Spark Arresting Screen In Muffler; Spark Plug - Stihl FS 91 Manual De Instrucciones

Spark Arresting Screen in
Muffler
If the engine is down on power,
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check the spark arresting screen in
the muffler.
Wait for the muffler to cool down.
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4
5
Take out the screw (4).
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Lift the spark arresting screen (5)
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and pull it out.
Clean the spark arresting
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screen (5). If the screen is damaged
or heavily carbonized, install a new
one.
Refit the spark arresting screen (5).
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Insert the screw (4) and tighten it
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down firmly.
FS 91, FS 91 R

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
approximately 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
1
2
3
Remove the cover (1).
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Pull off the spark plug boot (2).
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Unscrew the spark plug (3).
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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 chapter
"Specifications."
Use only resistor type spark plugs of
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the approved range.
Rectify problems which have caused
fouling of spark plug:
too much oil in fuel mix,
–
dirty air filter,
–
unfavorable running conditions, e.g.
–
operating at part load.
English
A
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