Yamaha YZ450FY 2009 Owner's Service Manual page 218

CHECKING THE COLLAR
1. Inspect:
• Piston metal "1"
Wear/damage → Replace.
CHECKING THE FORK SPRING
1. Measure:
• Fork spring free length "a"
Out of specification → Replace.
Fork spring free length:
454 mm (17.9 in)
<Limit>: 449 mm (17.7 in)
CHECKING THE INNER TUBE
1. Inspect:
• Inner tube surface "a"
Score marks → Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece → Replace.
• Inner tube bends
Out of specification → Replace.
Use the dial gauge "1".
Inner tube bending limit:
0.2 mm (0.008 in)
The bending value is shown by one half of the
dial gauge reading.
Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
CHECKING THE OUTER TUBE
1. Inspect:
• Outer tube "1"
Score marks/wear/damage → Replace.
CHECKING THE ADJUSTER
1. Inspect:
• Adjuster "1"
• O-ring "2"
Wear/damage → Replace.
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FRONT FORK