Instruction Manual

FS 40, FS 40 C, FS 50, FS 50 C
English
19
The carburetor has been set at the
factory to provide an optimum fuel-air
mixture under most operating
conditions.
Adjusting Idle Speed
Engine stops while idling
N Warm up the engine for about
3 minutes.
N Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting
attachment must not run.
Cutting attachment runs when engine is
idling
N Turn the idle speed screw (LA)
counterclockwise until the cutting
attachment stops moving and then
rotate the screw another 1/2 to 3/4
turn in the same direction.
WARNING
If the cutting attachment continues to run
when the engine is idling, have your
machine checked and repaired by your
servicing dealer.
N If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
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 Rectify the problems which have
caused fouling of the spark plug.
Possible causes are:
– Too much oil in fuel mix.
– Dirty air filter.
– Unfavorable running conditions.
WARNING
Arcing may occur if the adapter nut (1) is
loose or missing. Working in an easily
combustible or explosive atmosphere
may cause a fire or an explosion. This
can result result in serious injuries or
damage to property.
Adjusting the Carburetor
0815BA006 KN
Spark Plug
1
547BA041 KN
2
000BA039 KN
A
1
000BA045 KN