hook of the torsion

spring into the center of the

ignition lead (arrow) where it has

been pierced

2310RA127 TG

165RA188 TG

– Apply STIHL press fluid to the

inside of the spark plug boot,

b 16

: Push the ignition lead and torsion

spring into the spark plug boot

: Ensure that the torsion

spring (arrow) is located in the

recess

– Plug spark plug boot onto spark

plug and press ignition lead

completely into the guide, b 7.3

Ignition lead and spark plug boot

must not touch the air guide shroud.

– Reassemble remaining parts in

reverse order

2310RA128 TG2310RA129 TG

56 MS 241 C

7.5.1 Ignition lead

The ignition lead is built into the high

voltage output of the control unit. If

the ignition lead is damaged, the

control unit must be replaced.

– Remove spark plug boot, b 7.5

– Remove the control unit, b 7.3

: Pull grommet (1) off of high-

voltage output (arrow)

: Twist ignition lead (2) out of

control unit

– Pull the grommet off the ignition

lead

: Use a pointed tool to pierce the

center of the end of the new

ignition lead, which is to be

twisted into the control unit.

2410RA161 TG

165RA191 TG

– Before twisting in the ignition

lead, fill the coil tower with STIHL

multi-purpose grease, b 16

Do not use either graphite grease or

silicone insulating paste.

– Push grommet onto ignition lead

: Twist ignition lead (2) into control

unit

: Push on the grommet (1)

– Install control unit and adjust air

gap control unit/ flywheel, b 7.3

– Reassemble remaining parts in

reverse order

7.6 Flywheel

For versions with ErgoStart, the new

puller 5910 890 4504 with extended

clamping bridge must be used. The

previous puller 1135 890 4500 is

being replaced by the new puller,

but can still be used for the standard

versions.

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

2410RA162 TG

– Block the piston with the locking

strip, b 4

: Unscrew the flywheel nut (1)

: Screw the screws (1) of the

puller (3) 5910 890 4504 into the

flywheel as far as they will go

– Ensure that the screws are

screwed in uniformly

– For versions with heating, only M

5 x 25 screws can be used to

fasten the puller

– Generator can be damaged

– For versions with ErgoStart, do

not damage the pawls

: Turn screw (2) clockwise until the

flywheel comes off the crankshaft

stub

: Unscrew puller (3)

5910 890 4504 from flywheel

2410RA164 TG

2410RA163 TG

57MS 241 C

The flywheel and magnet

poles (arrows) must not display any

signs of damage or blue

discoloration; replace flywheel if

necessary.

– The magnet ring must also be

examined for signs of damage in

versions with handle heating,

b 7.6

– With versions with ErgoStart

pawls, check for damage and

smoothness of motion, b 9.4.

Installation

Flywheel and crankshaft stub must

be free from grease for installation.

Ensure that the machined key

(arrow) engages the slot in the

crankshaft.

– Set the air gap between control

unit and flywheel, b 7.3

0001RA167 TG2310RA110 TG

– Reassemble remaining parts in

reverse order

7.7 Short circuit wire

Ground wire, short-circuit wire and

M-Tronic lead are all combined into

one wiring harness.

Make a contact test of the short

circuit wire if the spark plug and

ignition lead with spark plug boot

are in order.

7.7.1 Contact test

– Remove fan housing, b 9.2

– Move the Master Control lever to

– Blade receptacle of the short-

circuit wire must touch the

contact spring (arrow) in position

Also carry out a contact and

continuity test of the ground wire

between cable lug and contact

spring, replace wiring harness if

necessary.

– If no fault can be found, test the

M-Tronic in accordance with flow

chart, b 7.8

– Reassemble parts in reverse

order

2310RA155 TG

7.7.2 Removal and installation

– Remove shroud, b 6.4

– Unplug the spark plug boot

– Remove fan housing, b 9.2

– Remove choke rod, b 11.4

: Remove holders (1) and (2)

carefully from the slits (arrows)

and open

: Lift retaining tab (arrow) and

remove angled plug (1)

2410RA165 TG

2410RA166 TG

58 MS 241 C

: Remove screw (1) with washer

and remove ground wire cable

lug (2)

: Remove wiring harness (1) and

ground wire (2) from the

guides (arrows)

Versions with heating

: Pull out carburetor heating

lead (1) at the guide (arrow)

2410RA167 TG

2410RA168 TG

2410RA169 TG

: Remove blade receptacle (1) of

the carburetor heating lead

Versions with manual fuel pump

: Push out the holder (1) with the

fuel pump at the air guide

shroud (2), remove fuel hose (3)

at the carburetor (arrow) and lay

it on top of the air guide shroud

All versions

– Remove filter base, b 13.3

– Remove contact spring, b 7.7.4

– Remove switch shaft on filter

base, b 11.1

2410RA170 TG

2410RA220 TG

: Pull plug connector (1) out of the

carburetor support mount (arrow)

: Hold the jack (1), press the

tab (arrow) and pull out the

plug (2) – do not tug on the leads

– Turn the carburetor a little in the

direction of the control handle

– Do not overextend fuel hose

: Remove the plug (1)

2410RA171 TG

2410RA172 TG

2 1

2410RA173 TG

59MS 241 C

: Remove diagnostic jack (1) with

connector housing (2) from the

guides (arrows)

: Pry out and remove the cable

holder (1) at the pin (arrow)

: Remove wiring harness (1) from

the guides (arrows) of the air

guide shroud

2410RA174 TG

2410RA175 TG

2410RA176 TG

: Pull out grommet (1) with wiring

harness

: Remove ground wire (1) from the

guides (arrows)

: Remove ground wire (1) from the

guide (arrow)

: Remove the switch shaft (2)

2410RA177 TG

2410RA178 TG

2410RA179 TG

: Pull the retaining tab (1) in the

direction of the leads and open

the cover (2)

: Pull blade receptacles (1) out of

the insulating sleeve (2)

– Check blade receptacles and

insulating sleeves, clean or

replace insulating sleeves if

necessary

With a new wiring harness, the

grommets and the plugs as well as

the insulating sleeve are pre-

assembled.

2410RA180 TG

2410RA181 TG

60 MS 241 C

Installation

: Push the blade receptacle (1) of

the red lead (M-Tronic) into the

rear receptacle (arrow) of the

insulating sleeve (2)

– Crimped side faces forward

The leads must not be reversed.

: Push the blade receptacle (1) of

the black lead (short-circuit wire)

into the front receptacle (arrow)

of the insulating sleeve (2)

– Crimped side faces forward

The leads must not be reversed.

2410RA182 TG

2410RA183 TG

: Close and lock the cover (1) so

that the tab (2) engages the

slit (arrow) of the retaining tab (3)

– the retaining tab must fit snugly

against the insulating sleeve

The protective tube (1) must rest

against the grommet (2).

: If necessary, push the wiring

harness towards the grommet (2)

until the protective tube (1) rests

against the grommet (2)

: Orient the wiring harness (1) so

that the protective tube (2) and

angled plug (3) face the control

unit

2410RA184 TG

2410RA185 TG

2410RA186 TG

The ground wire (4) must be routed

behind the protective tube (2)

– facing the cylinder.

: Push the grommet (1) into the

opening (arrow) in the air guide

shroud (2) until it is flush with the

edge of the air guide shroud

: Orient wiring harness so that the

red lead (1) is above and the

black lead (2) is underneath the

ground wire (3)

Starting at the protective tube (4),

the ground wire branches out into a

thin black lead (M-Tronic) and a

thick blue lead (short-circuit wire).

When inserting the ground wire, the

small guide rib (arrow) must be

between these two leads

2410RA187 TG

2410RA189 TG

61MS 241 C

: Press the red M-Tronic lead (1),

ground wire (2) and black

lead (3) of the short-circuit wire

all the way into the

guides (arrows)

The protective tube (4) must start at

the beginning of the rib and

protective tube (5) must rest against

the beginning of the rib.

: Slide cable holder (1) with the

hinge into the slot (arrow) of the

air guide shroud

: Turn the cable holder (1) towards

the cylinder and position it

2410RA190 TG

3 2

2410RA191 TG

: Check that the leads are properly

seated in the guides and press

the cable holder (1) with the

pin (arrow) into the mount until it

snaps into place

: Orient diagnostic jack (1) so that

the black leads (2) face the

control handle

: Press diagnostic jack (1) and

connector housing (3) into the

guides (arrows)

2410RA192 TG

2410RA193 TG

: Press the diagnostic jack (1) into

the mount so that it is seated

completely in the recess (arrows)

and the tabs (2) snap into place

: Press plug (1) into the mount as

far as it will go

: Using wiring tool 5910 890 4000,

press the blue ground wire (1)

and black short-circuit wire (2)

into the guide (arrow) so that the

wires are snug against the air

guide shroud

2410RA194 TG

2410RA195 TG

2410RA196 TG

62 MS 241 C

: Orient plug (1) and jack (2) that

the tab (3) lines up with the

mount (arrow) – do not twist the

leads

: Plug connector (1) into jack (2)

until the tab (3) clicks into place in

the mount (arrow)

: Press the plug connection (1)

into the mount (2) of the

carburetor support so that the

tab (arrow) engages in the recess

of the plug connection

– Push on the carburetor and

observe cable routing as well as

installation position of the

M-Tronic and, if present, the

heating system, b 8.4

2410RA188 TG

1 2

2410RA197 TG

: Slide the blade receptacle (1) of

the blue ground wire, with the

crimped side facing the cam (2),

into the guide (arrow) as far as it

will go

: Hook ground wire (1) into the

guides (arrows)

– Push switch shaft onto filter base,

b 11.1

– Install contact spring, b 7.7.4

– Install filter base, b 13.3

2410RA199 TG

2410RA200 TG

: Check the routing of the blue

ground wire (1) and black short-

circuit wire (2), if necessary,

press them completely into the

guide (arrow) using wiring tool

5910 890 4000 – wires must rest

snug against the air guide shroud

: Using wiring tool 5910 890 4000,

press the blue ground wire (1)

and black short-circuit wire (2)

into the guides so that the

markings (arrows) are located at

the guide ribs

– Conduct a function test of the

switch shaft, b 11.1

2410RA201 TG

2410RA202 TG

63MS 241 C

Versions with heating

: Orient blade receptacle (1) so

that the crimped side faces the

carburetor

: Press blade receptacle (1) onto

the connector tab (arrow) of the

heating switch as far as it will go

: Press carburetor heating lead (1)

completely into the guide (arrow)

Versions with manual fuel pump

: Push the holder (1) with the fuel

pump into the recess in the air

guide shroud (2) as far as it will

2410RA198 TG

2410RA169 TG

2410RA226 TG

: Press fuel return line (3)

completely into the guide (arrow)

Push the new fuel suction hose (1)

completely onto the

connectors (arrows)

All versions

Ground wire: Crimped side of the

cable lug (1) must be visible.

: Position cable lug (1) between

control unit (2) and stop (3)

: Insert screw (4) with washer and

tighten

2410RA227 TG2410RA203 TG

42 3

: Press ground wire (1) completely

into the guide (arrow)

– Ground wire is routed

underneath the wiring harness

: Orient angled plug (1) so that the

retaining tab (2) faces the muffler

: Press the angled plug (1) straight

onto the connector tags until the

retaining tab (2) snaps into place

– Do not insert the angled plug on

a slant or tilt it

2410RA204 TG

2410RA205 TG

64 MS 241 C

Protective tube (2) must be

positioned snug against the

grommet in the air guide shroud.

: Press the wiring harness (1) into

the guide so that the protective

tube (2) a = approx. 8 mm is

seated in the guide (arrow)

– Ground wire is routed

underneath the wiring harness

: Push the holder (3) into the slit of

the cable holder (4) until it clicks

into place

: Orient wiring harness (1) so that

the protective tube (2) lines up

with the leading edge (arrow) and

the red M-Tronic lead is

underneath the short-circuit

wire (black)

2410RA155 TG

2410RA206 TG

: Press wiring harness (1)

completely into the

guides (arrows)

– Check the air gap between

control unit and flywheel, adjust if

necessary, b 7.3

Ignition lead (1) must be seated

completely in the guide.

: Press the holder (2) carefully into

the slit (arrow) until it clicks into

place

– Conduct a function test of the

switch shaft, b 11.1

– Reassemble remaining parts in

reverse order

7.7.3 Ground wire

Testing and installation of ground

wire is the same as for the short-

circuit wire

– Check contacts and operation,

b 7.7

2410RA207 TG

2410RA208 TG

7.7.4 Contact spring

The short-circuit wire must be

seated firmly in the eye of the

contact spring, if necessary, carry

out a contact and continuity test,

b 7.7.1.

– Remove the filter base from the

studs, b 13.3

: Turn filter base (1) to the side

: Lift contact spring (1) slightly and

guide it over the tab (arrow)

: Press contact spring (1) out of

the guides in the filter base (2)

2410RA209 TG

2310RA151 TG

65MS 241 C

: Press contact sleeve (1) of the

short-circuit wire out of the

contact spring (2)

– Examine contact spring, replace

if necessary

Installation

: Push the contact sleeve (1) of the

short-circuit wire into the

eye (arrow) of the contact

spring (2) as far as it will go

2410RA210 TG

2410RA211 TG

: Position contact spring (1)

against the guide (arrows)

: Lift contact spring (1) slightly at

the connection of the short-circuit

wire and guide it over the tab (2)

– do not overextend the contact

spring

Before pushing the contact

spring (1) all the way in, lift it slightly

and guide it over the switch shaft –

2 mm maximum.

2410RA212 TG

2310RA153 TG

: Push the contact spring (1) into

the guide (arrows) as far it will go,

until the tab surrounds the

contact spring

– Install filter base, b 13.3

: Checking correct functioning

– Blade receptacle of the short-

circuit wire must touch the

contact spring (arrow) in position

– Reassemble remaining parts in

reverse order

2310RA154 TG

2310RA155 TG

66 MS 241 C

7.8 Troubleshooting, ignition system

Engine does not run

Stop switch:

– in position "

F"?

Check spark plug:

– Smeared with oil, black?

– Sooted?

– Electrode gap correct?

– Contacts shorted (threads)?

– Clean, adjust or replace spark plug,

b 7.5

Check spark plug boot:

– Firmly seated on spark plug (torsion

spring)?

– Torsion spring hook in center of ignition

lead?

– Spark plug boot damaged?

– Replace spark plug boot and/or torsion

spring if necessary,

b 7.5

Check ignition:

with ZAT 3 or ZAT 4

(use ZAT 3 as main spark gap

see TI 32.94),

b 7.4

67MS 241 C

Check flywheel:

– Have pole shoes turned blue?

– Replace flywheel if necessary,

b 7.6

Air gap:

– Check control unit/ flywheel,

– adjust if necessary, b 7.3

Check ignition lead:

– Severe chafing?

– Spark plug boot: Holes / cracks?

– Resistance of spark plug boot to ground:

Required 1.5...12 kΩ

– Check resistance of spark plug lead to

ground, (spark plug boot and control unit have

been removed)

Value: Required < 10 Ω,

replace spark plug boot and/or ignition module

if necessary,

b 7.5.1

Check short circuit wire:

– Wire damaged?

– Plug connections firmly seated?

– Check continuity, replace wiring harness if

necessary, b 7.7.1

yes

Spark

present?

68 MS 241 C

Engine runs smoothly,

troubleshooting procedure

completed

Control unit

needs to be replaced,

b 7.3

yes

– Look for fault in fuel or carburetor

system

– Check engine for leaks

– Check position of flywheel on

crankshaft,

b 3.6, b 6.2

yes

Switch shaft

Check correct operation:

– Short circuit wire chafed?

– Function between contact spring and

contact of the switch shaft:

– Position "

F" = no connection

– Position "

0" = connection

– Replace wiring harness if necessary,

b 11.1

Spark

present?

Machine

runs?

69MS 241 C

8. M-Tronic

The fully electronic M-Tronic engine

management system controls the

ignition timing and fuel flow, taking

all external conditions into account.

A basic or standard setting of the

carburetor is no longer required.

The M-Tronic electronically adjusts

the fuel-air mixture in the carburetor.

The M-Tronic controls all operating

states such as start, idle, part

throttle and full throttle while

accounting for the external

conditions, e.g., use at varying

attitudes, as well as changing

temperatures or fuel quality – the

carburetor does not have any

adjusting screws.

Troubleshooting and test

procedures are described in the

following chapters, Testing, b 8.2,

Troubleshooting, b 8.5.

2410RA546 TG

8.1 Calibrating the control

unit

If the outstanding running behavior

and usual performance or maximum

speed of the engine can no longer

be attained, the usual engine

performance can be attained again

by calibrating the control unit.

A regulating cycle only starts if the

machine is operated for

approximately 2 seconds under

constant conditions.

If the maximum speed is not

reached...

– Examine air filter, clean or

replace if necessary, b 13.1

– Examine the spark arresting

screen (if installed); clean or

replace it if necessary, b 6.1

– Check chain tension, adjust if

necessary

– Check chain lubrication

– Set Master Control lever to

Start }

– Start engine and let it warm up

– Carry out five uniform cuts to

length

– speed between 8000 rpm and

11200 rpm, log diameter

approx. 30 cm

– If the outstanding running

behavior and the usual

performance are not attained,

continue troubleshooting and test

procedures as described under

Testing, b 8.2,

Troubleshooting, b 8.5

If the control unit or carburetor is

replaced during servicing...

– Remove the saw chain and guide

bar

– Reinstall the chain sprocket

cover

– Set Master Control lever to

Start }

– Start machine – do not blip the

throttle trigger

After completion of the following

procedure, the Master Control lever

must be moved from Start } to

STOP 0 without pressing the throttle

trigger.

– Let the machine warm up for at

least 60 seconds in the Start }

position and then move the

Master Control lever to STOP 0

– Calibration is completed

The control unit is adjusted to the

carburetor while the engine runs in

the position Start }.

