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21 Spark Plug
► Turn the low speed screw (L) slowly counter‐
clockwise until the engine runs and acceler‐
ates smoothly.
It is usually necessary to change the setting of
the idle speed screw (LA) after every correction
to the low speed screw (L).
20.4
Fine Tuning for Operation at
High Altitude
A slight correction of the setting may be neces‐
sary if the engine does not run satisfactorily:
► Carry out 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.
21 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".
21.1
Removing the Spark Plug
► Set the Master Control lever (1) to F
0458-567-0121-B
1
► Loosen the twist lock (2) in the direction of the
arrow.
► Remove the carburetor box cover (3).
► Pull off the spark plug boot.
► Unscrew the spark plug.
21.2
Checking the Spark Plug
► Clean dirty spark plug.
English
3
2
A
29
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