Honda CRF125F 2022 Owner's Manual page 88

6. Inspect the sprocket teeth for possible wear
or damage.
Damaged Sprocket
Teeth
REPLACE
Normal Sprocket Teeth
GOOD
If the drive chain or sprockets are excessively
worn or damaged, they should be replaced.
Never use a new chain with worn sprockets;
rapid chain wear will result.
78
Worn Sprocket Teeth
REPLACE
Adjustment:
If the drive chain requires adjustment, the
procedure is as follows:
1. Place a support block under the engine to
raise the rear wheel off the ground.
2. Loosen the rear axle nut (1).
3. Loosen the lock nuts (2) on both right and
left chain adjusters.
(4)
(3)
(2)
(1) Rear axle nut
(2) Lock nut
(3) Adjusting nut
(5)
(1)
(4) Notch
(5) Graduated scale