Spark Plug - Stihl MS 250 Instruction Manual

English

Spark Plug

If engine is down on power, difficult to
start or runs poorly at idling speed, first
check the spark plug.
Fit a new spark plug after approx. 100
operating hours or earlier if the
electrodes are badly eroded.
Wrong fuel mix (too much engine oil in
the gasoline), a dirty air filter and
unfavorable running conditions (mostly
at part throttle etc.) affect the condition
of the spark plug. These factors cause
deposits to form on the insulator nose
which may result in trouble in operation.
Removing the Spark Plug
Depress throttle trigger lockout and
N
throttle trigger at the same time and
move the Master Control lever to
choke closed l.
Turn the knob 90° to the left.
N
Lift off the carburetor box cover
N
vertically.
42
4
3
Place fingers behind the air filter (3),
N
press thumbs against the housing,
swing the filter in the direction of the
rear handle and remove it.
Remove the shutter (4).
N
Pull off the spark plug boot.
N
Unscrew the spark plug.
N
Checking the Spark Plug
Clean dirty spark plug.
N
Check electrode gap (A) and
N
readjust if necessary – see
"Specifications."
Use only resistor type spark plugs of
N
the approved range.
Rectify problems that have caused
fouling of spark plug:
too much oil in fuel mix,
–
dirty air filter,
–
unfavorable running conditions, e.g.
–
operating at part load.
A
MS 250