Engine Running Behavior - Stihl FS 91 Instruction Manual

English
3
WARNING
To reduce the risk of fire and burn injury,
use only spark plugs authorized by
STIHL. Always press the spark plug
boot (1) snugly onto the spark plug
terminal (2).
Do not use a spark plug with a
detachable SAE adapter terminal (3).
Arcing may occur that could ignite
combustible fumes and cause a fire.
This can result in serious injuries or
damage to property.
Only use resistor type spark plugs
N
with solid, non-threaded terminals
Installing the Spark Plug
Screw the spark plug (3) into the
N
cylinder.
Tighten down the spark plug (3) with
N
the combination wrench.
40
Press the boot (2) firmly onto the
N
spark plug.
Fit the cover (1) and screw it down
N
firmly.
1
2

Engine Running Behavior

If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor is properly
adjusted, the cause may be the muffler.
Have the muffler checked for
contamination (carbonization) by your
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
FS 91, FS 91 R