Operation Manual

31HT 250
English / USA
Adjusting Idle Speed
It is usually necessary to change the
setting of the idle speed screw (LA)
after every correction to the low speed
screw (L).
: Warm up the engine.
Engine stops while idling
: Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the chain must not
run.
Chain runs when engine is idling
: Turn the idle speed screw (LA)
slowly counterclockwise until the
chain stops running – then turn the
screw another
1
/
2
to 1 turn in the
same direction.
Erratic idling behavior, engine stops
even though setting of LA screw is
correct, poor acceleration
Idle setting too lean:
: Turn low speed screw (L)
counterclockwise (about
1
/
4
turn)
until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting too rich:
: Turn low speed screw (L) clockwise
(about
1
/
4
turn) until the engine runs
and accelerates smoothly.
Wrong fuel mix (too much engine oil in
the gasoline), a dirty air filter and
unfavorable running conditions (mostly
at part throttle etc.) affect the condition of
the spark plug. These factors cause
deposits to form on the insulator nose
which may result in trouble in operation.
Checking the Spark Plug
000BA002 KN