KM 56 R, KM 56 RC
English
22
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 off the engine.
N Remove the spark plug boot (1).
N Unscrew the spark plug (2).
Checking the Spark Plug
N Clean dirty spark plug.
N Check electrode gap (A) and 
readjust if necessary – see 
"Specifications."
N Use only resistor type spark plugs of 
the approved range.
Rectify problems that 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 the spark plug into the 
cylinder.
N Press the boot firmly onto the spark 
plug.
Spark Plug