Stihl FC 70 Product Instruction Manual - Page 25

Spark Plug

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N Start and warm up the engine if necessary. N Adjust idle speed with the idle speed screw (LA) so that the cutting blade does not turn. Fine Tuning for Operation in Mountains or at Sea Level A slight correction of the setting may be necessary if engine power is not satisfactory when operating at high altitude or at sea level. N Warm up the engine. At high altitude N Turn high speed screw (H) clockwise (leaner) - no further than stop. At sea level N Turn high speed screw (H) slightly counterclockwise (richer) - no further than stop. Adjusting Idle Speed N Warm up the engine. Engine stops while idling N Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly - the cutting blade must not turn. Cutting blade rotates when engine is idling N Turn the idle speed screw (LA) counterclockwise until the blade stops moving and then turn the screw another full turn in the same direction. If the cutting blade continues to rotate when the engine is idling, have your machine checked and repaired by your servicing dealer. Erratic idling behavior, engine stops even though setting of LA screw has been corrected, poor acceleration Idle setting is too lean N Turn the low speed screw (L) counterclockwise, no further than stop, until the engine runs and accelerates smoothly. Erratic idling behavior, engine speed drops when swinging the machine Idle setting is too rich N Turn the low speed screw (L) clockwise (1/8 of a turn or 45° at a time) until the engine runs smoothly and accelerates well. It is usually necessary to change the setting of the idle speed screw (LA) after corrections to the low speed screw (L). English 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 N Shut odd the engine. 1 2 N Pull off the spark plug boot (1). N Unscrew the spark plug (2). 0141BA020 KN FC 70 C 23

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FC 70 C
English
23
N
Start and warm up the engine if
necessary.
N
Adjust idle speed with the idle speed
screw (LA) so that the cutting blade
does not turn.
Fine Tuning for Operation in Mountains
or at Sea Level
A slight correction of the setting may be
necessary if engine power is not
satisfactory when operating at high
altitude or at sea level.
N
Warm up the engine.
At high altitude
N
Turn high speed screw (H)
clockwise (leaner) – no further than
stop.
At sea level
N
Turn high speed screw (H) slightly
counterclockwise (richer) – no
further than stop.
Adjusting Idle Speed
N
Warm up the engine.
Engine stops while idling
N
Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting blade
must not turn.
Cutting blade rotates when engine is
idling
N
Turn the idle speed screw (LA)
counterclockwise until the blade
stops moving and then turn the
screw another full turn in the same
direction.
If the cutting blade continues to rotate
when the engine is idling, have your
machine checked and repaired by your
servicing dealer.
Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
N
Turn the low speed screw (L)
counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.
Erratic idling behavior, engine speed
drops when swinging the machine
Idle setting is too rich
N
Turn the low speed screw (L)
clockwise (1/8 of a turn or 45° at a
time) until the engine runs smoothly
and accelerates well.
It is usually necessary to change the
setting of the idle speed screw
(LA) after
corrections to the low speed screw (L).
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
Shut odd the engine.
N
Pull off the spark plug boot (1).
N
Unscrew the spark plug (2).
Spark Plug
2
0141BA020 KN
1