Spark Plug - Stihl FS 45 Instruction Manual

13 Spark Plug

► Start and warm up the engine.
12.4.1 Engine stops while idling
► Turn the idle speed screw (LA) slowly clock‐
wise until the engine runs smoothly – the cut‐
ting attachment must not rotate.
12.4.2 Cutting attachment rotates when
engine is idling
► Turn the idle speed screw (LA) counterclock‐
wise until the cutting attachment stops moving
and then turn the screw another 1/2 to 1 full
turn in the same direction.
WARNING
If the cutting attachment continues to rotate
when the engine is idling, have your machine
checked and repaired by your servicing dealer.
12.4.3 Erratic idling behavior, poor accelera‐
tion (even though setting of LA screw
is correct).
Idle setting is too lean
► Rotate the low speed screw (L) slowly
about 1/4 turn counterclockwise until the
engine runs smoothly and still accelerates sat‐
isfactorily.
12.4.4 Erratic idling behavior
Idle setting is too rich
► Rotate the low speed screw (L) slowly
about 1/4 turn clockwise until the engine runs
smoothly and still accelerates satisfactorily.
It is usually necessary to change the setting of
the idle speed screw (LA) after every correction
to the low speed screw (L).
12.5 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 more than a 3/4 turn.
0458-232-0121-F
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.
13 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".
13.1 Removing the Spark Plug
► Move the stop switch to 0.
► Pull off the spark plug boot (1).
► Unscrew the spark plug.
13.2 Checking the Spark Plug
► 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.
English
1
A
19