Yamaha YZ450F(D), Owner'S Service Manual

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3-21
CHASSIS
CHECKING THE TIRE PRESSURE
1. Measure:
• Tire pressure
Out of specification
→
Adjust.
• Check the tire while it is cold.
• Loose bead stoppers allow the tire
to slip off its position on the rim
when the tire pressure is low.
• A tilted tire valve stem indicates that
the tire slips off its position on the
rim.
• If the tire valve stem is found tilted,
the tire is considered to be slipping
off its position. Correct the tire posi-
tion.
CHECKING AND TIGHTENING THE
SPOKES
The following procedure applies to all
of the spokes.
1. Check:
• Spokes
Bend/damage
→
Replace.
Loose spoke
→
Retighten.
Tap the spokes with a screw-
driver.
A tight spoke will emit a clear, ringing
tone; a loose spoke will sound flat.
2. Tighten:
• Spokes
(with a spoke nipple wrench "1")
Be sure to retighten these spokes be-
fore and after break-in.
CHECKING THE WHEELS
1. Inspect:
• Wheel runout
Elevate the wheel and turn it.
Abnormal runout
→
Replace.
2. Inspect:
• Bearing free play
Exist play
→
Replace.
CHECKING AND ADJUSTING THE
STEERING HEAD
1. Place a stand under the engine to
raise the front wheel off the
ground.
WARNING! Securely
support the vehicle so that
there is no danger of it falling
over.
2. Check:
• Steering stem
Grasp the bottom of the forks and
gently rock the fork assembly
back and forth.
Free play
→
Adjust steering head.
3. Check:
• Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action
→
Adjust steer-
ing ring nut.
4. Adjust:
• Steering ring nut
Steering ring nut adjustment
steps:
a. Remove the number plate.
b. Remove the handlebar and upper
bracket.
c. Loosen the steering ring nut "1"
using the steering nut wrench "2".
d. Tighten the steering ring nut "3"
using steering nut wrench "4".
• Apply the lithium soap base grease
on the thread of the steering stem.
• Set the torque wrench to the steer-
ing nut wrench so that they form a
right angle.
Standard tire pressure:
100 kPa (1.0 kgf/cm
2
,
15 psi)
Spoke nipple wrench:
YM-01521/90890-01521
Spokes:
3 Nm (0.3 m•kg, 2.2
ft•lb)
Steering nut wrench:
YU-33975/90890-01403
Steering nut wrench:
YU-33975/90890-01403
Steering ring nut (initial
tightening):
38 Nm (3.8 m•kg, 27
ft•lb)