The machine must be switched off

immediately for the information to

be stored in the control unit.

70 MS 241 C

8.2 Testing

8.2.1 Test preparations

The following steps must be carried

out before testing.

– Carry out troubleshooting

according to troubleshooting

chart, b 8.5

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

– Remove coarse dirt from around

the screwed connections, control

unit, switchgear, solenoid valve

and diagnostic jack

8.2.2 Connect the test lead

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

: Remove the plug (1)

2410RA173 TG

: Remove diagnostic jack (1) from

the guide (arrow)

: Orient the plug (1) of the

M-Tronic test lead

5910 840 0903 so that the

angled shapes (arrows) match

between diagnostic jack (2) and

plug (1)

: Push the plug (1) of the

M-Tronic test lead

5910 840 0903 into the

diagnostic jack (2) as far as it will

– After completion of the test

procedure, unplug the test lead

from the diagnostic jack

2410RA213 TG

2410RA214 TG

1 2

2410RA215 TG

: Press the diagnostic jack (1) into

the mount (arrow) until it is fully

home

– Reassemble remaining parts in

reverse order

8.2.3 Check screwed and plug

connections as well as

switch

– Carry out test preparations,

b 8.2.1

There must be a reliable connection

for communication between control

unit, switching device and solenoid

valve. If communication between

control unit and solenoid valve is

interrupted or faulty, the control unit

does not initiate an ignition spark.

– In the event of a malfunction or if

there is no ignition spark, first

check the plug connections and

wiring harness between control

device and solenoid valve

2410RA216 TG

71MS 241 C

Screw (1) must be tight.

Leads (arrows) must be seated

completely and firmly in the blade

receptacles and the cable lug.

Plug connection (1) must be

pressed together completely –

locking lug (3) must engage the

recess.

: If necessary. remove the plug

connection (1) from the

mount (arrow), remove the

plug (2) and check the contacts,

b 8.2.3

2410RA217 TG

2410RA218 TG

Versions with heating

: Remove blade receptacle (1) and

contact sleeve (2)

: Push out the holder (3) with

ground wire (4) at the air guide

shroud (5) and lay it aside

Versions with manual fuel pump

: Push out the holder (1) with the

fuel pump at the air guide

shroud (2), remove fuel hose (3)

at the carburetor (arrow) and lay

it on top of the air guide shroud

2410RA219 TG

2410RA220 TG

All versions

Plug (1) must be seated completely

and firmly in the recess of the

solenoid.

: If necessary, remove plug (1) and

check contacts

: Set Master Control lever (1) to

position }; the cam on the

lever (2) must actuate the

microswitch (arrow) – clicking

sound

– If the microswitch is not actuated

by the lever at the carburetor,

replace lever if necessary,

b 13.6.6

– If the microswitch does not

function although it was actuated,

then the switchgear must be

replaced, b 8.4

2410RA221 TG

2410RA222 TG

72 MS 241 C

Versions with heating

: Push the holder (1) with the

ground wire (2) into the recess in

the air guide shroud (3) as far as

it will go

: Push ground wire (2) into the

guide (arrow)

: Push contact sleeve (1) into

heating switch

– Push in contact sleeve

completely

: Press lead (2) completely into the

guide (arrow)

2410RA223 TG

2410RA224 TG

: Push blade receptacle (1) onto

the connector tab

– Push on blade receptacle all

the way

: Press lead (2) completely into the

guide (arrow) of the filter base

Versions with manual fuel pump

: Push the holder (1) with the fuel

pump into the recess in the air

guide shroud (2) as far as it will

: Press fuel return line (3)

completely into the guide (arrow)

2410RA225 TG

2410RA226 TG

: Push the new fuel suction

hose (1) completely onto the

connectors (arrows)

– Reassemble remaining parts in

reverse order

8.2.4 Checking the solenoid

valve

– Carry out test preparations,

b 8.2.1

– Check screwed and plug

connections, b 8.2.3

– Check contacts and operation,

b 8.2.5

– Move the Master Control lever to

position "F"

– Connect the test lead, b 8.2.2

2410RA227 TG

73MS 241 C

Measuring resistance

: Measure resistance between

plugs (1) and (2) of the M-Tronic

test lead

Target value: between 28 and

42 ohms

– If the target value is not attained,

check electrical leads for

interruption, e. g., due to cable

breakage between solenoid

valve and diagnostic jack, or

contact due to damaged

insulation

8.2.5 Checking the start

detection function

– Carry out test preparations,

b 8.2.1

– Check screwed and plug

connections, b 8.2.3

2410RA228 TG

: Set Master Control lever (1) to

position }; the cam on the

lever (2) must actuate the

microswitch (arrow) – clicking

sound

Versions with manual fuel pump

– Push out the holder with the fuel

pump and set it aside, b 8.2.3

Versions with heating

– Disconnect leads, push out the

holder with the heating switch

and set it aside, b 8.2.3

All versions

: Disconnect the plug (1) from the

solenoid valve (2) – the solenoid

valve must not be twisted; if

necessary, hold the solenoid

valve in place when

disconnecting the plug

2410RA222 TG

2410RA229 TG

: Lift retaining tab (arrow) and

remove angled plug (1)

– Check angled plug, dismantle

and clean if necessary, b 7.7.2

– Set Master Control lever to

position }

– Connect the test lead, b 8.2.2

2410RA166 TG

74 MS 241 C

– Connect M-Tronic test lead to

multimeter

: Insert black plug (1) in the "com"

/ "ground" jack and the red

plug (2) in the "volt" / "ohm" jack

– Set multimeter to "diode test"

: Test diode on

switchgear (3) (microswitch) in

accordance with multimeter

instruction manual

If the switchgear (microswitch) is

intact and the Master Control lever

is set to the } position, the

following target values will be

attained:

– Measurement in direction of flow,

target value: 0.3 volts to 0.7 volts

– Move the Master Control lever to

position F

– Measurement in direction of flow,

required: 1.2 volts to infinity

– Observe display, e.g., (O.L.)

or (1.)

– If the required values are not

attained, replace switchgear and

repeat test procedure, b 8.4

– If the required values are not

attained again, replace wiring

harness; it may be possible to

reuse the previous switchgear,

b 7.7.2

2410RA230 TG

Versions with manual fuel pump

– Install holder with fuel pump,

push new fuel hose onto

connector and press fuel return

line into the guide, b 8.2.3

Versions with heating

– Install holder with heating switch,

press leads in and on and into the

guides, b 8.2.3

– Reassemble remaining parts in

reverse order

8.2.6 Checking the wiring

harness

– Carry out test preparations,

b 8.2.1

– Check contacts and operation,

b 8.2.3

– Set Master Control lever to

position STOP 0

: Lift retaining tab (arrow) and

remove angled plug (1)

– Check angled plug, dismantle

and clean if necessary, b 7.7.2

2410RA166 TG

Checking the ground connection

: Measure the resistance between

blade receptacle (1) with black

lead and screw (2) at the control

unit

Target value: < 10 ohms.

: Measure the resistance between

contact spring (1) and screw (2)

at the control unit

Target value: < 10 ohms.

If the target values are not

attained

– Check electrical leads for

interruption, e. g., cable

breakage – if necessary, replace

wiring harness, b 8.2.6

2410RA231 TG

2410RA232 TG

75MS 241 C

Check leads between control unit

and diagnostic jack

– Connect the test lead, b 16

: Measure the resistance between

blade receptacle (1) with red lead

and black plug (2) of the

diagnostic cable

Target value: < 10 ohms.

: Measure the resistance between

blade receptacle (1) with black

lead and red plug (2) of the

diagnostic cable

Target value: < 10 ohms.

If the target values are not

attained

– Check contact between blade

receptacle of the switch shaft and

contact spring

2410RA233 TG

2410RA234 TG

– Check continuity between leads

and blade receptacles

– Blade receptacles must be

firmly connected to the leads; in

the event of contact problems,

the wiring harness must be

replaced, b 8.2.3, b 8.2.6

Check leads between solenoid

valve and diagnostic jack

– Connect the test lead, b 8.2.2

– Versions with manual fuel pump,

remove fuel pump and set it

aside, b 8.2.3

: Disconnect the plug (1) from the

solenoid valve (2) – the solenoid

valve must not be twisted; if

necessary, hold the solenoid

valve in place when

disconnecting the plug

: Measure the resistance between

red lead (1) at the plug of the

solenoid and black plug (2) of the

diagnostic cable

2410RA229 TG

2410RA235 TG

1 2

Target value: < 10 ohms

: Measure the resistance between

black lead (1) at the plug of the

solenoid and red plug (2) of the

diagnostic cable

Target value: < 10 ohms

If the target values are not

attained

– Check contact surfaces on plug

of the plug connection, as well as

checking electrical leads for

interruption, e. g., cable

breakage

– If the contact surfaces on the plug

are damaged in the plug

connection between wiring

harness and switchgear, the

wiring harness must be replaced,

b 7.7.2, if the contacts in the

jack are damaged, the

switchgear must be replaced,

b 8.4

– Reassemble remaining parts in

reverse order

2410RA236 TG

76 MS 241 C

8.3 Wiring harness

– The M-Tronic leads and the

ground wire are all combined into

one wiring harness; removal and

installation are described in the

chapter "Short-circuit wire",

b 7.7.2

8.4 Switchgear

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

– Check switchgear, b 8.2.5

– Remove choke rod, b 11.4

– Remove baffle, b 13.2

– Remove filter base, b 13.3

: Pull holder (1) of the switchgear

over the studs (arrows) and lay it

aside

2410RA239 TG

Versions with heating

: Remove blade receptacle (1)

: Remove heating element (2)

from the studs

Versions with manual fuel pump

: Disconnect the fuel hose (1)

: Push out the holder (1) with the

fuel pump on the air guide

shroud (2) and lay it on top of the

air guide shroud

2410RA240 TG

2410RA241 TG

2410RA242 TG

All versions

: Pull plug connector (1) out of the

carburetor support mount (arrow)

: Hold the jack (1), press the

tab (arrow) and pull out the

plug (2) – do not tug on the leads

2410RA243 TG

2410RA172 TG

2 1

77MS 241 C

The fuel hose does not have to be

removed from the carburetor

support.

: Carefully pull out the carburetor

with the fuel hose over the studs

and lay it aside – do not

overextend the fuel hose

: Turn the throttle shaft lever (1)

slightly in the direction of full-

throttle, then turn the starter

shaft (2) until the choke shutter is

closed

: Disconnect the plug (1) from the

solenoid valve (2) – the solenoid

valve must not be twisted; if

necessary, hold the solenoid

valve in place when

disconnecting the plug

2410RA244 TG2410RA245 TG

2410RA246 TG

: Pull the wiring harness (1) out of

the guide (arrow) and pull it out

between the special bolt (2) and

the starter shaft (3)

: Check lever on the starter

shaft (3), replace if necessary,

b 13.6.6

Installation

With a new switchgear, first the

leads must be inserted in the guides

of the switchgear.

Leads and plug connections must

not be damaged.

: Press red lead (1) and black

lead (2) completely into the

guides (arrows) of the

switchgear (3)

– see illustration

2410RA247 TG

2410RA248 TG

: Orient plug (1) so that the guide

pin (arrow) faces the carburetor

: Push the plug (1) into the jack of

the solenoid (2) as far as it will go

: Orient wiring harness (1) so that

the red lead runs underneath the

black lead

Choke shutter must be closed.

: Guide wiring harness (1)

between the special bolt (2) and

the starter shaft (3)

2410RA249 TG

2410RA250 TG

78 MS 241 C

: Position the wiring harness (1) so

that the protective tube (2) rests

against the beginning of the

guide

: Press the red and black leads

completely into the

guides (arrows)

Versions with heating

: Check the lead (1) of the

thermostatic switch, if necessary,

press it completely into the

guides (arrows) on the base of

the carburetor and route it behind

the pin (5)

Plug connectors (2) and (3) and the

generator lead (4) must be seated

completely in the guides.

2410RA251 TG

2410RA252 TG

2 3

Versions with manual fuel pump

: Check seat of the fuel return

line (1), if necessary. press it

completely into the

guides (arrows)

All versions

Washer (1) must be fitted.

Do not remove the fuel hose from

the carburetor support.

: Carefully push the carburetor (1)

with the fuel hose (2) over the

studs (arrows) – do not

overextend the fuel hose

2410RA253 TG

2410RA078 TG

2410RA254 TG

: Orient plug (1) and jack (2) that

the tab (3) lines up with the

opening (arrow) – do not twist the

leads

: Plug connector (1) into jack (2)

until the tab (3) clicks into place

: Press the plug connection (1)

into the mount (2) of the

carburetor support so that the

tab (arrow) engages and snaps

into place in the recess of the

plug connection

– Plug connection (1) must be

seated firmly in the mount (2)

– Push on the carburetor as far as

it will go – pay attention to cable

routing and make sure not to

pinch any leads

2410RA188 TG

1 2

2410RA256 TG

79MS 241 C

Versions with heating

: Press thermostatic switch

lead (1) completely into the

guide (arrow) of the air guide

shroud

– Lead (1) must form a loop at the

plug connection

: Slide the heating element (1)

over the studs so that the hole

engages the pin (2)

: Orient the crimped side of the

blade receptacle (3) so that it

faces the carburetor

: Push the blade receptacle (3)

completely onto the connector

tab (arrow)

2410RA257 TG

2410RA258 TG

Versions with manual fuel pump

: Push the holder (1) with the fuel

pump into the mount of the air

guide shroud (2) as far as it will

go; push new fuel hose (3) onto

the connectors (arrows)

: Fuel return line (4) must be

seated completely in the

guide (5); if necessary, press the

fuel return line (4) into the

guide (5) again

2410RA259 TG

All versions

: Push the holder (1) of the

switchgear over the studs so that

the tab rests against the

pin (arrow)

– Install filter base, b 13.3

– Reassemble remaining parts in

reverse order

2410RA260 TG

80 MS 241 C

8.5.1 Engine does not start

Can engine

be started?

– Set Master Control lever

to position }

Troubleshooting completed

– Check ignition (spark

plug, spark plug boot,

ignition spark), b 7.4

Ignition spark

present?

– Check start detection,

(microswitch, actuating

lever), b 8.2.5

– Examine switch gear,

clean or replace if

necessary, b 8.2.5

– Check start detection and

wiring harness electrically,

b 8.2.5, b 8.2.6

yes

Mechanically

OK?

Are target values

attained?, b 8.2.5

– Look for a fault in the fuel

path, check engine for

leaks, b 13.11, b 6.2

– Examine switch gear and/

or wiring harness, clean or

replace if necessary,

b 8.2.5, b 8.2.6

yes

Engine does not start

Is it possible to start

the engine?

yes

– Check solenoid valve,

b 8.2.4

Are target values

attained? b 8.2.4

– Replace carburetor,

b 13.5

yes

– Test ignition system

according to flow chart

"Ignition system

troubleshooting", b 7.8

yes

8.5 Troubleshooting, M-Tronic

81MS 241 C

8.5.2 Engine does not start in

position }

Is it possible to start

the engine?

Troubleshooting completed

– Check start detection

(microswitch actuation)

clean if necessary

– Examine switch gear,

clean or replace if

necessary, b 8.2.5, b 8.4

– Check start detection,

wiring harness and plug

connections,

b 8.2.5,b 8.2.3

yes

Mechanically

OK?

Are target values

attained?, b 8.2.5

– Look for a fault in the fuel

path (inlet needle, lever,

spring, membrane),

check engine for leaks,

b 13.11, b 6.2

– Examine switch gear and/

or wiring harness, clean or

replace if necessary,

b 8.2.5, b 8.2.3

yes

Engine does not start in

position } – engine floods.

Can the flooded engine be

started in position F?

yes

82 MS 241 C

8.5.3 Engine speed drops

under load

– low power

– Look for a fault in the fuel

path, check engine for

leaks,

b 13.11, b 6.2

– Examine air filter, clean or

replace if necessary, b 13.1

Troubleshooting completed

Machine OK?

yes

Engine speed drops under load –

low power

– Calibrate control unit,

b 8.1

83MS 241 C

8.5.4 Ignition – no ignition

spark

– Set Master Control lever

to position }

Troubleshooting

completed

– Check the flywheel,

(two pairs of poles?) b 7.6

Combination

OK?

– Check air gap between

control unit and flywheel,

b 7.3

Establish correct control unit/

flywheel combination

yes

Air gap

OK?

– Test ignition system

according to flow chart

"Ignition system

troubleshooting", b 7.8

– Set correct air gap, b 7.3

No ignition spark

yes

Can engine

be started?

84 MS 241 C

8.5.5 Engine stops suddenly

Machine

OK?

Troubleshooting

completed

– Check fuel path (fuel pick-up

body, tank vent, fuel hoses),

b 13.11

– Repair fuel

system

– Check plug connection on

control unit or between wiring

harness and switchgear

yes

Fuel path

OK?

Connection

and firm seat of the

plugs OK?

– Check plug connections,

replace wiring harness

and/or switching device, if

necessary b 8.2.3,

b 8.3, b 8.4

yes

Engine stops suddenly

yes

– Check start

detection (microswitch,

actuating lever), clean if

necessary

– Replace switchgear,

b 8.4

– Check start detection, wiring

harness and plug connections,

b 8.2.5, b 8.2.6

Mechanically

OK?

– Examine switch gear

and/or wiring harness,

clean or replace if

necessary, b 8.2.5,

b 8.2.6, b 8.3, b 8.4

yes

– Check solenoid valve,

b 8.2.4

Are target values

attained?, b 8.2.4

– Replace carburetor,

b 13.5

yes

– Check engine for leaks,

b 6.2

Are target values

attained?, b 8.2.5

85MS 241 C

8.5.6 Cut-off speed not

reached

– Check air filter and spark arrestor screen

(if present) in muffler, clean or replace if

necessary, b 13.1, b 6.1

– Check saw chain tension and chain

lubrication

–Calibrate control unit,

b 8.1

Maximum speed

greater than 13000

rpm?

