Adjusting The Carburetor; Spark Plug - Stihl FS 111 Instruction Manual

19 Adjusting the Carburetor

18.1 If there is a noticeable loss of
engine power
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► Turn the choke knob to g.
► Loosen the screws (1).
► Remove the filter cover (2).
► Clean away loose dirt from around the filter.
► Remove the filter element (3).
► Replace dirty or damaged filter element (3).
► Replace any damaged parts.
18.2 Installing the Filter Element
► Install the filter element (3) in the filter housing
and fit the cover.
► Insert the screws (1) and tighten them down
firmly.
19 Adjusting the Carburetor
The carburetor has been set at the factory to pro‐
vide an optimum fuel-air mixture under most
operating conditions.
19.1 Adjusting Idle Speed
Engine stops while idling
► Warm up the engine for about 3 minutes.
► Turn the idle speed screw (LA) slowly clock‐
wise until the engine runs smoothly – the cut‐
ting attachment must not run.
Cutting attachment runs when engine is idling
► Turn the idle speed screw (LA) slowly counter‐
clockwise until the cutting attachment stops
0458-430-0121-B
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2
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running and then turn the screw about 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.
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20 Spark Plug

► If the engine is down on power, difficult to start
or runs poorly at idle speed, first check the
spark plug.
► 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 "Specifica‐
tions".
20.1 Removing the Spark Plug
► Remove the cover (1).
► Pull off the spark plug boot (2).
► Unscrew the spark plug (3).
20.2 Checking the Spark Plug
► Clean dirty spark plug.
► Check electrode gap (A) and readjust if neces‐
sary – see "Specifications".
► Rectify the problems which have caused foul‐
ing of the spark plug.
Possible causes are:
– Too much oil in fuel mix.
– Dirty air filter.
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A
English
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