Stihl MS 251 C-Q

MS 251 C-Q
English
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N If engine performance deteriorates,
check the spark arresting screen in
the muffler
N Let the muffler cool down
N Unscrew the screw (1)
N Pull out spark arresting screen (2)
N Clean the dirty spark arresting
screen, replace if damaged or
heavily carbonized
N Refit the spark arresting screen
N Fit screw
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".
Removing the spark plug
N Remove the shroud – see "Shroud"
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.
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.
Spark Arresting Screen in
Muffler
2310BA023 KN
2
1
Spark Plug
2310BA006 KN
000BA039 KN
A
1
000BA045 KN