Maximum speed less than

13000 rpm

– Look for a fault in the fuel

path, check engine for

leaks,

b 13.11, b 6.2

Troubleshooting

completed

yes

– Check plug connection on

control unit, b 8.2.3

Connection

and firm seat of the

plug

OK?

– Check plug, replace

insulating housing or

wiring harness if

necessary, b 7.3

yes

– Check start detection,

wiring harness and plug

connections, b 8.2.5

b 8.2.3

– Replace switchgear,

b 8.4

yes

Are target values

attained?, b 8.2.5

86 MS 241 C

9. Rewind starter

9.1 General

If the action of the starter rope

becomes very stiff and the rope

rewinds very slowly or not

completely, it may be assumed that

the starter mechanism is in order

but plugged with dirt. At very low

outside temperatures, the

lubricating oil on the rewind spring

may thicken and cause the spring

windings to stick together. This has

a detrimental effect on the function

of the starter mechanism.

To clean the rewind spring, it is

sufficient to apply a few drops of a

standard solvent-based degreasant

not containing any chlorinated or

halogenated hydrocarbons to the

rewind spring.

Carefully pull out the starter rope

several times and allow it to rewind

until its normal smooth action is

restored.

Before installing, lubricate the

rewind spring and starter post with

STIHL special lubricant, b 16.

If clogged with dirt or pitch, the

entire starter mechanism, including

the rewind spring, must be removed

and disassembled. Take particular

care when removing the rewind

spring.

– Clean all components

Versions with ErgoStart

– Relieve the tension of the rewind

spring, b 9.4

9.2 Fan housing

– Remove shroud, b 6.4

: Remove screw (1) with sleeve

and screws (arrows)

– Lift hand guard slightly and

remove fan housing

: Push out segment (1) on the

pegs (2) on the opposite side

through the holes with drift

– Examine fan housing and

segment, replace if necessary.

2310RA201 TG

2310RA202 TG

Installation

: First insert and position

segment (1) in the slit (arrow) on

the fan housing

: Press segment (1) as far as it will

go into the pegs (2)

– Lift hand guard slightly and

position fan housing

: Insert and tighten screw (1) with

sleeve and screws (arrows)

– Reassemble remaining parts in

reverse order

2310RA203 TG

2310RA202 TG

2310RA201 TG

87MS 241 C

9.3 Pawls

– Remove fan housing, b 9.2

– Relieve the tension of the rewind

spring, b 9.5

: Carefully ease the spring (1) off

the starter post

– Remove pawl

Installation

– Press new pawl into hole (arrow)

and grease the peg (1), b 16

2310RA204 TG

2310RA205 TG

: Position the spring (1) so that the

loop of the spring encloses the

peg of the pawl and the curved

part of the spring (arrow) is

located in the groove in the

starter post

: Then slide the straight part of the

spring over the starter post until it

engages in the groove

The guide loop of the spring must

run along the pawl (arrow).

Checking correct functioning

– Pull starter rope, the rope rotor

turns, and the peg at the pawl

moves in the direction of the

anchor loop – the pawl moves

outward

– Reassemble remaining parts in

reverse order

2310RA206 TG

2310RA207 TG

Versions with ErgoStart

– Remove ErgoStart, b 9.4

Two pawls are installed in the

version with ErgoStart. Removal is

the same as with the standard

version.

– Grease the mounts of the new

pawls, b 16

– Insert the new pawls and oil the

pegs of the pawls with resin-free

lubricating oil, b 16

Installation

Washer (1) must be fitted.

: Position spring (2) so that its

anchor loops engage the pegs of

the pawls and the curved part of

the spring (arrow) is located in

the groove of the rope rotor post

: Then slide the straight part (3) of

the spring over the starter post

until it engages in the groove

– Reassemble remaining parts in

reverse order

2310RA208 TG

88 MS 241 C

9.4 ErgoStart

The spring may still have spring

tension stored in it, thus release the

spring tension before any assembly

procedure:

– Pull out the starter until the

engine turns – the preloaded

spring is relaxed

– Remove fan housing and, if

necessary, segment, b 9.2

: Remove the circlip (1)

: Remove washer (2) and

carrier (3)

: Remove spring housing (4)

: Push out circlips (arrows)

: Pull out pawls (1) and remove

torsion springs

– Clean the mounts of the

pawls (1), b 16

2310RA209 TG

3 2 1

2710RA165 TG

Installation

: Install torsion springs in pawls (1)

– observe installation

position (arrows)

: Push pawls (1) onto the posts (2)

on the flywheel, in the process

pretensioning the torsion springs

and positioning them on the

support ribs (arrow)

: Push on the pawls (1) so that

they can move towards the

middle of the flywheel as far as

they will go

: Push circlips (2) into place

533RA198 TG

5902RA581 TG

2710RA274 TG

Checking correct functioning

The pawls must move freely and

rest against the stop due to the

spring force.

: Push spring housing (1) over the

rope rotor post into the pawls of

the rope rotor (2) – the pawls

must engage in the spring

housing

: Insert the carrier (1) in the spring

housing so that the

recess (arrow) engages the

anchor loop (2) of the rewind

spring

: Fit washer (3)

: Fit the circlip (4)

– Do not overextend circlip

– Reassemble remaining parts in

reverse order

2310RA210 TG

2310RA211 TG

2 1 3 4

89MS 241 C

9.5 Rope rotor

Relieve tension of rewind spring

The system will not be under

tension if the starter rope or rewind

spring is broken.

– Remove fan housing and

segment, b 9.2

Versions with ErgoStart

– Remove ErgoStart, b 9.4

All versions

: Pull out the starter rope (1)

about 5 cm, then hold the rope

rotor (2) steady

– Still holding the rope rotor steady,

take three full turns off the rope

rotor

– Pull out the rope with the starter

grip and carefully release the

rope rotor

– Remove the starter rope; remove

any remaining scraps of rope,

b 9.6

– Remove spring and pawl or

pawls, b 9.3

2310RA212 TG

: Remove the washer (1)

The rewind spring must be relieved.

: Carefully pull off the rope rotor (2)

–The rewind spring may pop out

– Examine the rope rotor, replace if

necessary.

– Coat the hole in the rope rotor

with STIHL special lubricant,

b 16

Installation

: Fit the rotor on the starter post so

that the inner loop of the

spring (arrow) enters the

recess (1)

The recess in the hub of the rope

rotor acts as carrier for the anchor

loop.

– Fit the washer.

2310RA213 TG

2310RA214 TG

– Install pawl or pawls and spring,

b 9.3

– Install starter rope, b 9.6

– Tension the rewind spring, b 9.7

– Grease the pegs of the pawl or

pawls, b 16

– Reassemble remaining parts in

reverse order

9.6 Starter rope / starter grip

– Remove fan housing and

segment, b 9.2

Versions with ErgoStart

– Remove ErgoStart, b 9.4

All versions

– Relieve the tension of the rewind

spring, b 9.5

The rewind spring will not be under

tension if the starter rope is broken.

– Remove any remaining rope from

the rope rotor if necessary

The starter rope must not be

shortened.

90 MS 241 C

: Push starter rope (1) out a short

distance and undo the knot

– Pull starter rope out of rope rotor

and fan housing.

: Tie one of the two special knots

shown above at the end of the

rope in the starter grip.

: Thread the new starter rope into

the starter grip from above

2310RA215 TG

165RA227 TG

4903RA131 TG

Pull the rope through the grip until

the knot at the end of the rope is in

the recess (arrow)

: Then thread the rope (1) through

the opening (arrow)

: Thread starter rope (1) into rope

rotor

– Secure the rope (1) with a simple

overhand knot

4903RA132 TG2310RA216 TG

2310RA217 TG

: Pull starter rope (1) into rotor until

the knot rests in the

recess (arrow) of the rope rotor

– Tension the rewind spring, b 9.7

– Reassemble remaining parts in

reverse order

9.7 Tensioning the rewind

spring

– Remove fan housing and

segment, b 9.2

: Pull out part of the starter rope (1)

: Turn starter rope (1) with rope

rotor (2) six times clockwise

The rewind spring is now tensioned.

Hold the tensioned rope rotor firmly,

as the rewind spring will be

damaged if it jumps back suddenly.

2310RA218 TG

2310RA219 TG

91MS 241 C

: Hold the rope rotor (1) steady

: Pull out the twisted starter

rope (2) with the starter grip and

straighten it out

: Hold the starter grip firmly to

keep the rope (1) tensioned

: Let go of the rope rotor (2) and let

the starter rope rewind slowly

The rewind spring is correctly

tensioned when the starter grip (1)

sits firmly in the rope guide

bushing (arrow) without drooping to

one side. If this is not the case, the

rewind spring must be tensioned by

one additional turn.

2310RA220 TG

2310RA221 TG

2310RA222 TG

When the starter rope is fully

extended, it must still be possible to

rotate the rope rotor at least

another turn before the maximum

spring tension is reached. If not, the

spring tension must be reduced,

otherwise it will break.

Reduce spring tension

Pull the rope out, hold the rope rotor

steady and take off one turn of the

rope.

– Reassemble remaining parts in

reverse order

9.8 Replacing the rewind

Spring

– Troubleshooting, b 3.4

The replacement spring is supplied

ready for installation and secured in

a spring housing.

– Wear face shield and protective

gloves

– risk of injury

– Remove fan housing and

segment, b 9.2

– Relieve the rewind spring if

necessary and remove the rope

rotor, b 9.5

– Remove any fragments of the old

spring

If the rewind spring no longer

produces sufficient tension, it must

be replaced.

A worn rewind spring may still be

under tension while installed.

– Lay a blanket over the assembly

area and remove the rewind

spring from the fan housing

Install new rewind spring

– Lubricate replacement spring

with frame with a few drops of

STIHL special lubricant before

installing it, b 16

: Position replacement spring with

frame in the fan housing so that

the outer anchor loop (1) is

positioned over the mount for the

loop (2) and aligns with the

mount (arrow)

: Starting at the outer anchor loop,

push the new rewind spring

through the openings (arrows)

into the mount of the fan housing

– in the process, the frame is

removed

2310RA224 TG

2310RA226 TG

92 MS 241 C

: Press the frame (1) against the

rewind spring and turn it slightly

clockwise until the rewind spring

is completely seated

The rewind spring may pop out.

– Carefully remove the frame and

keep it

– The frame is reused as an

installation tool for installing

rewind springs that have popped

out

Make certain that the

rewind spring (1) is inserted

completely and the outer anchor

loop is seated in the anchor loop

mount (arrow), if necessary, press

the rewind spring completely into

the mount in the fan housing.

– Secure the rewind spring so that

it cannot pop out

– Install the rope rotor, b 9.5

– Reassemble remaining parts in

reverse order

2310RA227 TG

2310RA228 TG

Reinstalling a rewind spring that

has popped out

If the rewind spring pops out during

installation, fit it in the fan housing

as follows:

– Arrange the rewind spring (1) as

shown in the illustration

: Insert outer anchor loop in the

recess (arrow) of the fan housing

: Fit the rewind spring (1) in the

spring housing in a circular

fashion, working in clockwise

direction while holding the

inserted turns of the spring in

place

The further course of action is the

same as for "Installing a new rewind

spring".

2310RA230 TG

2310RA231 TG

Versions with ErgoStart

Install new rewind spring

: Check washer (1) and replace if

necessary

– Lubricate replacement spring

with frame with a few drops of

STIHL special lubricant before

installing it, b 16

Position replacement spring with

frame in the fan housing so that the

outer anchor loop (1) is positioned

over the mount for the loop (2) and

aligns with the mount (arrow)

The further course of action is the

same as for "Installing a new rewind

spring" in versions without

ErgoStart.

2310RA223 TG

2310RA225 TG

93MS 241 C

Make certain that the rewind

spring (1) is inserted completely

and the outer anchor loop is seated

in the anchor loop mount (arrow), if

necessary, press the rewind spring

completely into the mount in the fan

housing.

– Secure the rewind spring so that

it cannot pop out

– Install the rope rotor, b 9.5

– Reassemble remaining parts in

reverse order

2310RA229 TG

Reinserting a popped out rewind

spring into the frame

In versions with ErgoStart, the

rewind spring mount sits lower, thus

the rewind spring can only be

inserted directly into the fan housing

premounted in a frame.

If the rewind spring pops out during

installation, fit it in the frame as

follows:

: Insert anchor loop in the

recess (arrow) of the frame

: Fit the rewind spring (1) in the

frame in a circular fashion,

working in counterclockwise

direction while holding the

inserted turns of the spring in

place

The further course of action is the

same as for "Installing a new rewind

spring" in versions with ErgoStart.

5902RA608 TG

94 MS 241 C

10. Maintaining the antivibration elements

The front handle / tank housing and

crankcase are connected by

vibration-damping springs, rubber

buffers and stop buffers.

Damaged springs rubber buffers

and stop buffers must always be

replaced.

10.1 Antivibration element on

oil tank

The antivibration elements are

located in the area of the oil tank

and are fastened to the bottom of

the machine.

– Remove the front handle,

b 10.4, versions with heating,

b 10.4.1

: Remove screw (1)

: Remove the chain catcher (2)

– Remove the tank housing,

b 13.11.5

2410RA300 TG

: Twist out spring (1) with bearing

plug (2)

– Inspect spring with plug, replace

if necessary

Installation

Bearing plug (1) must be twisted

into the spring (2) as far as it will go.

: Twist spring (2) with bearing

plug (1) into the mount (arrow) as

far as it will go

– Install the tank housing,

b 13.11.5

2310RA233 TG

2310RA234 TG

: Push the chain catcher (3) into

the mount so that it engages

under the bumper strip (2)

: Screw in the screw (1) and

tighten it

– Reassemble remaining parts in

reverse order

10.2 Antivibration element on

fuel tank

: Remove screw (1)

2410RA301 TG

2410RA302 TG

95MS 241 C

Versions with heating

: Remove screw (1) on front

handle

All versions

: Remove screws (1)

: Push tank housing (2) down

slightly and hold it there

: Push front handle out of the

mount (arrow) on the peg (1)

– Do not remove screws on front

handle

2410RA303 TG

2310RA236 TG

2410RA304 TG

: Remove cover (1)

: Push the antivibration

element (1) slightly upward and

lift it out of the guide (arrow)

: Remove antiivibration

element (1) between crankcase

and tank housing

– Inspect spring and plug, replace if

necessary

2310RA237 TG

2310RA238 TG

Installation

– Push tank housing down slightly

and hold it there

: Orient antivibration element so

that the tab (1) faces the

crankcase and push it bearing

plug (2) first between crankcase

and tank housing

: Push bearing plug (2) through

the opening

: Push the bearing plug (3) into the

mount (arrow)

: Position cover (1) so that it

engages the peg (arrow)

2310RA239 TG

2310RA240 TG

96 MS 241 C

: Push tank housing upward until

the peg (1) of the front

handle engages in the

mount (arrow)

: Raise tank housing (1)

: Orient bearing plugs (2) and

cover (3) so that the holes align

with the hole on the tank housing

: Screw in and tighten

screws (5) and (4)

2410RA304 TG

2310RA241 TG

: Position bearing stopper (1)

: Coat screw (2) with Loctite,

screw in and tighten, b 16

Versions with heating

: Position bearing plug (1) and

insert and tighten screw (2)

– Reassemble remaining parts in

reverse order

2410RA306 TG

2410RA307 TG

10.3 Antivibration element on

front handle

The antivibration element is

between front handle and cylinder.

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

: Remove screw (1)

– Remove the front handle,

b 10.4

: Twist out bearing plug (1) and

unhook retainer (arrow)

: Twist out spring (2) and push

retainer (arrow) out of front

handle

– Inspect spring and bearing plug

and retain, replace if necessary

2410RA302 TG

2310RA243 TG

97MS 241 C

Installation

: Push retainer (1) with the small

nipple into the hole in the front

handle (2)

: Twist spring (3) onto the

peg (arrow) as far as it will go

: Hook retainer (arrow) onto

bearing plug (1)

: Push bearing plug (1) into the

spring as far as it will go

– Install the front handle, b 10.4

2310RA244 TG

2310RA245 TG

: Position bearing plug (1) against

cylinder

: Coat screw (2) with Loctite,

screw in and tighten, b 16

– Reassemble remaining parts in

reverse order

10.3.1 Antivibration element on

handlebar, version with

heating

: Remove screws (1) and (2)

: Remove the antivibration

element (3) completely

2410RA306 TG

2410RA308 TG

: Twist out bearing plug (1) and

unhook retainer (arrow)

: Twist out spring (2) and pull out

retainer (arrow)

Installation

: Insert retainer (1) with the nipple

in the holder (2)

: Twist spring (2) onto the peg

: Hook retainer (arrow) onto

bearing plug (1)

: Twist bearing plug (1) into the

spring (2) as far as it will go

0001RA219 TG

5902RA246 TG

0001RA219 TG

98 MS 241 C

: Position antivibration element (1)

against front handle and cylinder

: Screw in the screw (2) and

tighten it

: Coat screw (3) with Loctite,

screw in and tighten, b 16

– Reassemble remaining parts in

reverse order

10.3.2 Stop buffer

The stop buffers are installed

between crankcase and tank

housing on the ignition and clutch

side.

– Remove the tank housing,

b 13.11.5

: Pry out stop buffers (1) on the

ignition and clutch sides

2410RA309 TG

2410RA310 TG

– Replace stop buffer

Installation

– Orient the stop buffer (1) on both

sides – the conical pegs (arrow)

facing the crankcase

– To simplify installation, coat the

conical pegs with STIHL press

fluid, b 16

: Press the stop buffers (1) with the

pegs on the inside of the

crankcase completely into holes

– to simplify assembly, twist the

stop buffers while pressing them

The conical pegs must enclose the

holes completely.

