Engine Running Behavior - Stihl KA 120 Instruction Manual

English
► 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".
14.1 Removing the Spark Plug
► Turn off the engine.
► Pull off the spark plug boot (1).
► Unscrew the spark plug.
14.2 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.
– Dirty air filter.
– Unfavorable running conditions.
16
Arcing may occur if the adapter nut (1) is loose
or missing. Working in an easily combustible or
explosive atmosphere may cause a fire or an
explosion. This can result result in serious inju‐
ries or damage to property.
► Use resistor type spark plugs with a properly
tightened adapter nut.
14.3
A
► Screw the spark plug (2) into the cylinder and
fit the boot (1) (press it down firmly).

15 Engine Running Behavior

If engine running behavior is unsatisfactory even
though the air filter is clean and the carburetor
and throttle cable are properly adjusted, the
cause may be the muffler.
Have the muffler checked by a servicing dealer
for contamination (carbonization).
STIHL recommends that you have servicing and
1
repair work carried out exclusively by an author‐
ized STIHL servicing dealer.
15 Engine Running Behavior
WARNING
Installing the Spark Plug
1
2
0458-516-0121-B