Yamaha YZ450FY 2009 Owner's Service Manual page 217

2. Remove:
• Inner tube "1"
Oil seal removal steps:
a. Push in slowly "a" the inner tube just before
it bottoms out and then pull it back quickly
"b".
b. Repeat this step until the inner tube can be
pulled out from the outer tube.
REMOVING THE BASE VALVE
1. Remove:
• Base valve "1"
From damper assembly "2".
Hold the damper assembly with the cap bolt
ring wrench "3" and use the cap bolt wrench "4"
to remove the base valve.
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501
CHECKING THE DAMPER ASSEMBLY
1. Inspect:
• Damper assembly "1"
Bend/damage → Replace.
• O-ring "2"
Wear/damage → Replace.
The front fork with a built-in piston rod has
a very sophisticated internal construction
and is particularly sensitive to foreign mate-
rial.
Use enough care not to allow any foreign
material to come in when the oil is replaced
or when the front fork is disassembled and
reassembled.
CHECKING THE BASE VALVE
1. Inspect:
• Base valve "1"
Wear/damage → Replace.
Contamination → Clean.
• O-ring "2"
Wear/damage → Replace.
• Piston metal "3"
Wear/damage → Replace.
• Spring "4"
Damage/fatigue → Replace base valve.
• Air bleed screw "5"
Wear/damage → Replace.
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FRONT FORK