Adjusting The Engine Idling Speed - Yamaha BIG BEAR 400 Owner's Manual

ECB00480
CAUTION:
The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine.
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.
NOTE:
A diagnostic tachometer is needed to make this
adjustment.
1. Start the engine and warm it up.
NOTE:
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).
1. Throttle stop screw
Engine idling speed:
1450–1550 r/min
NOTE:
If the specified idling speed cannot be obtained as
described above, have a Yamaha dealer make the
adjustment.
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