Manual Stihl MS 241 C-M (page 170 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

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

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Stihl MS 241 C-M Manual

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