If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterBrake Light Switch Operation Inspection
Turn the ignition switch to ON.
The brake light (LED) [A] should go on when the brake
lever is applied or after the brake pedal is depressed
about 10 mm (0.39 in.).
If it does not, adjust the brake light switch.
Remove the front footpeg bracket (see Brake Pedal Removal
in the B ...
Lower Crankcase Assembly
Install the ball bearing [A] and the oil level inspection window
[B] until they are bottomed
Apply soap and water solution to the oil level inspection
window before installation.
Install the new circlip [C].
Apply a non-permanent locking agent to the oil passage
plug [D].
Tighten: ...
Fuel Tank and Cap Inspection
Visually inspect the gasket [A] on the tank cap for any
damage.
Replace the gasket if it is damaged.
Check to see if the water drain pipe [B] and fuel breather
pipe [C] in the tank are not clogged. Check the tank cap
breather also.
If they are clogged, remove the tank and drain it ...