– Reassemble remaining parts in

reverse order

2410RA311 TG

2410RA312 TG

10.3.3 Filter base buffers

– Remove filter base, b 13.3

: Remove screw (1)

: Push tank housing (2) down

slightly and hold it there

: Press out the buffers (1) on the

underside (arrows)

– Check buffers (1) and replace if

necessary

2310RA249 TG

2410RA313 TG

1 1

99MS 241 C

Installation

: Orient buffers (1)

– conical pegs facing the

holes (arrows)

– To simplify installation, coat the

conical pegs with STIHL press

fluid, b 16

: Press the buffers (1) with the

conical pegs completely into the

holes (arrows) –to simplify

assembly, twist the buffers while

pressing them in

The conical pegs (arrows) must

enclose the holes completely on the

reverse.

2410RA314 TG

1 1

2410RA315 TG

: Push tank housing (1) upward

and hold it there

: Screw in the screw (2) and

tighten it

– Reassemble remaining parts in

reverse order

10.4 Front handle

– Remove shroud, b 6.4

: Remove screw (1)

– Take out screws

2310RA253 TG

2410RA302 TG

2410RA315 TG

: Lift front handle (1) slightly at the

side and remove it from the

guide (arrow).

: Remove screws (1) on the

underside of the machine and lift

front handle (2) out of the

mount (arrow)

: Remove front handle (1) from the

lower guide

– Remove and examine front

handle (1), replace if necessary

– Examine the antivibration spring

and replace if necessary, b 10.3

2310RA157 TG

1 1 2

0001RA232 TG

100 MS 241 C

Installation

– Position front handle

: Lift front handle (1) with the

peg (2) facing forward into the

recess (arrow) until it is seated in

the mount of the tank housing

– Insert and tighten down

the screws

: Lift the front handle (1) somewhat

at the side and place it in the

guide (arrow) so that the peg (2)

engages in the mount of the

crankcase

– Insert and tighten down the

screws

2310RA158 TG

2410RA317 TG

: Position bearing plug (1) of the

antivibration spring against

cylinder

: Coat screw (2) with Loctite,

screw in and tighten, b 16

– Reassemble remaining parts in

reverse order

10.4.1 Handlebar with heating

As the front handle is heated in

these machines, the wiring must

also be disconnected for

installation.

– Troubleshooting, b 14.7.1

– Remove shroud, b 6.4

– Remove handle molding, trigger

interlock and throttle trigger,

b 11.2

: Pull throttle rod (1) out of the

mount (arrow) and unhook it from

the throttle trigger (2)

2410RA306 TG

2310RA167 TG

: Remove screw (1) on front

handle

: Remove screws (1) on front

handle (2) on the underside of

the machine

: Remove screw (1)

2410RA303 TG

2310RA157 TG

1 1 2

2410RA557 TG

101MS 241 C

: Press pegs (1) out of the

mount (arrow) and lower front

handle (2) with tank housing

: Unscrew screw (1) and remove

cover (2)

: Pull plug connections (1), (2)

and (3) with insulating tubes out

of the guides

2410RA319 TG

2410RA321 TG

2410RA322 TG

: Push insulating tube (1) toward

the wiring harness and push

insulating tube (2) toward the

front handle heating element

Do not disconnect plug

connection (3).

: Disconnect plug connections (4)

and (5)

: Remove screws (1)

: Lift front handle (1) at the side

and remove the cover (2) from

the mount

2410RA323 TG

1 4

2 5

2410RA320 TG

2410RA324 TG

: Remove front handle (1) from the

lower guide

– Remove front handle

: Unscrew screw (1) while pushing

down the plastic sleeve (2)

– Remove plastic sleeve

: Remove the handle insert (1)

– Examine the front handle

heating, replace front handle if

necessary

b 14.6

0001RA240 TG

2410RA325 TG

2410RA326 TG

102 MS 241 C

Installation

– Press the plug connection

together completely, b 1

: Press in the handle insert (1) as

far as it will go

: Screw in the screw (1) and

tighten it

: Push on plastic sleeve (2) until it

snaps into place

2410RA327 TG

2410RA328 TG

The leads on the front handle are of

different lengths; during assembly,

take care that the short lead (1) is

connected to the lead to the heating

switch and the long lead (2) is

connected to the lead to the handle

heating element.

– Position front handle

: Lift front handle (1) with the

peg (2) facing forward into the

recess (arrow) until it is seated in

the mount of the tank housing

– Insert screws – do not tighten

2410RA329 TG

2310RA158 TG

Do not pinch the leads and plugs.

: Lift front handle (1) slightly and

push the cover (2) into the mount

: Push the front handle (1) into the

mount (arrow)

: Orient the leads of the front

handle in the guide (arrow) so

that the long lead (1) runs

underneath the short lead (2)

The wiring harness and the

connecting leads must be located

underneath the throttle rod (3).

2410RA330 TG

2410RA335 TG

103MS 241 C

: Insert and tighten screws (1) –

lines must be seated in the

guide (arrow)

– Tighten screws of the front

handle on the underside of the

machine

: Push insulating tube (1) onto

lead of the heating switch

: Push connector (2) with short

lead completely into the terminal

socket (3)

– Push insulating tube entirely over

the plug connection

2410RA332 TG

2410RA333 TG

1 3 2

: Push insulating tube (1) onto

thick lead of the handle heating

: Push connector (2) with long lead

completely into the terminal

socket (3)

– Push insulating tube entirely over

the plug connection

– Lift tank housing slightly

Plug connection with longer lead of

the front handle.

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

2410RA334 TG

1 3 2

2410RA336 TG

Plug connection with shorter lead of

the front handle.

: Press insulating tube (1) with

plug connection as far as it will go

into the guide (arrow)

– Lift the tank housing again and

hold it there

: Press insulating tube (1) with

plug connection as far as it will go

into the guide (arrow)

2410RA337 TG

2410RA338 TG

104 MS 241 C

: Run the thin lead (1) with a

loop (2) around the rib and press

it into the guide (arrow) as far as

it will go

: Orient cover (1) so that the

pegs (2) engage the holes and

the tab (3) engages the

fin (arrows)

– Replace cover, insert and tighten

screw

– Ensure that wires are not

pinched

2410RA339 TG

2410RA340 TG

The leads of the handle heating

element must be seated completely

in the guide (arrow).

– Install throttle trigger, b 11.2

: Hook throttle rod (1) onto throttle

trigger (2) and press it into the

guide (arrow)

– Install trigger interlock and

handle molding, b 11.2

2410RA341 TG2310RA167 TG

: Push tank housing (1) upward

and hold it there

: Screw in the screw (2) and

tighten it

– Reassemble remaining parts in

reverse order

2310RA253 TG

105MS 241 C

11. Actuating levers

11.1 Master Control lever

The positions of the Master Control

lever are described in the

Instruction Manual.

11.1.1 Removal and installation

– Remove the air filter, b 13.1

– Remove choke rod, b 11.4

– Remove the filter base from the

studs, b 13.1

– Remove contact spring, b 7.7.4

: Turn the switch shaft (1)

counterclockwise as far as it will

go and pull it of off the shaft (2) of

the filter base

– Disconnect ground wire at the

switch shaft, b 7.7

: Take out and examine the switch

shaft (1), replace if necessary

2310RA160 TG

2310RA161 TG

– Examine the filter base, replace if

necessary

Installation

– Position filter base in the

carburetor space

: Position switch shaft (1) in

carburetor space

– Install ground wire on the switch

shaft, b 7.7

: Orient the switch shaft (1) so that

the inserted ground wire faces

the filter base and the

opening (arrow) lines up with the

rib (2)

2310RA162 TG

2410RA343 TG

: Press the switch shaft (1) onto

the post (2) of the filter base as

far as it will go

– Install contact spring, b 7.7.4

: Check correct functioning

– Blade receptacle of the ground

wire must touch the contact

spring (arrow) in position "

– Reassemble remaining parts in

reverse order

2310RA164 TG

2310RA155 TG

106 MS 241 C

11.2 Throttle trigger / throttle

trigger interlock

: To disassemble the handle

molding. press the pegs (1) on

the underside apart and through

the rear hand guard

: Remove handle molding (1)

The trigger interlock (arrow) may

pop out.

: Pull the trigger interlock (1) out of

the bearing points (arrows)

5902RA307 TG

2310RA165 TG

2310RA166 TG

: Pull throttle rod (1) out of the

mount (arrow) and unhook it from

the throttle trigger (2)

: Push out pin (1) with drift (2)

: Remove throttle trigger (3) with

torsion spring (4)

– Examine trigger interlock, throttle

trigger and torsion springs,

replace if necessary

Installation

: Hook the torsion spring (1) into

the throttle trigger (2)

– Note the installed

position (arrow)

2310RA167 TG

2310RA168 TG

2310RA169 TG

: Insert throttle trigger (1) into the

handle so that the tab (arrow) is

inside the handle and the holes

on the throttle trigger and handle

align

: Center the throttle trigger (1) with

punch (2)

In version with heating, the

connecting leads must be routed

entirely in the guide and must not

protrude

– Risk of leads becoming pinched,

b 14.9.

: Drive in the pin (3) until it is

equidistant on both sides

: Hook the throttle rod (1) onto the

throttle trigger (2) and hook it into

the guide (arrow)

Make certain that the torsion spring

is hooked entirely into the throttle

trigger.

2310RA170 TG

2310RA171 TG

107MS 241 C

: Press end (1) of the torsion

spring toward the handle

: Press the trigger interlock (2) into

the bearing points (arrow)

: Hook the torsion spring (1) onto

the trigger interlock (arrow)

The trigger interlock may pop out.

: Hook handle molding (1) with the

tabs (2) into the openings (arrow)

– Fit handle molding (1) until it

snaps into place

2310RA172 TG

2310RA173 TG

2310RA174 TG

1 2

– Check correct functioning

– Reassemble remaining parts in

reverse order

11.3 Throttle trigger / throttle

trigger interlock /

QuickStop Super

After each removal, coat sliding and

bearing points with grease.

: To disassemble the handle

molding. press the pegs (1) on

the underside apart and through

the rear hand guard

: Remove handle molding (1)

5902RA307 TG

2310RA175 TG

: Pull throttle rod (1) out of the

mount (arrow) and unhook it from

the throttle trigger (2)

: Push out pin (1) with drift (2)

: Remove throttle trigger (1) with

torsion spring (2)

– Check rotor on throttle trigger to

ensure that it can be rotated,

replace throttle trigger if

necessary

– Examine the torsion spring and

replace it if necessary

2310RA176 TG

2310RA177 TG

2310RA178 TG

108 MS 241 C

Installation

: Hook the torsion spring (1) into

the throttle trigger (2)

– Note the installed

position (arrow)

: Insert throttle trigger (1) in the

handle so that the angled end of

the torsion spring engages in the

mount (arrow) and the holes on

the throttle trigger and handle

align

The brake cable (1) must lie

completely in the guide (arrows)

and be underneath the drift – do not

damage the brake cable.

2310RA179 TG

2310RA180 TG

2310RA181 TG

: Center the throttle trigger (1) with

punch (2)

: Drive in the pin (3) until it is

equidistant on both sides

: Hook the throttle rod (1) onto the

throttle trigger (2) and hook it into

the guide (arrow)

– Grease rotor on throttle trigger,

b 16

: Hook handle molding (1) with the

tabs (2) into the openings (arrow)

– Press trigger interlock

downwards

2310RA182 TG

2310RA183 TG

2310RA174 TG

1 2

– Carefully fit handle molding (1)

until it snaps into place

– Check correct functioning

– Reassemble remaining parts in

reverse order

11.3.1 Trigger switch

QuickStop Super

After each removal, coat sliding and

bearing points with grease.

– Remove handle molding, b 11.3

: Push out pin (arrow) with drift (1)

: Partly remove switch lever (1)

and turn by approx. 90°, then pull

off brake cable (2)

– Examine switch lever, replace if

necessary

2310RA184 TG

2310RA185 TG

109MS 241 C

Installation

: Hook brake cable (1) into

hole (arrow) in switch lever

: Turn switch lever (2) until it faces

upwards

: Center the throttle trigger (1) with

punch (2)

: Drive in the pin (3) until it is

equidistant on both sides

– Reassemble remaining parts in

reverse order

– Check function of the switch lever

by actuating the trigger interlock

2310RA186 TG

2310RA187 TG

11.3.2 Trigger interlock

QuickStop Super

After each removal, coat sliding and

bearing points with grease.

– Remove handle molding, b 11.3

: Push out pin (arrow) with drift (1)

– Remove trigger interlock

: Drive out bushing (1)

: Remove torsion spring (2)

– Examine trigger interlock, throttle

trigger and bushing, replace if

necessary

2310RA188 TG

2310RA189 TG

Installation

: Align torsion spring (1) and insert

in trigger interlock

: Slide bushing (2) into

hole (arrow) – torsion spring is

secured

Torsion spring (arrow) must rest

against the tank housing.

: Center trigger interlock (1) with

drift (2)

: Drive in the pin (3) until it is

equidistant on both sides

– Reassemble remaining parts in

reverse order

– Check correct functioning

2310RA190 TG

2310RA191 TG

110 MS 241 C

11.4 Choke rod

– Remove the air filter, b 13.1

: Move switch shaft (1) to position

F" and pry out choke rod (2) at

the mount (arrow)

: Unhook the choke rod (2) from

the lever (3)

– Examine choke rod and replace it

if necessary

Installation

: Hook choke rod (1) into

hole (arrow) in the starter

shaft (2)

2410RA344 TG

2410RA331 TG

: Insert choke rod (1) in

guide (arrow)

: Move switch shaft (2) to position

F" and hold it there, then press

choke rod (1) completely into the

mount (arrow)

– Check correct functioning

The choke rod must be completely

snapped into place.

– Reassemble remaining parts in

reverse order

11.5 Throttle rod

– Remove handle molding and

trigger interlock, b 11.2,

QuickStop Super, b 11.3

– Remove choke rod, b 11.4

– Remove baffle, b 13.2

– Remove filter base and set it

aside, b 13.3

– Carefully pull out the carburetor

over the studs and lay it aside

– Do not overextend fuel hose,

b 8.4

2410RA345 TG

: Pry out throttle rod (1) at the

carburetor support (2)

: Guide throttle rod (1) through the

opening (arrow) in the direction

of the control handle and remove

– Examine the throttle rod and

replace it if necessary

Installation

: Guide throttle rod (1) between

tank housing and crankcase

through the opening (arrow) in

the direction of the carburetor

support

2310RA293 TG

2310RA294 TG

2310RA295 TG

111MS 241 C

: Press the throttle rod (1) into the

guide (2) on the carburetor

support until it snaps into place

– Install handle molding and trigger

interlock, b 11.2, QuickStop

Super, b 11.3

– Push carburetor with attached

fuel hose onto the studs, b 8.4

– Install filter base, b 13.3

– Check correct functioning

– when the throttle trigger is

actuated, the throttle trigger must

move upwards at the carburetor

– Reassemble remaining parts in

reverse order

2310RA296 TG

112 MS 241 C

12. Chain lubrication

12.1 Pickup body

Impurities gradually clog the fine

pores of the filter with minute

particles of dirt. This prevents the oil

pump from supplying sufficient oil to

the bar and chain. Always check the

oil tank and pick-up body first if

problems develop in the oil supply.

– Troubleshooting, b 3.3

– Unscrew oil tank cap and drain oil

tank

– Collect oil in a clean container,

b 1

– Clean the oil tank if necessary,

b 16

: Pull pick-up body (1) out of oil

tank with assembly hook (2)

5910 893 8800

Take care not to overextend the

suction hose.

– Pull off pickup body (1) and

examine it, replace if necessary

– Reassemble parts in reverse

order

219RA457 TG

12.2 Oil suction hose

– Unscrew oil tank cap and drain oil

tank, b 1

– Remove the clutch, b 4.2

– Remove brake band, b 5.2

– Remove oil pump, b 12.3

: Pry out oil suction hose (1) and

pull it out with pickup body

– Examine oil suction hose and

pick-up body, replace if

necessary

– Fit the pickup body, b 12.1

Installation

– Coat groove of oil suction hose

with STIHL press fluid, b 16

: Push oil suction hose (1) through

opening in housing with the pick-

up body first

2410RA346 TG

2410RA347 TG

: Orient oil suction hose (1) so that

the straight sides (arrows) rest

against the crankcase

: Push in oil suction hose (1) until

the groove is completely flush

with the hole in the crankcase

– Check position of pick-up body,

clear it with the aid of assembly

hook 5910 893 8800 if necessary

– Install oil pump, b 12.3

– Reassemble remaining parts in

reverse order

12.3 Oil pump

– Troubleshooting, b 3.3

– Remove the clutch, b 4.2

– Remove brake band, b 5.2

: Remove the washer (1)

TOP

2410RA348 TG

113MS 241 C

: Pull worm (1) with spring (2) out

of oil pump

– Inspect spring and worm, replace

if necessary

: Unscrew screw (1) and remove

cover (2)

: Remove screws (1)

: Pull oil pump (2) out of the oil

suction hose and remove it

2410RA349 TG

2410RA350 TG

2410RA351 TG

: Remove sealing ring (1)

– Examine oil pump, replace if

necessary

Installation

: Push new sealing ring (1) into the

opening (arrow)

: Orient oil pump (1) so that the

connector (2) engages in the oil

suction hose (3) and the

connector (4) slides into the

sealing ring (5)

– Coat connectors and sealing ring

with STIHL press fluid, b 16

2410RA352 TG

2410RA353 TG

2410RA354 TG

: Push in oil pump (1) as far as it

will go

: Screw in screws (2)

and tighten them

– Push the worm home until it

makes contact

: Slide on the washer (1)

It has been fitted correctly when the

word "TOP" (arrow) is visible.

