Stihl SR 450 Product Instruction Manual - Page 33

Spark Plug

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L H LA N Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn). N Turn the low speed screw (L) carefully clockwise as far as stop, then turn it back 1 turn. N Start and warm up the engine. Adjusting Idle Speed Engine stops while idling N Check the standard setting. N Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly. 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) slowly counterclockwise until the engine runs and accelerates smoothly. Erratic idling behavior Idle setting is too rich N Turn the low speed screw (L) clockwise until the engine runs and accelerates smoothly. 0002BA048 KN 0002BA049 KN It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). 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 Check the standard setting. N Warm up the engine. At high altitude N Turn high speed screw (H) clockwise (leaner) - no further than stop. If the setting is too lean there is a risk of engine damage due to insufficient lubrication and overheating. At sea level N Turn high speed screw (H) slightly counterclockwise (richer) - no further than stop. Spark Plug English 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 2 N Pull off the spark plug boot (1) vertically. N Unscrew the spark plug (2). SR 430, SR 450 31

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SR 430, SR 450
English
31
N
Turn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N
Turn the low speed screw (L)
carefully clockwise as far as stop,
then turn it back 1 turn.
N
Start and warm up the engine.
Adjusting Idle Speed
Engine stops while idling
N
Check the standard setting.
N
Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly.
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) slowly
counterclockwise until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N
Turn the low speed screw (L)
clockwise until the engine runs and
accelerates smoothly.
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
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
Check the standard setting.
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.
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
Pull off the spark plug boot (1)
vertically.
N
Unscrew the spark plug (2).
0002BA048 KN
H
LA
L
If the setting is too lean there is a
risk of engine damage due to
insufficient lubrication and
overheating.
Spark Plug
2
0002BA049 KN