MS 311, MS 391
English
30
N
If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N
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
"Specifications".
Remove the spark plug
N
Move the Master Control lever to the
stop position
0
N
Push the hand guard forwards – the
saw chain is blocked
N
Loosen screws (1)
N
Remove the shroud (2)
N
Pull off the spark plug boot
N
Unscrew spark plug
Checking the spark plug
N
Clean dirty spark plug.
N
Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N
Rectify the problems which have
caused fouling of the spark plug.
Possible causes are:
–
Too much oil in fuel mix.
–
Dirty air filter.
–
Unfavorable running conditions.
Install spark plug
N
Screw in the spark plug and press
on the spark plug boot
N
Refit the shroud and tighten the
screws
Spark Plug
1
4903BA002 KN
1
1
2
4903BA007 KN
000BA039 KN
A
If the spark plug comes with a
detachable adapter nut (1), screw
the adapter onto the thread and
tighten it down
firmly
to reduce
the
risk of arcing and fire
.
1
000BA045 KN
4903BA008 KN
Summary of Contents for MS 391
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Page 21: ...STIHL MS 311 391 Instruction Manual...
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