Checking The Spark Plug - Stihl SH 56 Instruction Manual

N
Check the air filter and clean it if
necessary.
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
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
Engine stops while idling
N Check the standard setting.
N Turn the idle speed screw (LA)
clockwise until the engine runs
smoothly.
Erratic idling behavior
If acceleration is poor even though the
standard setting is correct, the idle
setting is too rich:
BG 56, BG 56 C, BG 66, BG 86, BG 86 C, SH 56, SH 56 C, SH 86, SH 86 C
N
Turn the low speed screw (L) slowly
clockwise until the engine runs and
accelerates smoothly.
If acceleration is good, the idle setting is
too lean:
N Turn the low speed screw (L) slowly
counterclockwise until the engine
runs and accelerates smoothly.

Checking the Spark Plug

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.
If engine is down on power, difficult to
start or runs poorly at idling speed, first
check the spark plug.
N Remove spark plug as described in
chapter "Starting / Stopping the
Engine".
N Clean dirty spark plug.
N Check the electrode gap (A) and
readjust if necessary – see
"Specifications".
N
Use only resistor type spark plugs of
the approved range.
English
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