Stihl 4137 Series, Manual, Page: 41 / 58

40 Series 4137 Components - HT
Adjusting idle speed
– Carry out the standard setting.
Engine stops while idling
:
Turn the idle speed screw LA (1)
VA
936RA446
L A
L
1
clockwise until the chain begins
to run, then turn the screw back
half a turn from that position.
Chain rotates when engine is
idling
– Carry out the standard setting.
– Turn the idle speed screw LA (1)
counterclockwise until the chain
stops running, then turn the
screw another half turn in the
same direction.
The carburetor is tuned at the
factory so that the engine receives
an optimum fuel-air mixture under
all operating conditions.
Standard setting
– Check chain tension and adjust if
necessary.
– Clean or replace the air filter,
b
9.1
– Clean the spark arresting screen,
replace if necessary,
b
5.4
:
Carefully turn the idle speed
screw (
LD ) counterclockwise
down onto its seat. Then open it
two full turns clockwise.
Adjusting idle speed
– Carry out the standard setting.
936RA440
VA
Adjusting idle speed
– Carry out standard setting.
– Start the engine and allow it to
warm up.
Engine stops while idling
– Turn the idle speed screw ( LD )
slowly clockwise until the engine
runs smoothly. The chain must
not rotate.
Chain rotates when engine is
idling
– Turn the idle speed screw ( LD )
counterclockwise until the chain
stops running, then turn the
screw about another one turn in
the same direction.
Erratic idling behavior, poor
acceleration
– Turn the idle speed screw ( LD )
slowly no more than half a turn
counterclockwise.
9.4.2 Carburetor with
LD Screw