FS 40, FS 40 C, FS 50, FS 50 C
English
26
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.
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.
Adjusting the Carburetor
Spark Plug