Yamaha YZ125 2002 Manuel D'atelier Du Proprietaire page 334

ENGINE REMOVAL
2. Install:
9 Lock washer 1
9 Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
3. Bend the lock washer tab to lock the nut.
4. Install:
9 Chain cover 1
9 Screw (chain cover) 2
4-61
ENG
65 Nm (6.5 m•kg, 47 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)