Yamaha YZ125 2021 Owner's Service Manual page 206

• When installing the collar into the crankcase,
pay careful attention to the crankcase oil seal
lip.
5. Install:
• Shift fork 1 (L) "1"
• Shift fork 2 (C) "2"
• Shift fork 3 (R) "3"
TIP
• Apply the molybdenum disulfide oil on the shift
fork grooves.
• Mesh the shift fork 1 (L) with the 5th wheel gear
"4" and 3 (R) with the 6th wheel gear "6" on the
drive axle.
• Mesh the shift fork 2 (C) with the 3rd/4th pinion
gear "5" on the main axle.
6. Install:
• Shift cam "1"
TIP
• Apply the transmission oil on the shift cam.
• Install the shift cam while holding up the 5th
wheel gear "2" and keeping the shift fork 1 "3"
moved in the direction of the arrow.
1
7. Install:
• Guide bar (short) "1"
• Guide bar (long) "2"
TIP
• Apply the transmission oil on the guide bars.
• Be sure the long bar is inserted into the shift
forks 1 and 3 and the short one into 2.
8. Check:
• Shifter operation
• Transmission operation
Unsmooth operation  Repair.
5-46
TRANSMISSION