FS 40, FS 40 C, FS 50, FS 50 C
English
27
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.
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.
To help prolong the wear life of the 
starter rope, observe the following 
points:
N Pull the starter rope only in the 
direction specified.
N Do not pull the rope over the edge of 
the guide bushing.
N Do not pull out the rope more than 
specified.
N Do not allow the starter grip to snap 
back, guide it back into the housing 
slowly – see chapter on "Starting / 
Stopping the Engine."
Have a damaged starter rope replaced 
by your dealer before it breaks 
completely. STIHL recommends that 
you have servicing and repair work 
carried out exclusively by an authorized 
STIHL servicing dealer.
Engine Running Behavior Rewind Starter