Adjusting The Carburetor - Stihl MM 55 Manual De Instrucciones

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Adjusting the Carburetor

The carburetor comes from the factory
with a standard setting.
The carburetor has been adjusted for
optimum performance and fuel
efficiency in all operating states.
The high speed adjusting screw on this
carburetor can only be set within narrow
limits!
Standard position
Switch off the engine
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Mount MultiTool
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Check the air filter – replace if
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necessary
Have the spark arrestor (present
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only in some countries) checked –
see "Inspection and maintenance
by the servicing dealer"
18
Turn the high speed screw (H)
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counterclockwise as far as possible
– max. 3/4 turn
Carefully turn the low speed
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adjusting screw (L) clockwise until it
is firmly seated, then open it 1 turn
counterclockwise
Start the engine and let it warm up if
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necessary
Using the idle speed screw (LA), set
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the idle speed so that the working
tool does not move
Fine adjustment
A marginal adjustment of the setting of
the high speed adjusting screw (H) may
be necessary if the engine does not run
satisfactorily in mountain country or at
sea level.
Approx. value
Turn the high speed screw (H) approx.
1/4 turn per 1000 m (3300 ft) difference
in elevation.
Adjustment conditions
Adjust to standard setting
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Let the engine warm up for
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approx. 3 min at full throttle
In the mountains
Turn the high speed screw (H)
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clockwise (leaner) – until there is no
longer a noticeable increase in
speed – max. as far as possible
At sea level
Turn the high speed screw (H)
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counterclockwise (richer) – until
there is no longer a noticeable
increase in speed – max. as far as
possible
It is possible that the maximum speed is
already obtained at the standard setting.
Setting the idle speed
Whenever the low speed screw (L) has
been adjusted, it is usually also
necessary to adjust the idle speed
adjusting screw (LA).
Let the engine warm up for
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approx. 3 min
Engine stops when idling
Slowly turn idle speed screw (LA)
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clockwise until the engine runs
smoothly – the working tool must not
move
MM 55, MM 55 C