If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterRebound 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 Sprocket Removal
Remove:
Engine Sprocket Cover Bolts [A]
Engine Sprocket Cover [B]
Flatten out the bended washer [A].
Remove the engine sprocket nut [B] and washer.
NOTE
When loosening the engine sprocket nut, hold the rear
brake on.
Raise the rear wheel off the ground with the stand. ...
Special Tools and Sealant
Oil Pressure Gauge, 5 kgf/cm²:
57001-125
Hand Tester:
57001-1394
Needle Adapter Set:
57001-1457
Extension Tube:
57001-1578
Fuel Pressure Gauge Adapter:
57001-1593
Fuel Hose:
57001-1607
Measuring Adapter:
57001-1700
Liquid Gasket, TB1211:
56019-120
...