Engine Management; Adjusting The Carburetor; Spark Arresting Screen In Muffler - Stihl FS 90 Instruction Manual

English

Engine Management

Exhaust emissions are controlled by the
design of the fundamental engine
parameters and components (e.g.
carburation, ignition, timing and valve or
port timing) without the addition of any
major hardware.
36

Adjusting the Carburetor

The carburetor of the machine has been
adjusted for optimum performance and
fuel efficiency in all operating states at
the factory.
Setting the idle speed
LA
Engine stops when idling
Let the engine warm up for approx.
N
3 min
Slowly turn idle speed screw (LA)
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clockwise until the engine runs
smoothly – the cutting attachment
must not rotate
Cutting attachment turns when idling
Turn the idle speed screw (LA)
N
slowly counterclockwise until the
cutting attachment stops moving –
then turn another 1/2 to 3/4 turn in
the same direction
WARNING
If the cutting attachment continues to
keep rotating in idle even after
adjustment, have the machine checked
by a servicing dealer.
Spark Arresting Screen in
Muffler
The muffler is equipped with a spark
arresting screen.
If the engine is down on power,
N
check the spark arresting screen in
the muffler.
Wait for the muffler to cool down.
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Move the slide control to STOP-0.
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Take out the screw (1).
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3
2
Take out the screws (2) and remove
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the shroud (3).
FS 90, FS 90 R
1
2