Yamaha RD250 Owner's Manual page 42

Drive Chain
(A) Lubrication
Remove the dirt and dust from the chain
at least every 100 miles (150 km) and
lubricate it.
(B) Adjustment
1. Loosen the wheel axle nut. ®
2. Loosen the wheel nut.®
3. Loosen the lock nut.®
4. Adjust the chain by turning the chain
adjusting bolt.®
The chain should have a play of 3/4"
(20 mm) up and down at the center of
the lower section with the rear wheel
on the ground.
5. Lock the chain adjusting bolt with the
nut.
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