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Opening up B
Engine behavior when the throttle opens. The idle jet and the shape of the
throttle valve influences this range. If, despite good idling-speed and part-
throttle setting, the engine sputters and smokes when the throttle is fully
opened and develops its full power not smoothly but suddenly at high
engine speeds, the mixture to the carburetor will be too rich, the fuel level
too high or the float needle is leaking.
Part-throttle range C
Operation with partly open throttle valve. This range is only influenced by
the jet needle (shape and position). The optimum part-throttle setting is
controlled by the idling setting in the lower range and by the main jet in the
upper range. If the engine runs on a four-stroke cycle or with reduced
power when it is accelerated with the throttle partly open, the jet needle
must be lowered by one notch. If then the engine pings, especially when
accelerating under full power at maximum engine revs, the jet needle
should be raised.
If these faults should occur at the lower end of the part throttle range at a
four-stroke running, make the idling range leaner; if the engine pings,
adjust the idling range richer.
Full throttle range D
Operation with the throttle fully open (flat out). This range is influenced by
the main jet and the jet needle. If the porcelain of the new spark plug is
found to have a very bright or white coating or if the engine rings, after a
short distance of riding flat out, a larger main jet is required. If the porce-
lain is dark brown or black with soot the main jet must be replaced by a
smaller one.
Draining the float chamber of the carburetor
Following every wet-cleaning procedure, the float chamber of the carbure-
tor should be drained in order to remove any water that may have penetra-
ted into it. Water in the float chamber leads to engine malfunction.
Make sure you do this while the engine is cold. Close the fuel tap, and place
a cloth under the carburetor, which is capable of absorbing the leaking fuel.
Unscrew the plug
1 and clean it with compressed air. Then, mount the
plug together with the gasket, open the fuel tap, and check the float
chamber for leaks.
WARNING
FUEL IS EASILY FLAMMABLE AND TOXIC. WHEN HANDLING FUEL, BE SURE TO EXERCISE
THE UTMOST CAUTION
. NEVER PERFORM ANY WORK ON THE FUEL SYSTEM NEAR OPEN
FLAMES OR BURNING CIGARETTES
. ALWAYS ALLOW THE ENGINE TO COOL OFF FIRST.
I
MMEDIATELY CLEAN UP ANY FUEL WHICH MAY HAVE BEEN SPILLED. MATERIALS SATURA-
TED WITH FUEL ARE ALSO EASILY FLAMMABLE. IN CASE YOU INGESTED FUEL OR FUEL
SPLASHED INTO YOUR EYES
, CONSULT A DOCTOR IMMEDIATELY.
D
ISPOSE OF THE FUEL PROPERLY.
Checking the float level *
Arrange the carburetor diagonally at about 60° so that the spring in the
float needle valve is not pressed together. In this position, the edge of
the
float should be parallel with the float chamber sealing surface (see
illustration).
NOZD
NOZE
NOZF
NOZG
NOZH
JET NEEDLE
RANGE OF ACTION
TYPE RICHER LEANER
