Yamaha YZ450F(D) Owner's Service Manual page 77

CHECKING THE TIRE PRESSURE
1. Measure:
• Tire pressure
Out of specification → Adjust.
Standard tire pressure:
100 kPa (1.0 kgf/cm
15 psi)
• 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.
2
,
Spoke nipple wrench:
YM-01521/90890-01521
Spokes:
3 Nm (0.3 m•kg, 2.2
ft•lb)
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.
3-21
CHASSIS
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".
Steering nut wrench:
YU-33975/90890-01403
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.
Steering nut wrench:
YU-33975/90890-01403
Steering ring nut (initial
tightening):
38 Nm (3.8 m•kg, 27
ft•lb)