It is usually necessary to change the setting of
the idle speed screw (LA) after every correction
to the low speed screw (L).
23.3.4
Fine Tuning for Operation at High Alti‐
tude
A slight correction of the setting may be neces‐
sary if engine does not run satisfactorily:
► Carry out the standard setting.
► Warm up the engine.
► Turn high speed screw (H) slightly clockwise
(leaner) – no further than stop.
NOTICE
After returning from high altitude, reset the car‐
buretor to the standard setting.
If the setting is too lean there is a risk of engine
damage due to insufficient lubrication and over‐
heating.
24 Spark Plug
► If the engine is down on power, difficult to start
or runs poorly at idle speed, first check the
spark plug.
► Fit a new spark plug after about 100 operating
hours – or sooner if the electrodes are badly
eroded. Install only suppressed spark plugs of
the type approved by STIHL – see "Specifica‐
tions".
24.1
Remove the spark plug
► Move the Master Control lever to the stop
position 0
137BA008 KN
► Turn the knob above the rear handle in the
direction of the arrow and remove the carbu‐
retor box cover
171BA024 KN
► Pull off the spark plug boot
► Unscrew spark plug
24.2
Checking the Spark Plug
000BA039 KN
A
► Clean dirty spark plug.
► Check electrode gap (A) and readjust if neces‐
sary – see "Specifications".
► Rectify the problems which have caused foul‐
ing of the spark plug.
Possible causes are:
–
Too much oil in fuel mix.
–
Dirty air filter.
–
Unfavorable running conditions.
1
000BA045 KN
24 Spark Plug
English
0458-550-0121-B
31