Yamaha YZ450FP 2023, Owner'S Service Manual

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ENGINE
3-12
EAM30412
CHECKING THE ENGINE IDLING SPEED
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 idle screw
clockwise to increase the speed before the ad-
justment.
•
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 pulled in completely.
1. Start the engine, and warm this up until the oil
has reached the specified temperature.
2. Measure the coolant temperature using the
Yamaha diagnostic tool.
3. Install:
• Digital tachometer
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
4. Measure:
•
Engine idling speed
Out of specification

Regulate.
5. Adjust:
• Engine idling speed
a. Turn the idle screw “1” to make an adjust-
ment.
EAM30475
CHECKING THE THROTTLE GRIP
TIP
Prior to adjusting throttle grip free play, the en-
gine idling speed should be adjusted.
1. Check:
•
Throttle grip free play “a”
Out of specification

Regulate.
2. Adjust:
• Throttle grip free play
a. Loosen the locknut “1”.
b. Turn the adjuster “2” until the specified
throttle grip free play is obtained.
c. Tighten the locknut.
WARNING
EWA18470
After adjusting the throttle grip free play,
start the engine and turn the handlebar to the
right and to the left to ensure that this does
not cause the engine idling speed to change.
Yamaha diagnostic tool USB (US)
90890-03269
Yamaha diagnostic tool (A/I)
90890-03264
Coolant temperature
70–80  C (158–176  F)
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
1
a
a a
1 1
Engine idling speed
1900–2100 r/min
Throttle grip free play
3.0–6.0 mm (0.12–0.24 in)
1 1