– Reassemble remaining parts in

reverse order

2410RA355 TG

TOP

2410RA356 TG

114 MS 241 C

12.4 Valve

A valve is installed in the tank wall to

keep internal tank pressure equal to

atmospheric pressure. The valve

must be replaced if faulty.

– Unscrew oil tank cap and drain oil

tank, b 1

: From the outside, carefully drive

the valve out of the case in the

direction of the inside of the tank

with a Ø 6 mm drift

: Remove old valve (1) from oil

tank

2410RA342 TG

219RA476 TG

Installation

Ensure that the parts are installed

correctly.

: Insert valve (1) into hole (arrow)

in crankcase

– Carefully drive valve into hole in

engine housing from the outside

with a Ø 6 mm drift – observe the

insertion depth

: Drive new valve into the hole

a=1mm +/- 0.1

– Reassemble remaining parts in

reverse order

2410RA318 TG

219RA479 TG

115MS 241 C

13. Fuel system

13.1 Air filter

Dirty air filters reduce engine power,

increase fuel consumption and

make starting more difficult. The air

filter should be checked when there

is a noticeable loss of engine power.

– Refer also to troubleshooting,

b 3.6, b 3.7

– Remove shroud, b 6.4

: Turn the air filter (1)

counterclockwise and remove it

– Examine air filter, clean or

replace if necessary

– see Instruction Manual

– Reassemble parts in reverse

order

2410RA255 TG

13.2 Baffle

– Remove the air filter, b 13.1

: Unscrew the nuts (arrows)

: Remove baffle (1)

– Examine baffle, replace if

necessary.

– Reassemble parts in reverse

order

13.3 Filter base

– Remove the air filter, b 13.1

– Remove choke rod, b 11.4

– Remove baffle, b 13.2

Versions with heating

: Remove lead (1) from cable

guide (arrow)

2410RA263 TG

2410RA169 TG

: Push buffer (1) out from under

the pin of the filter base (2)

: Remove filter base (1) from the

studs (arrows)

: Pull the filter base (1) out of the

buffer (2)

2410RA237 TG

2410RA264 TG

2410RA238 TG

116 MS 241 C

: Remove short circuit wire (1) and

contact spring (2) from the

guides (arrows)

– Remove contact spring, b 7.7.4

– Remove switch shaft, b 11.1

– Remove filter base

: Check buffer (1), replace if

necessary, b 10.3.3

2410RA265 TG

2410RA266 TG

1 1

Installation

– Position filter base in the

carburetor space

– Install switch shaft, b 11.1

– Install contact spring, b 7.7.4

– Use STIHL press fluid to improve

assembly, b 16

: Push the pin (1) of the filter

base (2) into the hole in the

ignition side buffer (3) as far as it

will go

: Orient the filter base (1) so that

the pin (2) is below the tab (3)

2410RA261 TG

2410RA267 TG

: Press filter base (1) over the

studs (arrows) onto the

carburetor

– Use STIHL press fluid to improve

assembly, b 16

: Push the buffer (1) completely

over the pins of the filter base (2)

– the shoulder of the pin must

protrude completely from the

opposite side of the buffer

– Install the choke rod, b 11.4

2410RA268 TG

2410RA269 TG

117MS 241 C

: Use wiring tool 5910 890 4000 to

press the ground wire (1) into the

guides (arrows) so that it lies

snug against the air guide shroud

and the marking (2) is at the edge

of the guide

: Use wiring tool 5910 890 4000 to

press the short-circuit wire (1)

into the guides (arrows) so that it

lies snug against the air guide

shroud and the marking (2) is at

the edge of the guide

– Check the switching functions of

the switch shaft

2410RA270 TG

2410RA271 TG

Versions with heating

: Insert lead (1) completely in

cable guide (arrow)

– Reassemble remaining parts in

reverse order

13.4 Air guide shroud

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove filter base

– Do not remove contact spring

and switch shaft, b 8.4

– Unplug the spark plug boot

: Pull plug connector (1) out of the

carburetor support mount (arrow)

2410RA169 TG

2410RA171 TG

: Hold the jack (1), press the

tab (arrow) and pull out the

plug (2) – do not tug on the leads

– Remove the carburetor, b 13.5

– Remove the throttle rod, b 11.5

– Remove carburetor support,

b 13.8

: Remove the plug (1)

: Remove diagnostic jack (1) with

bushing (2) from the

guides (arrows)

2410RA172 TG

2 1

2410RA272 TG

2410RA273 TG

118 MS 241 C

: Pry out and remove the cable

holder (1) at the pin (arrow)

: Remove grommet (1) and wiring

harness from the guides (arrows)

– Lay aside the wiring harness with

the filter base

: Remove screws (1)

2410RA274 TG

2410RA275 TG

2410RA276 TG

1 1

: Press the grommet (arrow) of the

fuel hose (1) downward and out

: Press tab (1) in the direction of

the clutch side and pry the air

guide shroud (2) out of the mount

: Press tab (1) in the direction of

the ignition side and pry the air

guide shroud (2) out of the mount

2410RA277 TG

2410RA278 TG

2410RA279 TG

: Pull the air guide shroud (1) over

the buffers and out of the mounts,

in the process, pushing the fuel

hose (2) through the hole (arrow)

: Press the manifold flange (1) out

of the air guide shroud (2) by

hand in the direction of the

cylinder while pulling of the air

guide shroud

– Pull the fuel hose out of the air

guide shroud

– Remove the air guide shroud

– Replace fuel hose, b 13.11.2

2410RA280 TG

2410RA281 TG

119MS 241 C

Installation

– Pull out the shutter and inspect it,

replace if necessary

: Slide the shutter (1) into the

guide until it snaps into place

: To pull the manifold flange (2)

into the hole of the air guide

shroud, place a string (1) that is

approx. 15 cm long around the

manifold flange

– To simplify assembly, coat the

manifold flange with

STIHL press fluid, b 16

2410RA282 TG2410RA283 TG

: Push new fuel hose (1) through

the opening (arrow)

: Pull the manifold flange (1)

through the opening by the ends

of the string (2), at the same time

pressing the air guide shroud (3)

against the manifold flange

– Remove the string

– To simplify installation, coat the

grommet with STIHL press fluid,

b 16

2410RA284 TG

2410RA285 TG

2410RA286 TG

: Pull the grommet of the fuel

hose (2) into the hole (arrow) in

the air guide shroud (1) until the

grommet entirely encloses the

hole

: Orient the grommet (1) of the fuel

hose (2) so the the straight

side (arrow) rests against the

edge of the air guide shroud

Shown without piston and cylinder

for a better view.

The lugs (2) of the air guide

shroud (1) must engage the

mounts (arrows) of the crankcase.

2410RA287 TG

2410RA288 TG

120 MS 241 C

: Guide the air guide shroud (1)

over the buffers (2) and push the

lugs into the mounts of the

crankcase

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

– Install the carburetor support,

b 13.8

– Install the throttle rod, b 11.5

2410RA289 TG

2410RA290 TG

2410RA291 TG

: Push the grommet (1) into the

mount until it is flush with the

edge of the air guide shroud

– Install wiring harness in the air

guide shroud, b 7.7.2

– Install the carburetor, b 13.5

– Install the filter base with the

attached wiring harness, b 8.4

– Reassemble remaining parts in

reverse order

13.4.1 Air guide shroud,

versions with manual fuel

pump

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove filter base

– Do not remove contact spring

and switch shaft, b 8.4

– Unplug the spark plug boot

– Remove wiring harness from the

air guide shroud and lay it aside

with the filter base, b 7.7.2

– Remove the carburetor, b 13.5

2410RA292 TG

– Remove the throttle rod, b 11.5

– Remove carburetor support,

b 13.8

: Remove fuel return line (1) at the

fuel pump (2) and pull it out of the

guides (arrows)

: Remove screws (1)

: Press the grommet (arrow) of the

fuel hose (1) downward and out

2410RA293 TG

2410RA294 TG

1 1

2410RA295 TG

121MS 241 C

: Press tab (1) in the direction of

the clutch side and pry the air

guide shroud (2) out of the mount

: Press tab (1) in the direction of

the ignition side and pry the air

guide shroud (2) out of the mount

: Press the manifold flange (1) out

of the air guide shroud (2) by

hand in the direction of the

cylinder while pulling the air guide

shroud out of the mounts

2410RA296 TG

2410RA297 TG

2410RA298 TG

: Pull fuel hose (1) and fuel return

line (2) out of the air guide shroud

– Remove the air guide shroud

: Ease out grommet (1) and

examine it, replace if necessary

– Replace fuel hose, b 13.11.2

– Replace fuel return line and fuel

suction hose, b 13.11.3

: Examine fuel pump and replace if

necessary, b 13.11.4

2410RA299 TG

2410RA538 TG

Installation

– Pull out the shutter and inspect it,

replace if necessary

: Slide the shutter (1) into the

guide until it snaps into place

– To simplify installation, coat the

outside of the grommet with

STIHL press fluid, b 16

: Press grommet (1) into

hole (arrow) until it encloses the

hole completely

2410RA442 TG

2410RA443 TG

122 MS 241 C

: To pull the manifold flange (2)

into the hole of the air guide

shroud, place a string (1) that is

approx. 15 cm long around the

manifold flange

– To simplify assembly, coat the

manifold flange with

STIHL press fluid, b 16

: Fit the air guide shroud (1)

: Push new fuel hose (2) through

the opening (arrow)

– Use STIHL press fluid to simplify

assembly, b 16

: Push the new fuel return line (3)

completely through the

grommet (4)

2410RA283 TG

2410RA444 TG

: Pull the manifold flange (1)

through the opening by the ends

of the string (2), at the same time

pressing the air guide shroud (3)

against the manifold flange

– Remove the string

– To simplify installation, coat the

grommet with STIHL press fluid,

b 16

: Position the air guide shroud (1)

and pull the grommet of the fuel

hose (2) into the hole (arrow)

until the grommet completely

encloses the hole

2410RA445 TG

2410RA446 TG

: Orient the grommet (1) of the fuel

hose (2) so the the straight

side (arrow) rests against the

edge of the air guide shroud

: Pull in the new fuel return line (1)

completely through the

grommet (2)

Shown without piston and cylinder

for a better view.

The lugs (2) of the air guide

shroud (1) must engage the

mounts (arrows) of the crankcase.

2410RA447 TG

2410RA448 TG

2410RA288 TG

123MS 241 C

: Guide the air guide shroud (1)

over the buffers (2) and push the

lugs into the mounts of the

crankcase

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

2410RA449 TG

2410RA450 TG

2410RA451 TG

: Orient the fuel return line (1) so

that the marking (arrow) is

located at the grommet (2)

: Starting at the grommet (2),

press the fuel return line (1) into

the guides (arrows) – the

marking (3) must be located at

the upper guide rib

– Route the fuel return line so that

it is snug – the fuel return line

must not form a loop between the

air guide shroud and the

grommet

– Install the carburetor support,

b 13.8

– Install the throttle rod, b 11.5

– Install the manual fuel pump,

b 13.11.4

The fuel return line must not be

kinked or pinched.

– Install the carburetor, b 13.5

2410RA452 TG

2410RA453 TG

: Push the grommet (1) into the

mount until it is flush with the

edge of the air guide shroud

– Install wiring harness in the air

guide shroud, b 7.7.2

– Install the filter base with the

attached wiring harness, b 8.4

– Reassemble remaining parts in

reverse order

13.4.2 Air guide shroud version

with heating

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove filter base

– Do not remove contact spring

and switch shaft, b 8.4

– Unplug the spark plug boot

– Remove wiring harness from the

air guide shroud and lay it aside

with the filter base, b 7.7.2

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

2410RA292 TG

124 MS 241 C

: Pull contact sleeve (1) out of

heating switch (2)

: Remove lead (1) from the

guides (arrows)

: Remove plug connection with

insulating tube (2) and generator

lead (1) from the guides (arrows)

2410RA454 TG

2410RA455 TG

2410RA456 TG

: Slide insulating tube (1) towards

generator and disconnect plug

connection

: Pull insulating tube (1) off of the

generator lead (2)

: Remove screws (3)

: Press the grommet (arrow) of the

fuel hose (1) downward and out

2410RA457 TG

2410RA458 TG

1 2

3 3

2410RA459 TG

: Press tab (1) in the direction of

the clutch side and pry the air

guide shroud (2) out of the mount

: Press tab (1) in the direction of

the ignition side and pry the air

guide shroud (2) out of the mount

: Press the manifold flange (1) out

of the air guide shroud (2) by

hand in the direction of the

cylinder while pulling the air guide

shroud out of the mounts

2410RA460 TG

2410RA461 TG

2410RA462 TG

125MS 241 C

: Press out the grommet (1) of the

generator lead (2) in the direction

of the generator and pull the

generator lead (2) out of the

hole (arrow)

– Pull the grommet off of the

generator lead – to make it

easier, twist the grommet while

pulling it off

: Pull the fuel hose (1) out of the air

guide shroud

: Pull the wiring harness (2) out of

the air guide shroud through the

grommet (3)

– Remove air guide shroud with

heating switch and ground wire

2410RA463 TG

2410RA464 TG

: Ease out grommet (1) and

examine it, replace if necessary

: Remove ground wire (1) from the

guide (arrow)

: Push the holder (2) with the

heating switch out of the mount

– Examine heating switch and

replace if necessary, b 14.4

– Examine ground wire and

replace if necessary, b 14.4

– Replace fuel hose, b 13.11.2

2410RA465 TG

2410RA466 TG

Installation

– Pull out the shutter and inspect it,

replace if necessary

: Slide the shutter (1) into the

guide until it snaps into place

– To simplify installation, coat the

outside of the grommet with

STIHL press fluid, b 16

: Press grommet (1) into

hole (arrow) until it encloses the

hole completely

2410RA467 TG

2410RA468 TG

126 MS 241 C

: Push grommet (1) onto the

generator lead (2) so that the

conical area (arrow) faces the

generator – to make it easier,

twist the grommet while pushing

it on

The generator lead (1) must be

seated completely in the

guide (arrow).

: To pull the manifold flange (2)

into the hole of the air guide

shroud, place a string (1) that is

approx. 15 cm long around the

manifold flange

2410RA469 TG

1 2

2410RA413 TG

2410RA471 TG

– To simplify assembly, coat the

manifold flange with

STIHL press fluid, b 16

: Fit the air guide shroud (1)

: Push new fuel hose (2) through

the opening (arrow)

– To simplify installation of the

grommet, coat the outside of the

grommet with STIHL press fluid,

b 16

: Push the generator lead (1)

through the hole on the

side (arrow) and press the

grommet (2) into the hole until it

completely encloses the hole

2410RA286 TG

2410RA472 TG

The crimped side of the ground

wire (2) must face the intake elbow.

: Press holder (1) with heating

switch as far as it will go into the

guides (arrows)

: Push lead (1) with terminal

socket (2) through the right

hole (see illustration) of the

grommet (3) and pull it in until the

connector (4) has been pulled

through the grommet (3)

: Push lead (5) with terminal

socket (6) through the left

hole (see illustration) of the

grommet (3)

2410RA473 TG

2410RA474 TG

127MS 241 C

: Pull in wiring harness (1) until the

protective tube (2) rests against

the grommet

: Pull the manifold flange (1)

through the opening by the ends

of the string (2), at the same time

pressing the air guide shroud (3)

against the manifold flange

– Remove the string

– To simplify installation, coat the

grommet with STIHL press fluid,

b 16

2410RA475 TG

2410RA476 TG

2410RA477 TG

: Position the air guide shroud (1)

and pull the grommet of the fuel

hose (2) into the hole (arrow)

until the grommet completely

encloses the hole

: Orient the grommet (1) of the fuel

hose (2) so the the straight

side (arrow) rests against the

edge of the air guide shroud

Shown without piston and cylinder

for a better view.

The lugs (2) of the air guide

shroud (1) must engage the

mounts (arrows) of the crankcase.

2410RA478 TG

2410RA288 TG

: Guide the air guide shroud (1)

over the buffers (2) and push the

lugs into the mounts of the

crankcase

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

: Press the air guide shroud (1)

into the mount until the tab (2)

snaps into place

2410RA479 TG

12 2

2410RA480 TG

2410RA481 TG

128 MS 241 C

: Pull in generator lead (1) and

wiring harness (2)

: Position cable lug (3) so that the

crimped side faces upward and

insert screws (4)

: Push ground wire (5) into the

guide (arrow) and tighten

screws (4)

– Press the plug connections

together completely, b 1

: Route generator lead (1) behind

the wiring harness (2)

: Slide insulating tube (3) over the

generator lead (1)

2410RA482 TG

1 2

2410RA483 TG

: Push together the connector (1)

and the terminal socket (2)

: Slide insulating tube (3) over the

plug connection

: Press the plug connection with

insulating tube (1) into the center

of the guide

: Route the generator lead (2) in

the guides (arrows) so that it lies

snug against the air guide shroud

and forms a loop (3) at the

insulating tube (1)

2410RA484 TG

1 2 3

2410RA485 TG

: Push the contact sleeve (1) into

the heating switch (2) as far as it

will go

: Press the lead (1) completely into

the guides (arrows) so that it

rests snug against the air guide

shroud

The generator lead must be routed

along the lower guide below the

lead of the heating switch.

– Install the carburetor support,

b 13.8

– Install the throttle rod, b 11.5

– Install the carburetor, b 13.5

2410RA486 TG

2410RA487 TG

129MS 241 C

: Push the grommet (1) into the

mount until it is flush with the

edge of the air guide shroud

– Install wiring harness in the air

guide shroud, b 7.7.2

– Install the filter base with the

attached wiring harness, b 8.4

– Reassemble remaining parts in

reverse order

13.5 Carburetor

– Pull off the filter base over the

studs and lay it aside with the

attached wiring harness, b 8.4

– Open filler cap and drain fuel tank

– Collect fuel in a clean container,

b 1

The fuel hose may only be removed

when the tank filler cap is open.

