Safety Manual

MS 251, MS 251 C
English
48
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 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
N Remove the shroud – see "Shroud"
N Pull off the spark plug boot
N Unscrew spark plug
Checking the spark plug
N Clean the spark plug if it is dirty
N Check the electrode gap (A) and
readjust if necessary – see
"Specifications"
N Use only resistor type spark plugs of
the approved range. See the
chapter "Specifications" in this
instruction manual
Correct the problems that have caused
fouling of the spark plug:
– too much oil in fuel mix;
– dirty air filter; or
– unfavorable running conditions, e.g.
operating at part throttle.
Spark Arresting Screen in
Muffler
2310BA023 KN
2
1
Spark Plug
2310BA006 KN
000BA039 KN
A