Yamaha YZ450FX 2021, Owner'S Service Manual

Page: 257 / 374

TRANSMISSION
5-71
EAM30153
REMOVING THE TRANSMISSION
1. Remove:
•
Long shift fork guide bar “1”
• Short shift fork guide bar “2”
•
Shift cam “3”
• Shift fork 3 “4”
•
Shift fork 2 “5”
• Shift fork 1 “6”
•
Main axle “7”
• Drive axle “8”
•
Collar “9”
TIP
•
Remove assembly with the collar “9” installed
to the crankcase.
• Make a note of the position of each part. Pay
particular attention to the location and direction
of shift forks.
•
Remove the main axle and the drive axle all to-
gether by tapping the drive axle lightly with a
soft hammer.
EAM30154
CHECKING THE SHIFT FORKS
1. Check:
• Shift fork cam follower “1”
•
Shift fork pawl “2”
Bends/damage/scoring/wear

Replace the
shift fork.
2. Check:
• Shift fork guide bar
Roll the shift fork guide bar on a flat surface.
Bends

Replace.
WARNING
EWA12840
Do not attempt to straighten a bent shift fork
guide bar.
3. Check:
•
Shift fork movement
(along the shift fork guide bar)
Rough movement

Replace the shift forks
and shift fork guide bar as a set.
EAM30155
CHECKING THE SHIFT DRUM ASSEMBLY
1. Check:
•
Shift drum groove
Damage/scratches/wear

Replace the shift
drum assembly.
• Shift drum segment
Damage/wear

Replace the shift drum as-
sembly.
EAM30156
CHECKING THE TRANSMISSION
1. Measure:
•
Main axle runout
(with a centering device and dial gauge “1”)
Out of specification

Replace the main axle.
2
5
6
3
4
1
7
8
9
Main axle runout limit
0.08 mm (0.0032 in)