Spark Arresting Screen In Muffler - Stihl SR 420 Instruction Manual

English
Adjusting Idle Speed
Carry out the standard setting.
N
Start and warm up the engine.
N
L
Engine stops while idling
Turn the idle speed screw (LA)
N
slowly clockwise until the engine
runs smoothly.
Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
Turn the low speed screw (L)
N
counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
Turn the low speed screw (L)
N
clockwise, no further than stop, until
the engine runs and accelerates
smoothly.
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
20
Fine Tuning for Operation at High
Altitude
A slight correction of the setting may be
necessary if engine does not run
satisfactorily:
Carry out the standard setting.
N
Warm up the engine.
N
Turn high speed screw (H) slightly
N
clockwise (leaner) – no further than
stop.
LA
NOTICE
After returning from high altitude, reset
the carburetor to the standard setting.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
Spark Arresting Screen in
Muffler
1
If the engine is down on power or does
not run smoothly at maximum RPM,
check the spark arresting screen (not
fitted in all versions) in the muffler.
WARNING
Wait for the engine to cool down
completely before performing this work.
Use suitable tool to squeeze ends of
N
clip (1) together and then lift the clip
away.
Pull the spark arresting screen (2)
N
out of the muffler.
Clean the spark arresting screen if
N
necessary.
If the spark arresting screen is
N
damaged or heavily carbonized, fit a
new one.
2
SR 420