Spark Plug - Stihl MS 250C Instruction Manual

Spark Plug

If there is a loss of engine power, the
machine is difficult to start or runs poorly
at idle, first check the spark plug.
Install a new spark plug after approx.
100 operating hours or earlier if the
electrodes are eroded/corroded.
The 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 degrade performance.
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.
MS 250
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 the spark plug if it is dirty
N
Check the electrode gap (A) and
N
readjust if necessary – see
"Specifications"
Use only resistor type spark plugs of
N
the approved range. See the
chapter "Specifications" in this
instruction manual
Correct the problems that have caused
fouling of the spark plug:
too much oil in fuel mix;
–
dirty air filter; or
–
unfavorable running conditions, e.g.
–
operating at part throttle.
English
A
45