15 TUNING THE ENGINE
100
15.5 Carburetor – adjusting the idle speed
V01037-10
–
Screw in idle air adjusting screw
1
all the way and turn it to
the specified basic position.
Guideline
Idle air adjusting screw
open 2 turns
– Run the engine until warm.
Guideline
Warm-up time ≥ 5 min
Danger
Danger of poisoning Exhaust gases are toxic and
inhaling them may result in unconsciousness and
death.
– Always make sure there is sufficient ventilation
when running the engine.
– Use an effective exhaust extraction system when
starting or running the engine in an enclosed
space.
–
Adjust the idle speed with adjusting screw
2
.
Guideline
Choke function deactivated – The choke lever is pushed in
to the stop. ( p. 18)
Idle speed 1,400 … 1,500 rpm
–
Turn idle air adjusting screw
1
slowly in a clockwise direc-
tion until the idle speed begins to fall.
– Note the position and turn the idle air adjusting screw slowly
counterclockwise until the idle speed again begins to fall.
– Adjust to the point between these two positions with the
highest idle speed.
Info
If there is a big engine speed rise, reduce the idle
speed to a normal level and repeat the above steps.
If the procedure described here does not lead to sat-
isfactory results, the cause may be a wrongly dimen-
sioned idling jet.
If you can turn the idle air adjusting screw to the end
without any change of engine speed, mount a smaller
idling jet.
After changing the idling jet, start from the beginning
with the adjusting steps.
Following extreme air temperature or altitude changes,
adjust the idle speed again.
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