Spark Plug - Stihl FS 90 Manual De Instrucciones

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
Move the slide control to STOP-0.
N
1
Pull off the spark plug boot (1).
N
Unscrew the spark plug.
N
FS 90, FS 90 R
Checking the Spark Plug
Clean dirty spark plug.
N
Check electrode gap (A) and
N
readjust if necessary – see
"Specifications".
Use only resistor type spark plugs of
N
the approved range.
Rectify problems which have caused
fouling of spark plug:
– Too much oil in fuel mix.
– Dirty air filter.
– Unfavorable running conditions,
e.g. operating at part load.
A
Warning!
To reduce the risk of fire and burn injury,
use only spark plugs authorized by
STIHL. Always press spark plug boot (1)
snugly onto spark plug terminal (2) of
the proper size. (Note: If terminal has
detachable SAE adapter nut, it must be
attached.) A loose connection between
spark plug boot and ignition wire con-
nector in the boot may create arcing that
could ignite combustible fumes and
cause a fire.
Installing the spark plug
Screw home the spark plug, fit the
N
boot and press it down firmly.
English
1
2
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