Adjusting The Engine Idling Speed - Yamaha WR450F Owner's Service Manual

ADJUSTING THE ENGINE IDLING SPEED

EAS2GC1098
TIP
• Because the air pressure is lower at high alti-
tudes, the air-fuel mixture will become richer.
If the idling speed is low, turn the starter knob/
idle screw a few clicks counterclockwise to in-
crease the speed before the adjustment.
• Before adjusting the engine idling speed,
make sure that the air filter element is not
clogged, the engine compression is proper,
and the throttle grip free play is proper.
• Adjust the engine idling speed with the starter
knob/idle screw pushed in completely.
1. Start the engine, and warm this up until the
oil has reached the specified temperature.
TIP
This model is equipped with an engine auto-
stop system. The engine stops automatically if
left idling for 7 minutes. If the engine stops,
push the start switch or push down the kick-
starter lever to restart the engine.
2. Attach the pocket tester with temperature
probe "1" to the oil drain bolt.
Oil temperature
70–80 °C (158–176 °F)
3. Install:
• Digital tachometer
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
1
3-19
TIP
Get the high tension cord "1" of the ignition coil
pinched in the detector "a" of the digital tachom-
eter.
1
a
4. Measure:
• Engine idling speed
Out of specification  Regulate.
Engine idling speed
1900–2100 r/min
5. Adjust:
• Engine idling speed
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a. Turn the starter knob/idle screw "1" in the di-
rection of "a" or "b" to make an adjustment.
b
a
Engine idling speed  De-
Direction "a"
creases.
Engine idling speed  In-
Direction "b"
creases.
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ENGINE
1
a
1