Engine Management; Adjusting The Carburetor; Spark Arresting Screen In Muffler - Stihl BT 131 Instruction Manual

Engine Management

Exhaust emissions are controlled by the
design of the engine and components
(e.g. carburation, ignition, timing and
valve or port timing).
BT 131

Adjusting the Carburetor

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
Warm up the engine for about
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3 minutes.
Turn the idle speed screw (LA)
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slowly clockwise until the engine
runs smoothly – the auger must not
rotate.
Auger rotates when engine is idling
Turn the idle speed screw (LA)
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slowly counterclockwise until the
auger stops rotating and then turn
the screw about another 1/2 to 3/4
turn in the same direction.
WARNING
If the auger continues to rotate when the
engine is idling, have your machine
checked and repaired by your servicing
dealer.
Spark Arresting Screen in
Muffler
If the engine is down on power,
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check the spark arresting screen in
the muffler.
Wait for the muffler to cool down.
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4
5
Take out the screw (4).
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Lift the spark arresting screen (5)
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and pull it out.
Clean the spark arresting
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screen (5). If the screen is damaged
or heavily carbonized, install a new
one.
Refit the spark arresting screen (5).
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Insert the screw (4) and tighten it
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down firmly.
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