BG 56, BG 56 C, BG 66, BG 86, BG 86 C, SH 56, SH 56 C, SH 86, SH 86 C
English
21
Checking the Spark Plug
N Clean dirty spark plug.
N Check electrode gap (A) and 
readjust if necessary – see chapter 
"Specifications."
N Use only resistor type spark plugs of 
the approved range.
Rectify problems which 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 (3) into the 
cylinder and fit the boot (2) (press it 
down firmly).