BG 56, BG 56 C, BG 66, BG 86, BG 86 C, SH 56, SH 56 C, SH 86, SH 86 C
English
19
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:
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.
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.
295BA077 KN
Checking the Spark Plug
000BA002 KN