If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterSpecifications
Connecting Rod Big End Bearing Insert Selection
Crankshaft Main Bearing Insert Selection
*: The bearing inserts for Nos. 2 and 4 journals have an oil groove,
respectively. ...
Valve Clearance Inspection
NOTE
Valve clearance must be checked and adjusted when
the engine is cold (at room temperature).
Remove:
Crankshaft Sensor Cover (see Crankshaft Sensor Removal
in the Electrical System chapter)
Cylinder Head Cover (see Cylinder Head Cover Removal
in the Engine Top End chapter)
Turn t ...
Gear Position Switch Installation
Securely place the springs [A] and pins [B] into the holes
[C] of the shift drum.
Apply grease to the new O-ring [D].
Install the gear position switch [E].
Apply a non-permanent locking agent to the threads of
the gear position switch screws [F].
Tighten:
Torque - Gear Position Swit ...