Stihl PH 90 Instruction Manual - Page 39

Spark Plug

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Spark Plug Checking the Spark Plug English 249BA063 KN 000BA039 KN 002BA363 KN 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 Move the slide control to STOP-0. 1 N Pull off the spark plug boot (1). N Unscrew the spark plug. A N Clean dirty spark plug. N Check electrode gap (A) and readjust if necessary - see chapter "Specifications." N Use only resistor type spark plugs of 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. 1 2 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 securely attached.) A loose connection between spark plug boot and ignition wire connector in the boot may create arcing that could ignite combustible fumes and cause a fire. Installing the spark plug N Screw home the spark plug, fit the boot and press it down firmly. FS 90, FS 90 R 37

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FS 90, FS 90 R
English
37
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
Move the slide control to
STOP
-
0
.
N
Pull off the spark plug boot (1).
N
Unscrew the spark plug.
Checking the Spark Plug
N
Clean dirty spark plug.
N
Check electrode gap (A) and
readjust if necessary – see chapter
"Specifications."
N
Use only resistor type spark plugs of
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.
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
securely attached.) A loose connection
between spark plug boot and ignition
wire connector in the boot may create
arcing that could ignite combustible
fumes and cause a fire.
Installing the spark plug
N
Screw home the spark plug, fit the
boot and press it down firmly.
Spark Plug
1
249BA063 KN
000BA039 KN
A
2
1
002BA363 KN