Adjusting The Carburetor; Adjusting The Engine Idling Speed - Yamaha YFM125GZ Owner's Manual

EBU23940

Adjusting the carburetor

The carburetor should be checked and, if neces-
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sary, adjusted at the intervals specified in the peri-
odic maintenance and lubrication chart. The
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carburetor is an important part of the engine and
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requires very sophisticated adjustment. Therefore,
most carburetor adjustments should be left to a
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Yamaha dealer, who has the necessary profes-
sional knowledge and experience. The adjustment
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described in the following section, however, may
be performed by the owner as part of routine main-
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tenance.
ECB00480
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NOTICE
The carburetor has been set and extensively
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tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
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edge may result in poor performance of or
damage to the engine.
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EBU24000

Adjusting the engine idling speed

The engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance and lubrica-
tion chart.
TIP
A diagnostic tachometer is needed to make this
adjustment.
1. Start the engine and warm it up.
TIP
The engine is warm when it quickly responds to the
throttle.
2. Attach the tachometer to the spark plug lead.
3. Check the engine idling speed and, if neces-
sary, adjust it to specification by turning the
throttle stop screw at the carburetor. To in-
crease the engine idling speed, turn the throt-
tle stop screw in direction (a), and to decrease
it, turn the screw in direction (b).
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