2410RA292 TG

: Pull holder (1) of the switchgear

over the studs (arrows) and lay it

aside

Versions with manual fuel pump

: Disconnect the fuel hose (1)

: Push out the holder (1) with the

fuel pump on the air guide

shroud (2) and lay it on top of the

air guide shroud

2410RA239 TG

2410RA241 TG

2410RA242 TG

All versions

: Pull plug connector (1) out of the

carburetor support mount (arrow)

: Hold the jack (1), press the

tab (arrow) and pull out the

plug (2) – do not tug on the leads

Version with heating

: Remove blade receptacle (1)

: Remove heating element (2)

from the studs

2410RA243 TG

2410RA172 TG

2 1

2410RA240 TG

130 MS 241 C

: Pull off carburetor (1) slightly and

pull lead (2) out of the

guide (arrow)

: Disconnect the fuel hose (1) from

the connector (arrow).

: Pull insulating tube (1) with plug

connection out of the

guide (arrow), slide insulating

tube (1) in direction of the

thermostatic switch and

disconnect plug connection

: Pull off carburetor (2) with

switchgear (3) and thermostatic

switch (4)

2410RA470 TG

2410RA488 TG

2410RA489 TG

1 3

All versions

: Disconnect the fuel hose (1) from

the connector (arrow).

: Pull off carburetor (1) with

switchgear (2)

– Remove switchgear at the

carburetor, b 8.4

: Check ring (1) and sealing

ring (2) and replace if necessary

: Check connector (3) – in case of

a damaged connector (3), the

carburetor must be replaced

2410RA488 TG

2410RA491 TG

2410RA492 TG

– Examine the carburetor and

repair or replace it if necessary,

b 13.5, b 13.6

– Replace fuel hose, b 13.11.2

Versions with manual fuel pump

– Replace fuel suction hose,

b 13.11.3

Installation

Versions with manual fuel pump

: Check seat of the fuel return

line (1), if necessary. press it

completely into the

guides (arrows)

Versions with heating

: Check seat of the heating switch

lead (1) and generator lead (2), if

necessary. press completely into

the guides (arrows)

2410RA493 TG

2410RA494 TG

131MS 241 C

All versions

Washer (1) must be fitted.

Ring (1) must be in place.

Sealing ring (2) must be in place.

Connector (3) must engage in the

hole of the manifold flange.

– Install the switchgear wiring

harness on the carburetor, b 8.4

: Slide on the carburetor (1) over

the studs (arrows) until it is flush

with the studs

2410RA495 TG

2410RA492 TG

2410RA496 TG

: Push new fuel hose (1) onto the

connector (2) so that the

tab (arrow) faces the throttle

shaft lever and fits against the

connector evenly

Version with heating

– Press the plug connection

together completely, b 1

: The lead (1) of the thermostatic

switch must be seated in the

guides (arrows) and run behind

the stud (2)

: Push insulating tube (1) onto

lead (2) of the thermostatic

switch

2410RA497 TG

2410RA498 TG

2410RA499 TG

: Push together the connector (3)

and the terminal socket (4)

: Slide the insulating tube (1) over

the plug connection, if necessary,

with gentle twisting motions

: Press the plug connection with

insulating tube (1) into the center

of the guide (arrow)

The lead (1) of the thermostatic

switch must run along the loop (2)

above the generator lead.

: Press lead (1) completely into the

guide (arrow)

2410RA416 TG

2410RA503 TG

132 MS 241 C

All versions

: Push on the carburetor (1) further

: Orient plug (1) and jack (2) that

the tab (3) lines up with the

opening (arrow) – do not twist the

leads

: Plug connector (1) into jack (2)

until the tab (3) clicks into place

2410RA504 TG

2410RA188 TG

1 2

: Press the plug connection (1)

into the mount (2) of the

carburetor support so that the

tab (arrow) engages and snaps

into place in the recess of the

plug connection

- Plug connection (1) must be

seated firmly in the mount (2)

– Push on the carburetor as far as

it will go – pay attention to cable

routing and make sure not to

pinch any leads

Versions with heating

: Slide the heating element (1)

over the studs so that the hole

engages the pin (2)

: Orient the crimped side of the

blade receptacle (3) so that it

faces the carburetor

: Push the blade receptacle (3)

completely onto the connector

tab (arrow)

2410RA505 TG

1 2

2410RA258 TG

Versions with manual fuel pump

: Push the holder (1) with the fuel

pump into the mount of the air

guide shroud (2) as far as it will

go; push new fuel hose (3) onto

the connectors (arrows)

: Fuel return line (4) must be

seated completely in the

guide (5); if necessary, press the

fuel return line (4) into the

guide (5) again

2410RA259 TG

133MS 241 C

All versions

: Push the holder (1) of the

switchgear over the studs so that

the tab rests against the

pin (arrow)

– Install the filter base with the

attached wiring harness, b 8.4

– Install the choke rod, b 11.4

– Install air filter, b 13.1

– Check correct functioning

– Set throttle trigger to full

throttle; the throttle shutter on the

carburetor must be open all the

way

– Reassemble remaining parts in

reverse order

13.5.1 Leakage test

The tank vent must also be checked

and replaced if problems develop

with the carburetor or fuel supply,

b 13.10

The carburetor can be tested for

leaks with the pump

0000 850 1300.

– Remove filter base with attached

wiring harness and lay it aside,

b 8.4

– Remove the carburetor, b 13.5

2410RA260 TG

: Push the fuel line (1)

1110 141 8600 onto the double

connector (2) 0000 855 9200

: Push the fuel line with double

connector onto the fuel

port (arrow)

– Push the delivery hose of the

pump 0000 850 1300 onto the

double connector

: Push ring (1) to the right and

pump air into the carburetor until

the pressure gauge (2) shows a

pressure of approx. 0.8

bar (80 kPa)

If this pressure remains constant,

the carburetor is airtight. However, if

the pressure drops, this may have

the following causes:

1. Metering diaphragm or gasket is

damaged, replace if necessary,

b 13.6.1

2410RA506 TG

2410RA507 TG

2. The inlet valve is not sealing

(foreign objects in the valve

seat,

sealing cone of the inlet needle

is damaged or

inlet control lever is sticking),

remove to clean,

b 13.1

3. Pump diaphragm or

gasket damaged,

replace if necessary, b 13.6.3

– Check tank vent if necessary,

b 13.10.1

– After completing the test, slide

ring (1) to the left and vent the

system, then disconnect fuel line

from elbow connector of

carburetor

– Install the carburetor, b 13.5

– Install the filter base with the

attached wiring harness, b 8.4

– Reassemble remaining parts in

reverse order

13.6 Repairing the carburetor

All versions are controlled by the

M-Tronic system, thus no adjusting

screws are required or present on

the carburetor. Solenoid and special

bolt for idle stop may not be

modified or removed; if they are

damaged, the carburetor must be

replaced.

134 MS 241 C

13.6.1 Metering diaphragm

– Troubleshooting, b 3.6

– Remove the carburetor, b 13.5

: Take out the screws (arrows)

: Remove the end cover (1)

If the gasket and diaphragm are

stuck to the carburetor, they must

be removed very carefully.

: Check sealing ring (1) and

replace if necessary

– For versions with manual fuel

pump, check connector (2),

replace end cover if necessary

2410RA357 TG

2410RA371 TG

: Carefully separate the metering

diaphragm (1) and gasket (2)

The diaphragm material is

subjected to continuous alternating

stresses and eventually shows

signs of fatigue. In other words, the

diaphragm distorts and swells and

must be replaced.

– Examine the metering diaphragm

for signs of damage and wear, fit

a new gasket

Installation

– Note the order in which the

metering diaphragm (1) and

gasket (2) are installed

: Align the gasket (2) and metering

diaphragm (1) so that the small

holes on the tabs engage the

pins (arrows)

2310RA256 TG

2410RA358 TG

: Orient the end cover (1) so that

the connector (3) faces the choke

shutter and the holes align

: Fit and screw in the screws (2) –

do not tighten them

– Check that the metering

diaphragm and gasket are

correctly seated, then tighten

down the screws crosswise

The sealing ring (arrow) must not be

damaged.

– Reassemble remaining parts in

reverse order

2410RA359 TG

135MS 241 C

13.6.2 Inlet needle

– Remove the metering

diaphragm,

b 13.6.1

: Remove screw (1)

: Pull the inlet control lever (2) with

spindle (3) out of the groove in

the inlet needle

The spring under the inlet control

lever may pop out.

: Pull out the inlet needle (1)

: Take out and examine the

spring (2), replace if necessary

2410RA372 TG

2410RA360 TG

: The inlet needle must be

replaced if a circular

indentation (arrow) is visible on

the tip of its sealing cone

Installation

: Fit the inlet needle (1)

: Fit spring (2) in bore

: First fit the spindle (2) of the inlet

control lever (3) at the conical

seat (arrow) of the spring, then

slide the clevis on the inlet control

lever into the groove on the inlet

needle (1)

165RA348 TG

2410RA361 TG

2410RA373 TG

Ensure that the spring locates on

the nipple of the inlet control lever.

– Press the inlet control lever down

and secure it with the screw.

– Check that the inlet control lever

moves easily

– Install the metering diaphragm,

b 13.6.1

13.6.3 Pump diaphragm

– Troubleshooting, b 3.6

– Remove the carburetor, b 13.5

: Remove screw (1)

: Remove the end cover (2)

If the gasket and pump diaphragm

are stuck to the carburetor, they

must be removed very carefully.

2410RA375 TG

136 MS 241 C

Version with handle and

carburetor heating

: Remove screw (1)

: Remove thermostatic switch (2)

: Remove the end cover (3)

If the gasket and pump diaphragm

are stuck to the carburetor, they

must be removed very carefully.

All versions

– Carefully remove the pump

diaphragm with gasket from the

end cover

: Carefully separate the pump

diaphragm (2) and gasket (1)

– always use a new gasket

The diaphragm material is

subjected to continuous alternating

stresses and eventually shows

signs of fatigue. In other words, the

diaphragm distorts and swells and

must be replaced.

2410RA362 TG

2310RA266 TG

– Examine the pump diaphragm for

signs of damage and wear, fit a

new gasket

– Examine fuel strainer for

contamination and damage,

clean or replace if necessary

: Pull fuel strainer (1) with needle

out of the carburetor housing and

clean or replace it

– Reassemble parts in reverse

order

Installation

: Position gasket (1) and pump

diaphragm (2) on the end

cover (3) so that the

protrusions (arrows) match and

are secured in the pins (4)

2310RA267 TG

2310RA268 TG

– Position the end cover (1) on the

carburetor housing from below so

that the gasket and pump

diaphragm remain secured to the

end cover

: Orient the end cover (1) so that

the protrusion (arrow) faces the

lever of the throttle and choke

shaft

Version with heating

: Move the end cover (1) back and

forth slightly until the pegs on the

end cover engage in the holes in

the carburetor housing

: Position the thermostatic

switch (2) so that it rests against

the raised part (arrow)

– Check that the pump diaphragm

and gasket are correctly seated

: Screw in the screw (3) and

tighten it

2410RA363 TG

2410RA364 TG

137MS 241 C

: Press lead (1) into the

guides (arrows) so that is is

behind the peg (2)

: Slide on the insulating tube (3)

All versions

– Move the end cover (1) back and

forth slightly until the pegs on the

end cover engage in the holes in

the carburetor housing

– Check that the pump diaphragm

and gasket are correctly seated

: Screw in the screw (2) and

tighten it

– Reassemble remaining parts in

reverse order

13.6.4 Lead retainer

– Remove the carburetor, b 13.5

– Remove the wiring harness with

switchgear, b 8.4

2410RA374 TG

1 32

2410RA376 TG

: Remove screw (1) and pull out

cable holder (2)

Installation

: Orient the cable holder (1) so that

the closed side faces the

carburetor and the pin lines up

with the mount (arrow)

: Press in the cable (1) as far as it

will go

: Screw in the screw (2) and

tighten it

– Install the wiring harness with

switchgear, b 8.4

– Reassemble remaining parts in

reverse order

13.6.5 Lever of the throttle shaft

– Remove the carburetor, b 13.5

– Troubleshoot carburetor, b 3.6

2410RA365 TG

2410RA366 TG

: Press out the circlip (1) and

remove the lever (2)

Installation

: Orient lever (1) so that the hook

engages the lever of the choke

shaft (arrows)

: Slide the lever (1) onto the

throttle shutter shaft (2) so that it

aligns with the flat faces

: Push circlip (3) into place

: Check correct functioning

– Lever (1) must engage in

lever (4) (arrows)

– Reassemble remaining parts in

reverse order

2410RA367 TG

2410RA368 TG

138 MS 241 C

13.6.6 Lever of the choke shaft

– Remove the carburetor, b 13.5

– Troubleshoot carburetor, b 3.6

: Push out circlip (1)

: Remove lever (2)

Installation

: Orient lever (1) so that it faces

the throttle shaft and the flat

face (arrow) faces the solenoid

valve

: Slide the lever (1) onto the choke

shaft (2) so that it aligns with the

flat faces of the choke shaft

: Push circlip (3) into place

2410RA369 TG

2410RA370 TG

– Install carburetor, check correct

functioning

– Lever (1) must actuate the

microswitch, b 13.5, b 8.2.5

– Reassemble remaining parts in

reverse order

13.7 Carburetor adjustment

The carburetor is adjusted by the

M-Tronic, thus no manual

adjustments to the carburetor are

necessary or possible.

Position of the special bolt (1) must

not be changed

– changing the factory default

setting leads to impaired engine

performance.

Solenoid valve (2) must not be

dismantled.

The solenoid valve must not be

twisted when disconnecting the

plug; if necessary, hold the solenoid

valve in place during disconnection

of the plug.

If the solenoid valve is twisted, twist

it back clockwise as far as it will go.

– In case of malfunctions, check

M-Tronic, b 8.2

2410RA377 TG

13.8 Carburetor bracket

– Remove filter base with attached

wiring harness and lay it aside,

b 8.4

– Remove switchgear and

carburetor and lay them aside,

b 8.4

: Remove the washer (1)

: Pull throttle rod (1) out of the

guide (arrow) and set it aside

2410RA508 TG

2410RA509 TG

139MS 241 C

: Press the manifold flange (1) out

of the carburetor support (2) by

hand in the direction of the

cylinder while pulling off the

carburetor support

– Remove carburetor support,

check it and replace if necessary

– Examine intake elbow, replace if

necessary, b 13.9

Installation

: To pull the manifold flange (2)

into the hole of the carburetor

support, place a string (1) that is

approx. 15 cm long around the

manifold flange

2410RA510 TG

2410RA511 TG

– Coat manifold flange with STIHL

press fluid, b 16

: Pull the manifold flange (2)

through the opening by the ends

of the string (1), at the same time

pressing the carburetor

support (3) against the manifold

flange

– Remove the string

: Orient the carburetor support (1)

so that the openings (arrows)

rest against the studs (2)

2410RA512 TG

2410RA513 TG

The hole (arrow) of the intake

elbow (1) must be unobstructed;

clean if necessary – a fouled hole

can lead to impaired engine

performance, b 3.7.

Versions with manual fuel pump

: Check seat of the fuel return

line (1), if necessary. press it

completely into the

guides (arrows)

2410RA514 TG

2410RA426 TG

140 MS 241 C

Versions with heating

: Check seat of the lead (1) to the

heating switch; if necessary.

press it completely into the

guides (arrows)

: Press the throttle rod (1) into the

guide (arrow) until it clicks into

place.

: Slide on the washer (1)

– Reassemble remaining parts in

reverse order

2410RA427 TG

2410RA509 TG

2410RA515 TG

13.9 Intake elbow

A damaged intake elbow may lead

to impaired engine performance.

– Troubleshooting, b 3.7

– Remove shroud, b 6.4

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4

Versions with manual fuel pump,

b 13.4.1,

Versions with heating, b 13.4.2

: Take out the screws (arrows)

: Remove intake elbow (1)

– Examine intake elbow and

replace if necessary. The

slightest damage may lead to

impaired engine performance,

b 13.9

2410RA547 TG

: Examine and clean the mating

surfaces (arrows), b 16

The mating surfaces must be in

perfect condition and without any

damage whatsoever. Parts with

damaged mating surfaces must be

replaced.

: The hole (1) of the intake

elbow (2) must be unobstructed;

clean if necessary – a fouled hole

can lead to impaired engine

performance

2410RA548 TG2310RA359 TG

141MS 241 C

Installation

: Position intake elbow (1) against

cylinder

: Insert and tighten down the

screws (arrows)

– Install air guide shroud, b 13.4

Versions with manual fuel pump,

b 13.4.1,

Versions with heating, b 13.4.2

– Install the carburetor support,

b 13.8

– Reassemble remaining parts in

reverse order

13.10 Tank vent

13.10.1 Testing

If problems develop in the

carburetor or fuel supply, the tank

vent must always also be tested and

replaced if necessary. Correct

functioning is determined by testing

the fuel tank under vacuum or at

gauge pressure via the fuel hose.

– Open filler cap and drain fuel

tank, b 1

– Close the filler cap

– Remove the carburetor, b 13.5

2410RA549 TG

: Push the connector (1)

0000 855 9200 into the fuel

hose (arrow)

Versions with manual fuel pump

: Close fuel suction hose (1) with a

suitable stopper (2)

Testing with negative pressure

: Slide ring (1) to the left and

connect the pump (2)

0000 850 1300 to the double

nipple (arrow)

– Create vacuum in fuel tank

2410RA558 TG

2410RA516 TG

2410RA517 TG

Pressure is equalized via the tank

vent. A negative pressure must not

build up inside the fuel tank.

