Spark Arresting Screen In Muffler; Spark Plug - Stihl MS 251 Manual De Instrucciones

English
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
Fine Tuning for Operation at High
Altitude
A slight correction of the setting may be
necessary if engine does not run
satisfactorily:
Carry out the standard setting.
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Warm up the engine.
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Turn high speed screw (H) slightly
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clockwise (leaner) – no further than
stop.
NOTICE
After returning from high altitude, reset
the carburetor to the standard setting.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
44
Spark Arresting Screen in
Muffler
In some countries, the muffler is fitted
with a spark arresting screen.
If engine performance deteriorates,
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check the spark arresting screen in
the muffler
Let the muffler cool down
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1
2
Remove screw (1)
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Pull out spark arresting screen (2)
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Clean the dirty spark arresting
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screen, replace if damaged or
heavily carbonized
Refit the spark arresting screen
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Fit screw
N

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
Remove the shroud – see "Shroud"
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Pull off the spark plug boot
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Unscrew spark plug
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MS 251, MS 251 C