MS 251, MS 251 C
English
45
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
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
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 Use only resistor type spark plugs of
the approved range.
Rectify problems that have caused
fouling of spark plug:
– too much oil in fuel mix,
– dirty air filter,
– unfavorable running conditions, e.g.
operating at part load.
Spark Arresting Screen in
Muffler
Spark Plug