Removing The Transmission; Checking The Shift Forks; Checking The Shift Drum Assembly; Checking The Transmission - Yamaha YZ125X 2021 Owner's Service Manual

EAM30153

REMOVING THE TRANSMISSION

1. Remove:
• Main axle "1"
• Drive axle "2"
TIP
• Tap lightly on the transmission drive axle with
a soft hammer to remove.
• Remove assembly carefully. Note the position
of each part. Pay particular attention to the lo-
cation and direction of shift forks.
EAM30154

CHECKING THE SHIFT FORKS

1. Check:
• Shift fork "1"
Wear/damage/scratches  Replace.
2. Check:
• Shift fork movement
Unsmooth operation  Replace shift fork.
TIP
For a malfunctioning shift fork, replace not only
the shift fork itself but the two gears each adja-
cent to the shift fork.
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.
Main axle runout limit
0.01 mm (0.0004 in)
2. Measure:
• Drive axle runout
(with a centering device and dial gauge "1")
Out of specification  Replace the drive axle.
Drive axle runout limit
0.01 mm (0.0004 in)
5-44
TRANSMISSION