English
Spark Plug
If the engine is down on power,
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difficult to start or runs poorly at idle
speed, first check the spark plug.
Fit a new spark plug after about 100
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operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the Spark Plug
Depress throttle trigger lockout and
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throttle trigger at the same time and
move the Master Control lever to
choke closed l.
Turn the knob 90° to the left.
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Lift off the carburetor box cover
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vertically.
34
4
3
Place fingers behind the air filter (3),
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press thumbs against the housing,
swing the filter in the direction of the
rear handle and remove it.
Remove the shutter (4).
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Pull off the spark plug boot.
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Unscrew the spark plug.
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Checking the Spark Plug
Clean dirty spark plug.
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Check electrode gap (A) and
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readjust if necessary – see
"Specifications".
Rectify the problems which have
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caused fouling of the spark plug.
Possible causes are:
Too much oil in fuel mix.
–
Dirty air filter.
–
Unfavorable running conditions.
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WARNING
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 injuries or
damage to property.
A
1
MS 250