Yamaha WR450F Manuel D'atelier Du Proprietaire page 566

FRONT FORK
EC554200
Base valve
1. Inspect:
Valve assembly 1
G
Wear/damage → Replace.
O-ring 2
G
Damage → Replace.
EC554400
Fork spring
1. Measure:
Fork spring free length a
G
Out of specification → Replace.
Fork spring free length:
Standard
460 mm (18.1 in)
EC554502
Inner tube
1. Inspect:
Inner tube surface a
G
Score marks → Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece → Replace.
Inner tube bends
G
Out of specification → Replace.
Use the dial gauge 1.
Inner tube bending limit:
0.2 mm (0.008 in)
NOTE:
The bending value is shown by one half of the
dial gauge reading.
WARNING
Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
EC554600
Outer tube
1. Inspect:
Outer tube 1
G
Score marks/wear/damage → Replace.
5 - 31
CHAS
Limit
455 mm (17.9 in)