If there are notches worn into the splines, replace the sub clutch hub. Also, replace the steel plates if their teeth are damaged.

Clutch Housing Finger Inspection
Damper Cam InspectionRebound Damping Force Adjustment
To adjust the rebound damping force, turn the rebound
damping adjuster [A] to the desired position.
The standard adjuster setting is the 1 3/4 turns out from
the fully clockwise position.
Rebound Damping Force Adjustment
...
Engine Oil Flow Chart
1. Oil Screen
2. Oil Pump
3. Oil Pressure Relief Valve
4. Oil Filter
5. Oil Pipe
6. Oil Cooler
7. Balancer Oil Passage
8. Main Oil Passage
9. Crankshaft Oil Passage
10. Oil Pressure Switch
11. Camshaft Oil Passages
12. Drive Shaft Oil Passage
13. Output Shaft Oil Passage
14. Starter ...
Transmission Assy Installation
Assemble the transmission assy (see Transmission Assy
Assembly).
Be sure that the dowel pins are in position.
Install the transmission assy on the crankcase.
Tighten:
Torque - Transmission Case Bolts: 20 N·m (2.0 kgf·m, 15
ft·lb)
Install:
Shift Shaft (see External Shift Mechani ...