– Clean the area around the tank

vent

– Replace the tank vent or tank

housing if necessary, b 13.10 or

b 13.11.5

Testing with gauge pressure

: Slide ring (1) to the right and

connect the pump (2)

0000 850 1300 to the double

nipple (arrow)

– Create excess pressure in fuel

tank

– Actuate the pump until the

pressure gauge shows a

pressure of 0.5 bar. If this

pressure remains constant for at

least 20 seconds, the tank and

tank vent are airtight. If the

pressure drops, the leak must be

located and the defective part

replaced.

– Reassemble parts in reverse

order

2410RA518 TG

142 MS 241 C

13.10.2 Removal and installation

– Remove shroud, b 6.4

: Remove screw (1)

: Press tank housing (1)

downward and maintain spacing

by inserting wooden assembly

block (2) 1108 893 4800

: Remove cover (1)

2310RA365 TG

2310RA366 TG

2310RA367 TG

: Pry out the tank vent (1) via the

mounting rib (arrow)

Always fit a new tank vent.

– Wet O-ring of new tank vent with

STIHL press fluid, b 16

– Press the new tank vent in by

hand until it audibly engages

: Position cover (1) so that it

engages the peg (arrow)

2310RA368 TG

2310RA369 TG

: Remove wooden assembly block

and raise tank housing (1) until

the holes (arrow) in tank housing,

cover and antivibration spring

align

: Screw in the screw (1) and

tighten it

– Reassemble remaining parts in

reverse order

2310RA370 TG

2310RA365 TG

143MS 241 C

13.11 Fuel intake

13.11.1 Pickup body

Impurities which are entrained into

the fuel tank with the fuel are

trapped by the pick-up body. With

time, the fine pores in the pick-up

body become clogged with very fine

dirt particles. This reduces the

intake diameter and fuel can no

longer be delivered in sufficient

quantities.

Always check the fuel tank and pick-

up body first if problems develop in

the fuel supply.

– Troubleshooting, b 3.6 or

b 3.7

Clean the fuel tank if necessary.

– Open the filler cap and drain the

tank.

– Fill a little clean gasoline into the

tank, close the tank and shake it

thoroughly.

– Reopen the tank and empty it

– Ensure that the fuel is disposed

of correctly and without harming

the environment, b 1

– Open the filler cap

: Use hook 5910 893 8800 to pull

the pickup body (1) out of the fuel

tank

Take care not to overextend the fuel

hose.

– Pull off pickup body (1) and

examine it, replace if necessary

– Reassemble parts in reverse

order

13.11.2 Fuel hose

– Open the filler cap

– Remove the pickup body,

b 13.11.1

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4

Versions with heating, b 13.4.2

2310RA371 TG

: Remove screw (1)

Versions with heating

: Remove screw (1) on front

handle

2310RA372 TG

2410RA302 TG

2410RA303 TG

144 MS 241 C

Versions with QuickStop Super

Before lowering the tank housing,

loosen the brake cable holder,

because the sleeve of the brake

cable can be pulled out of the

adjusting screw when the tank

housing is lowered

– Brake cable adjustment can be

negatively affected.

: Unscrew screw (1) pull

support (2) out of the mount

All versions

– Lower the tank housing

: Pull out fuel hose (1) with

connector

2310RA057 TG2410RA519 TG

: Remove connector (1) from fuel

hose (2)

– Remove the pickup body,

b 13.11.1

: Pull the fuel suction hose (1) out

of the inside of the tank

– Replace fuel hose and fuel

suction hose; check connector,

replace if necessary

Installation

: Push fuel suction hose (1) into

hole (arrow) in fuel tank

2310RA378 TG

2410RA520 TG

2410RA521 TG

– Use STIHL press fluid to simplify

assembly, b 16

: Orient the fuel suction hose (1)

and press it into the hole in the

housing as far as it will go – the

flange must be flush with the

guide (arrow)

: Orient the flat surface of the

connector (1) so that it faces the

tab of the fuel hose (2) (arrows) –

tab must rest evenly against the

connector

: Push the connector (1) into the

fuel hose (2) as far as it will go

2410RA522 TG

2310RA382 TG

145MS 241 C

: Push fuel hose (1) with the

connector (2) in front into the fuel

suction hose so that it is between

the ribs (arrows)

Versions with QuickStop Super

: Push fuel hose (1) with the

connector (2) in front under the

brake cable and into the fuel

suction hose so that it is between

the ribs (arrows)

2410RA523 TG

2410RA524 TG

: Orient the fuel hose (1) so that it

is underneath the brake cable (2)

in accordance with the illustration

and runs toward the ignition side

All versions

: Insert antivibration spring (1)

through the opening (arrow)

: Raise tank housing (2)

– Insert and tighten down the screw

2310RA525 TG

2310RA387 TG

Versions with QuickStop Super

: Press brake cable holder with the

pin (1) through the opening and

into the mount (arrow)

: Screw in the screw (2) and

tighten it

: Fit the plug (1) of the antivibration

spring

: Screw in the screw (2) and

tighten it

2310RA059 TG2410RA306 TG

146 MS 241 C

Versions with heating

: Fit the plug (1) of the antivibration

spring on the front handle

: Screw in the screw (2) and

tighten it

– Check position of the fuel hose

and correct it if necessary,

b 13.11.2

: Use hook 5910 893 8800 to pull

the fuel suction hose (1) out of

the fuel tank

Take care not to overextend the fuel

suction hose.

– Fit the pickup body, b 16

– Install air guide shroud, b 13.4

Versions with heating, b 13.4.2

2410RA307 TG

2410RA526 TG

– Install the carburetor support,

b 13.8

– Install the carburetor, b 13.5

– Close the filler cap

– Reassemble remaining parts in

reverse order

13.11.3 Fuel hoses manual fuel

pump

– Open the filler cap

– Remove the pickup body,

b 13.11.1

– Remove filter base, b 13.3

: Disconnect the fuel suction

hose (1) from the

connectors (arrows)

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4.1

– Lower the tank housing,

b 13.11.2

2410RA527 TG

Versions with QuickStop Super

Before lowering the tank housing,

loosen the brake cable holder,

because the sleeve of the brake

cable can be pulled out of the

adjusting screw when the tank

housing is lowered

– Brake cable adjustment can be

negatively affected.

: Unscrew screw (1) pull

support (2) out of the mount

: Remove fuel hose (1),

b 13.11.2

2310RA057 TG2410RA528 TG

147MS 241 C

: Pull out connector (1) with fuel

return line (2)

: Remove connector (1) from fuel

return line (2)

: Pry out grommet (1)

– Replace fuel return line, check

connectors and grommet and

replace if necessary

2410RA529 TG

2310RA393 TG

2410RA550 TG

: Remove fuel suction hose (1),

b 13.11.2

Installation

: Install fuel suction hose (1),

b 13.11.2

– Use STIHL press fluid to simplify

assembly, b 16

: Press grommet (1) into

hole (arrow) of the fuel tank until

it encloses the hole completely

2410RA530 TG

2410RA551 TG

2410RA552 TG

: Push the connector (1) into the

fuel return line (2) as far as it will

Versions with QuickStop Super

: Guide the fuel return line (1)

connector-first under the brake

cable (2)

: Guide the connector (3) with the

fuel return line (1) between the

ribs (arrows) and push it into

grommet (4)

2310RA399 TG

2410RA553 TG

148 MS 241 C

Fuel return line (1) must be

underneath the brake cable (2) and

run around the brake cable in

accordance with the illustration.

: Install fuel hose (1), b 13.11.2

– Install air guide shroud,

b 13.4.1

– Install the carburetor support,

b 13.8

– Install the carburetor, b 13.5

2410RA554 TG

2410RA555 TG

: Push the new fuel return line (1)

into the long connector (2) as far

as it will go

: Push the new fuel suction

hose (3) onto the short

connector (4) and the

connector (5) on the carburetor

as far as it will go

– Check correct functioning

– Fuel must be drawn in when the

fuel pump is actuated

: Press fuel return line (1)

completely into the guide (arrow)

– Check proper functioning with

manual fuel pump, b 13.11.4

– Reassemble remaining parts in

reverse order

2410RA531 TG

1 2

2410RA532 TG

13.11.4 Manual fuel pump

– Remove shroud, b 6.4

: Disconnect the fuel suction

hose (1) and fuel return line (2)

from the connectors (arrows)

– Replace fuel hoses, b 13.11.3

: Push holder (1) with fuel

pump (2) out of the

guides (arrows) of the air guide

shroud

2410RA533 TG

2410RA534 TG

1 2

149MS 241 C

: Press the lugs (arrows) together

and push out the fuel pump (1)

– Examine fuel pump and replace

if necessary

Installation

: Orient fuel pump (1) so that the

tab (3) faces the recess (arrow)

: Press fuel pump (1) into

holder (2) until the lugs engage

2410RA535 TG

2410RA536 TG

: Push holder (1) with fuel

pump (2) as far as it will go into

the guides (arrows) of the air

guide shroud

: Push the fuel return hose (1) onto

the long connector (2) as far as it

will go

: Push the fuel suction hose (3)

onto the short connector (4) and

the connector (5) on the

carburetor as far as it will go

– Check correct functioning

– Fuel must be drawn in when the

fuel pump is actuated

– Reassemble remaining parts in

reverse order

2410RA537 TG

1 2

2410RA531 TG

1 2

13.11.5 Tank housing

– Empty the fuel tank, b 1

– Remove the front handle,

b 10.4

Versions with heating, b 10.4.1

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4

Versions with manual fuel pump,

b 13.4.1,

Versions with heating, b 13.4.2

– Versions with QuickStop Super,

unhook brake cable at brake

lever, b 5.4

– Remove actuating lever, b 11

: Remove screw (1)

2410RA557 TG

150 MS 241 C

: Remove screw (1)

: Remove the chain catcher (2)

: Pry antivibration spring (1) out of

the bearing seat (2)

: Pull tank housing (1) out of the

crankcase (2)

Versions with QuickStop Super

– Pull out the tank housing, at the

same time pulling the brake cable

out of the crankcase

2410RA300 TG

2310RA410 TG

2410RA539 TG

All versions

– Examine the tank housing and

replace it if necessary.

Those parts of the old tank housing

which are not supplied with the new

tank housing must be reused – see

spare parts list.

– Replace fuel hoses

: Check stop buffers (1) on the

ignition and clutch sides, replace

if necessary, b 10.3.2

Installation

: Guide tank housing (1) with the

narrow part (2) in front into the

mount in the crankcase

2410RA540 TG

2410RA541 TG

: Press antivibration spring (1) into

the bearing seat (2) so that the

tab (3) engages in the

opening (arrow)

: Push the chain catcher (3) into

the mount so that it engages

under the bumper strip (3)

: Screw in the screw (1) and

tighten it

2310RA414 TG

2410RA301 TG

151MS 241 C

Versions with QuickStop Super

: Push the brake cable (1) with the

short hook (4) in front past the

right side of the fuel hose (3) and

through the opening (arrow)

Versions with manual fuel pump

: Push the brake cable (1) with the

short hook (4) in front past the

right side of the fuel hose (3) and

the fuel return line (2) and

through the opening (arrow)

: Push brake cable (1) with short

hook (2) in front through the

hole (arrow) in the crankcase

2410RA542 TG

2410RA543 TG

11 2

All versions

– Install air guide shroud, b 13.4

Versions with manual fuel pump,

b 13.4.1,

Versions with heating, b 13.4.2

: Insert antivibration spring (1)

through the opening (arrow) in

the crankcase

2310RA416 TG

: Raise tank housing (2)

: Screw in the screw (1) and

tighten it

– Install the front handle, b 10.4

Versions with heating, b 10.4.1

– Versions with QuickStop Super,

hook on brake cable at brake

lever, b 5.4

– Install the carburetor support,

b 13.8

– Install the carburetor, b 13.5

– Install actuating lever, b 11

– Reassemble remaining parts in

reverse order

2310RA417 TG

152 MS 241 C

14. Heating

14.1 Carburetor heating

The heating element is installed

between the switchgear halter and

the carburetor. Power is provided to

the heating element via leads.

The heating element is regulated by

the thermostatic switch on the

underside of the carburetor.

The heating element and the

thermostatic switch must also be

checked if running problems occur

when the cold engine is idling or

running at part load, particularly at

sub-zero temperatures.

Idling problems with a hot engine

may also indicate a fault in the

heating element of the thermostatic

switch.

14.1.1 Check overall system

In the function check of the overall

system, the generator and heating

elements are checked. Precondition

is an ambient temperature of at

least +20°C (68°F).

If the temperature is below + 13 °C

(55 °F), the thermostatic switch may

be closed and produce false

readings.

– Check the carburetor heating in

accordance with the

troubleshooting chart carburetor

heating, b 14.2

– Remove the air filter, b 13.1

– Set ohmmeter to measuring

range "Ω"

: Clip one of the two test leads onto

a nut of the baffle and the other

onto a cylinder fin

If the system is OK, the ohmmeter

will show a reading of approx. 10 Ω

in the measuring range "Ω".

If the reading obtained is outside

this tolerance, each component

must be tested separately.

14.1.2 Check heating element

– Remove filter base, b 13.1

– Pull of switchgear and set it

aside, pull out the carburetor

somewhat in the direction of the

handle, b 13.5

: Remove blade receptacle (1)

: Remove heating element (2)

from the studs

100

2410RA378 TG2410RA379 TG

: Clip one test lead to the heating

element, the second test lead to

the blade receptacle

If the heating element is OK, the

ohmmeter will show a reading

of approx. 12 Ω in the measuring

range "Ω".

Installation

: Slide the heating element (1)

over the studs so that the hole

engages the pin (2)

: Orient the crimped side of the

blade receptacle (3) so that it

faces the carburetor

: Push the blade receptacle (3)

completely onto the connector

tab (arrow)

– Reassemble remaining parts in

reverse order

100

2410RA380 TG2410RA381 TG

153MS 241 C

14.1.3 Thermostatic switch

The thermostatic switch is an

electronic component that cannot

be tested directly. The functionality

of the thermostatic switch can be

determined using the

troubleshooting chart, b 14.2

– Remove the carburetor, b 13.5

: Remove screw (1)

: Remove thermostatic switch (2)

: Hold end cover (3) so that the

pump membrane and gasket

remain secured

2410RA362 TG

Installation

– Check that the pump diaphragm

and gasket are correctly seated

: Hold end cover (1) so that the

pump membrane and gasket

remain secured

: Position the thermostatic

switch (2) so that it rests against

the raised part (arrow)

: Screw in the screw (3) and

tighten it

2410RA364 TG

: Press lead (1) into the

guides (arrows) so that is is

behind the peg (2)

: Slide on the insulating tube (3)

– Install the carburetor, b 13.5

– Press the plug connection

together completely, b 1

– Reassemble remaining parts in

reverse order

– Check correct functioning

2410RA374 TG

1 32

154 MS 241 C

14.2 Troubleshooting, carburetor heating

Heating element resistance

Measure when

temperature = +20 °C (68 °F)

Replace thermostatic

switch, b 14.1.3

Replace heating

element, b 14.1.2

Carburetor heating element

OK?

yes

G = Generator

1 = Rear handle

2 = Front handle

3 = Heating switch

4 = Thermostatic switch

5 = Heating element (carburetor

heating)

0001RA505 TG

1 4

Resistance

approx. 12 Ω?

Circuit diagram

155MS 241 C

14.3 Handle heating systems

14.3.1 Troubleshooting

The entire handle heating system is

maintenance-free and not subject to

electrical wear. Faults in the

generator, heating elements and

leads are generally caused by

mechanical damage.

Failures in the heating system may

be due to two reasons:

1. Interruption in the

electrical circuit due to

damage to leads or

components.

2. Short circuit in electrical circuit

due to insulation damage.

– Remove handle molding, b 11.2

: Pull one of the plug connections

out of the guide and slide

insulating tube (1) towards wiring

harness

: Disconnect plug connection (1)

2410RA401 TG

2410RA402 TG

: Set heating switch (1) to position

"F"

– Set ohmmeter to "Ω" position

– Move the Master Control lever to

position "

: Clip test leads onto the lead from

the wiring harness and the lead

from the heating element

Carburetor heating

– Disconnect plug connection to

thermostatic switch, then reinstall

carburetor, filter base and baffle,

b 13.5

All electrical components of the

handle heating system are

connected in series with the

ohmmeter.

If the system is OK, the ohmmeter

will show a reading of approx. 10 Ω

in the measuring range "Ω".

2410RA382 TG

100

2410RA403 TG

If the pointer does not move, there

is a break in the circuit.

If the ohmmeter shows a very low

value, there is a short circuit in one

of the components.

In both cases, each component

must be checked individually,

In the process, the generator

connector remains disconnected

from the thermostatic switch

connector.

– Test according to the

troubleshooting chart, handle

heating and generator, b 14.7.1

– Measure resistance in front

handle, b 14.6

– Measure resistance in rear

handle, b 14.5

– Press the plug connection

together completely, b 1

– After testing, reconnect the leads

and slide the protective tube back

over the plug connection.

