Yamaha YZ450FY 2009 Owner's Service Manual page 188

REMOVING THE TRANSMISSION
1. Remove:
• Main axle "1"
• Drive axle "2"
• Shift cam
• Shift fork 3
• Shift fork 2
• Shift fork 1
• Remove assembly with the collar "3" installed
to the crankcase.
• Remove assembly carefully. Note the position
of each part. Pay particular attention to the lo-
cation and direction of shift forks.
• Remove the main axle, drive axle, shift cam
and shift fork all together by tapping lightly on
the transmission drive axle with a soft ham-
mer.
CHECKING THE GEARS
1. Inspect:
• Matching dog "a"
• Gear teeth "b"
• Shift fork groove "c"
Wear/damage → Replace.
TRANSMISSION, SHIFT CAM AND SHIFT FORK
4-87
2. Inspect:
• O-ring "1"
Damage → Replace.
3. Check:
• Gears movement
Unsmooth movement → Repair or replace.
CHECKING THE BEARING
1. Inspect:
• Bearing "1"
Rotate inner race with a finger.
Rough spot/seizure → Replace.
CHECKING THE SHIFT FORK, SHIFT CAM
AND SEGMENT
1. Inspect:
• Shift fork "1"
Wear/damage/scratches → Replace.