Honda CRF230F Owner's Manual page 83

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 (2) while holding
the axle.
3. Turn both the right and left adjusters (3)
equally to increase or decrease chain
slack.
4. After adjusting, be sure the same adjuster
index marks (4) align with the stopper
pins (5) on both sides of the swingarm.
If the drive chain slack is excessive when the
rear axle is moved to the furthest limit of
adjustment, the drive chain is worn and must
be replaced.
72
(5)
(4)
(3)
(1) Axle
(2) Axle nut
(3) Chain adjuster
(1)
(4)
(3)
(5)
(2)
(4) Index mark
(5) Stopper pin