– Reassemble remaining parts in

reverse order

156 MS 241 C

14.4 Heating switch

– Remove filter base, b 13.3

: Remove blade receptacle (1)

: Remove contact sleeve (2)

: Unscrew nut (1)

: Remove washer (2)

: Pull heating switch (1) off to the

inside and examine, replace if

necessary

2410RA383 TG

2410RA384 TG

2410RA385 TG

: Remove screw (1)

: Remove socket terminal (2) at

the holder (4) and remove

ground wire (3) from the

guide (arrow)

: Check holder (4), if necessary,

remove from the air guide shroud

and replace

: Disconnect the ground wire (1)

from the socket terminal (2)

– Check the individual parts and

replace if necessary

2410RA386 TG

2410RA500 TG

Installation

: Push blade receptacle (1) onto

the straight connector tag of the

socket terminal (2) so that the

crimped side faces the angled

connector tag (3)

: Press holder (1) as far as it will go

into the guides (arrows) of the air

guide shroud

2410RA501 TG

2410RA502 TG

157MS 241 C

: Orient socket terminal of the

ground wire so that the connector

tab (1) points toward the

carburetor and the flat

faces (arrows) engage between

the fins (2) of the holder

– Position socket terminal at the

holder

: To ensure correct switch position,

orient the heating switch (1) so

that the groove faces the

pin (arrow)

: Push the heating switch (1)

through the contact ring of the

ground wire into the hole of the

holder (2)

2410RA387 TG

2410RA388 TG

: Fit washer (1)

: Tightly screw on nuts (2)

: Position ground wire (1) so that

the crimped side (arrow) of the

cable lug faces upward

: Screw in the screw (2) and

tighten it

– Checking correct functioning

: Press ground wire (1) as far as it

will go into the guide (arrow)

2410RA389 TG

2410RA390 TG

2410RA391 TG

: Push the contact sleeve (1) into

the heating switch (2) as far as it

will go

: Press lead (1) into the

guides (arrows)

: Push on blade receptacle (1) so

that the crimped side faces the

carburetor

– Reassemble remaining parts in

reverse order

2410RA392 TG

1 2

2410RA393 TG

2410RA394 TG

158 MS 241 C

14.5 Heating element in

handle

– Remove the handle molding and

trigger interlock, b 11.2

: Pull insulating tubes (1) and (2)

with plug connections out of the

guides

: Slide insulating tubes (1) towards

connecting leads and disconnect

plug connections

: Check heating element (1) and

replace if necessary

2410RA395 TG

2410RA396 TG

100

2410RA405 TG

If the heating element is intact, the

ohmmeter will indicate a value

of approx. 1.6 Ω

(reading 1.5...2.0 Ω) in the

measuring range "Ω".

The heating element must be

replaced if the value is outside this

range.

Is the heating element inoperable

despite a successful resistance

measurement?

– Test generator and heating

switch, b 14.3, b 14.7

– Remove and examine

connecting leads, replace if

necessary, b 14.9

Installation

: Position new heating element (1)

so that it rests against the

edge (arrow) of the handle –

make certain that the heating

element is inserted completely

An incompletely inserted heating

element cannot transfer the heat

completely to the handle – danger

of overheating of the heating

element.

– Press the plug connections

together completely, b 1

5902RA595 TG

The connecting leads must be

routed so that the thin lead runs

underneath the thick lead.

The heating element leads must not

cross one another.

: Push connectors and socket

terminals together

: Slide insulating tubes (1) over the

plug connections

: Press insulating tubes (1) and (2)

with plug connections into the

guides (arrows)

2410RA396 TG

2410RA398 TG

159MS 241 C

The black lead of the handle heating

must be routed underneath the gray

lead of the wiring harness.

: Press the leads of the handle

heating and the wiring harness

into the guide (arrows)

– Reassemble remaining parts in

reverse order

14.6 Heating element in front

handle

The heating element in the front

handle cannot be replaced. In case

of damage, the complete front

handle must be replaced.

Check heating element

– Remove the handle molding,

b 11.2

The functioning of the heating

element in the front handle can be

checked simply using the following

test procedure.

– Disconnect the plug connections

of the heating element at the

handle

Carry out measurement between

the two socket terminals and the

contact sleeve.

– Set heating switch to F

2410RA399 TG

: Clip one test lead to the terminal

socket (1) of the thick connecting

lead and the second to the

contact sleeve of the heating

switch

If the heating element is intact, the

ohmmeter will indicate a value

of approx. 6.4 Ω

(reading 6.0...8.0 Ω) in the

measuring range "Ω".

If the reading obtained is outside

this tolerance, then the front

handle (front handle heating

element) must be checked directly

at the connecting leads.

– Disconnect plug connections at

the front handle, b 10.4.1

: Clip test leads to the

connectors of the leads (1)

and (2)

If the heating element is intact, the

ohmmeter will indicate a value

of approx. 6.4 Ω

(reading 6.0...8.0 Ω) in the

measuring range "Ω".

100

2410RA400 TG

2410RA404 TG

If the reading obtained is outside

this tolerance, then the front

handle (front handle heating

element) must be replaced,

b 10.4.1.

Is the heating element inoperable

despite a successful resistance

measurement?

– Remove and examine

connecting lead to front handle

heating element, replace if

necessary, b 14.9

– Examine wiring harness, replace

if necessary, b 14.3, b 14.8

– Test generator and heating

switch, replace if necessary,

b 14.7, b 14.4

– Reassemble parts in reverse

order

160 MS 241 C

14.7 Generator

– Remove the control unit, b 7.3

– Remove the flywheel, b 7.6

– Remove the pre-separator,

b 7.2

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4.2

: Remove grommet (1) and

generator lead (2) from the

guide (arrow)

: Remove screws (1)

: Remove generator (2) and pull

the lead (3) out of the

guides (arrows)

: Pull lead (3) out of the opening of

the crankcase

2410RA406 TG

2410RA407 TG

: Check generator and

poles (arrow) for cracks or other

damage. Replace generator if

necessary.

: Check magnet ring (arrow) in

flywheel for cracks or other

damage. Replace flywheel if

necessary.

0001RA448 TG0001RA449 TG

Installation

– Press the plug connection

together completely, b 1

: Fit generator (1) with connecting

lead (arrow) facing the housing

– Check that the generator is

seated correctly

– Insert and tighten down the

screws

: Push terminal socket (1) of the

generator lead through the

opening (arrow)

2410RA408 TG

2410RA409 TG

161MS 241 C

: Lay generator lead (1) in bottom

of recess (arrow)

: Press generator lead (1) into the

guides (arrows) so that it runs

snug against the crankcase

: Pull the generator lead (1)

through the opening (arrow) until

it lies snug against the crankcase

2410RA410 TG

2410RA411 TG

2410RA412 TG

: Press generator lead (1) on the

inside of the crankcase into the

guide (arrow) so that it lies snug

: Push grommet (1) onto the

generator lead (2) so that the

cone (arrow) faces the generator

– Install air guide shroud, b 13.4.2

2410RA413 TG

2410RA414 TG

The lead (1) must be seated

completely in the recess (arrow).

The flywheel must not touch the

generator lead

– power supply can be interrupted.

– Reassemble remaining parts in

reverse order

2410RA415 TG

162 MS 241 C

14.7.1 Troubleshooting chart, handle heating systems and generator

Check generator

Resistance between engine ground

and generator connection

approx. 0.5–1 Ω?

Start

Do both handles become

warm?

Measure resistance of the individual

heating elements using

ohmmeter

Disconnect plug connection to

thermostatic switch

b 13.5

yes

Activate

switch

yes

Resistance of

handle heating element

approx. 1.6 Ω?

Check rear handle heating element:

in good condition?

Is it completely against the

handle housing?

Heating switch

set to „F“?

Replace

handle heating

element,

b 14.5

Replace

generator,

b 14.7

yes

163MS 241 C

System OK

Disconnect and clear plug connections to

front handle heating element,

b 10.4.1

check handle heating

element

resistance approx. 6.4 Ω?

Test heating switch

(contact sleeve against switch housing)

Closed: approx. 0 Ω ?

Open: no continuity,

b 14.3

Reassemble plug connection

to thermostatic switch,

b 13.5

Replace

front handle,

b 10.4.1

Replace

heating switch,

b 14.4

yes

164 MS 241 C

14.7.2 Summary of test connections and test values

– The wires in the handle must be

unplugged to test the individual

components separately

Pull wire out for this purpose

Component Ohmmeter

connection (either test

lead can be used)

Resistance Ω If faulty

Lead 1 Lead 2 Re-

quired

Actual Cause Remedy

Switch Switch

connection

Switch

housing

< 0.5 - Switch faulty Replace switch

Heating element in

handle

Connector

to lead

from

heating

element

Connector

to lead

from

heating

element

1.6 1.5 - 2.0 Heating element

- Break in wire,

heating element

damaged

Replace heating

element and/or

repair insulation

0 Short circuit due to

damaged insulation

Heating element in

front handle

Connector

to lead

from front

handle

heating

element

Connector

to lead

from front

handle

heating

element

6.4 6.0...8.0 Heating element

- Break in wire,

heating element

damaged

Replace front

handle

0 Short circuit due to

damaged insulation

repair insulation

165MS 241 C

Circuit diagram

Component Ohmmeter

connection (either test

lead can be used)

Resistance Ω If faulty

Lead 1 Lead 2 Re-

quired

Actual Cause Remedy

Generator Connector

generator

lead

Weight 0.6 0.5 - 1 Generator OK

- Break in wire,

generator damaged

Replace generator

0 Short circuit due to

damaged insulation

Repair insulation

G = Generator

1 = Rear handle

2 = Front handle

3 = Heating switch

4 = Thermostatic switch

5 = Heating element (carburetor

heating)

0001RA505 TG

1 4

166 MS 241 C

14.8 Wiring harness

If the wiring harness if faulty, it must

be replaced.

– Remove shroud, b 6.4

– Remove the handle molding and

trigger interlock, b 11.2

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

– Remove the air guide shroud,

b 13.4.2

– Lower the tank housing and

remove the cover of the plug

connections, b 10.4.1

: Pull plug connections (1) and (2)

with insulating tubes out of the

guides (arrows)

: Push insulating tube (1) and (2)

toward the wiring harness

2410RA417 TG

2410RA418 TG

: Disconnect plug connections and

remove wiring harness (3)

Installation

– Press the plug connections

together completely, b 1

: Push insulating tubes (1) onto

the wires with the socket

terminal (2) and (3)

Grommet (4) must rest against the

protective tube (5).

: Press plug (1) of handle into the

terminal socket (2) of thick wire

as far as it will go

: Slide on the insulating tube (3)

2410RA419 TG

2410RA420 TG

2 1

The wires of the handle must be

seated completely in the

guide (arrow).

: Press the plug (1) of the thin

connecting wire (2) into the

terminal socket (3) of the wiring

harness (4) as far as it will go

: Slide on the insulating tube (5)

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

2410RA421 TG2410RA422 TG

1 32

2410RA423 TG

167MS 241 C

: Run the thin wire (1) with a

loop (arrow) around the fin and

press it into the guide as far as it

will go

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

– Install cover over the plug

connections, lift and fasten tank

housing, b 10.4.1

– Install air guide shroud, b 13.4.2

– Reassemble remaining parts in

reverse order

2410RA424 TG

2410RA425 TG

14.9 Connecting leads heating

elements

In the absence of a fault in the wiring

harness, heating elements,

generator or heating switch, then

the problem may also be due to

damaged connecting leads

between the front and rear handle

heating elements.

– Remove shroud, b 6.4

– Remove handle molding, trigger

interlock and throttle trigger,

b 11.2

– Lower the tank housing and

remove the cover of the plug

connections, b 10.4.1

: Pull connecting lines (1) and (2)

out of the guide (arrows)

: Pull plug connections (1), (2)

and (3) with insulating tubes out

of the guides

2410RA430 TG

2410RA428 TG

: Push insulating tubes (1) toward

connecting leads and disconnect

plug connections (2) and (3)

Do not disconnect plug

connection (4) with insulating tube.

: Pull plug connections (1) and (2)

with insulating tubes out of the

guides (arrows)

2410RA429 TG

1 4

2410RA431 TG

168 MS 241 C

: Slide insulating tubes (1) towards

connecting leads and disconnect

plug connections

– Remove and examine

connecting leads, replace if

necessary

Installation

– Press the plug connection

together completely, b 1

Run all leads under the throttle rod.

: Push insulating tubes (1) onto

both ends of the connecting

leads (2) and (3)

2410RA432 TG

2410RA433 TG

2 1

: Connect the thin connecting

lead (1) with the thin lead (2) of

the wiring harness and the lower

lead (3) of the handle heating

element

– Push connectors and socket

terminals together as far as

possible

: Slide insulating tubes (4) over the

plug connections

: Connect the thick connecting

lead (1) with the long lead (2) of

the handlebar and the upper

lead (3) of the handle heating

element

– Push connectors and socket

terminals together as far as

possible

: Slide insulating tubes (4) over the

plug connections

At the handlebar, the long lead must

be run under the shorter lead.

2410RA434 TG

2410RA435 TG

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

: Run the thin wire (1) with a

loop (arrow) around the fin and

press it into the guide as far as it

will go

2410RA436 TG

2410RA437 TG

2410RA438 TG

169MS 241 C

: Position insulating tube (1) with

plug connection at the edge of

the tank housing and push it into

the guide (arrow) as far as it will

: Orient cover (1) so that the

pegs (2) engage the holes and

the tab (3) engages the

fin (arrows)

– Replace cover, insert and tighten

screw

– Ensure that wires are not

pinched

2410RA439 TG

2410RA440 TG

The thin connecting lead must be

run underneath the thick connecting

lead.

: Starting at the cover (1) of the

plug connections, route the leads

and press them into the

guide (arrow)

: Press plug connection (2) of the

thin connecting lead into the right

guide and plug connection (3) of

the thick connecting lead into the

left guide of the handle

– Reassemble remaining parts in

reverse order

2410RA441 TG

170 MS 241 C

15. Special tools

New special tools

Existing special tools

No. Designation Part No. Use Re-

marks

1 Press sleeve 1143 893 2400 Pressing in oil seal

(Ignition side)

2 Wiring tool 5910 890 4000 Inserting wires in the guides

No. Designation Part No. Use Re-

marks

1 Carburetor and crankcase tester 0000 850 1300 Testing crankshaft in engine and

carburetor for leakage

- Connector 0000 855 9200 Testing carburetor for leaks

- Hose for leakage test 1110 141 8600 Testing carburetor for leaks

- Plug for leakage testing 1122 025 2200 Testing decompression valve for leaks

2 Sealing plate 0000 855 8106 Testing crankshaft in engine and

carburetor for leakage

3 Installing tool 0000 890 2201 Installation of starter rope guide

bushing

4 Clamping strap 0000 893 2600 Tension the piston rings

5 Locking strip 0000 893 5904 Blocking crankshaft

6 Bit T 27 x 125 0812 542 2104 Removing and installing spline socket

head screws with electric or pneumatic

screwdrivers; tightening down screws

with torque wrench

7 Wooden assembly block 1108 893 4800 Positioning piston/lowering tank

housing maintaining spacing

8 Assembly drift 1110 893 4700 Removing and installing piston pins

9 Setting gauge 1111 890 6400 Setting air gap between control unit

and flywheel

10 Installing tool 1116 893 4800 Installing rewind spring

11 Assembly tube 1117 890 0900 Hook in clutch spring

12 Flange 1118 850 4200 Leakage test

13 Press sleeve 1118 893 2401 Pressing in oil seal

(Clutch side)

14 Combination wrench 1129 890 3401 Spark plug 1)

15 Installing sleeve 1141 893 4600 Protection of the oil seal

(Ignition side/clutch side)

171MS 241 C

No. Designation Part No. Use Re-

marks

16 Service tool ZS

including

Washer 5910 893 2103

5910 007 2201 Removal and installation of

crankshaft (clutch side)

– Washer

in supplementation to service tool

kit ZS 5910 007 2200

5910 893 2103 Pulling together the crankcase

- Screw sleeve 5910 893 2420 Installing crankshaft

17 Service tool kit AS 5910 007 2205 Removal and installation of

crankshaft (clutch side)

- Screw sleeve 5910 893 2409 Pulling together the crankcase

18 Test lead 5910 840 0903 M-Tronic diagnostic and testing tasks

19 Clamping strip for assembly

stand

5910 850 1650 Clamp machine to assembly stand

20 ZAT 4 ignition tester 5910 850 4503 Test ignition system

21 ZAT 3 ignition tester 5910 850 4520 Test ignition system

22 Flange 5910 855 4201 Sealing the cylinder exhaust port for

leakage test

23 Torque wrench 5910 890 0302 Screw connections (0.5 to 18 Nm)

24 Torque wrench 5910 890 0312 Screw connections (6 to 80 Nm)

25 Installing tool 10 5910 890 2210 Fit hookless snap rings in piston

- Sleeve 5910 893 1707 Sleeve for installing tool 10

26 Bit T 27 x 150 5910 890 2400 IS-P screws

27 Assembly hook 5910 890 2800 Detach springs from clutch shoes

28 Assembly stand 5910 890 3101 Holding chain saw for servicing /

repairs

29 Puller 5910 890 4400 Extracting the oil seal

- Jaws (with profile no. 6) 0000 893 3711 Extracting the oil seal

30 Puller 5910 890 4504 Removing flywheel

31 Stud puller, M8 5910 893 0501 Removing rail mounting studs

32 Assembly hook 5910 893 8800 Remove pick-up body

33 Installing tool 5910 893 9600 Removing and installing collar nuts on

chain sprocket cover

Remarks:

1) Use only for releasing.

172 MS 241 C

16. Service accessories

No. Designation Part No. Use

1 STIHL multi-purpose grease 0781 120 1109

2 Grease (225 g tube) 0781 120 1111 Oil seals, sliding and bearing points

3 STIHL special lubricant 0781 417 1315 Bearing bore in rope rotor, rewind spring in fan

housing

4 STIHL press fluid OH 723 0781 957 9000 Rubber elements antivibration elements

5 Medium-strength thread-locking

adhesive (Loctite 242)

0786 111 2101

6 Standard solvent-based

degreasant not containing any

chlorinated or halogenated

hydrocarbons

Cleaning mating surfaces and the carburetor,

cleaning the crankshaft stub and tapers in

flywheel

englisch / english

0455 741 0123. M0,7. A11. DDS. Printed in Germany

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Stihl MS 241 C-M Manual

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