If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterValve Seat Inspection
Remove the valve (see Valve Removal).
Check the valve seating surface [A] between the valve [B]
and valve seat [C].
Measure the outside diameter [D] of the seating pattern
on the valve seat.
If the outside diameter is too large or too small, repair the
seat (see Valve Seat Repair).
Val ...
Air Cleaner Housing Assembly
Install the ducts to the air cleaner housing.
Fit the projections [A] of the duct into the slits [B] on the
air cleaner housing.
Tighten the screws [A].
Torque - Air Cleaner Housing Duct Screws: 1.1 N·m (0.11
kgf·m, 10 in·lb)
Install:
Air Cleaner Gasket [A]
Duct [B] ...
Starter Motor Assembly
Install the positive brush assy [A] and the starter motor
terminal [B] as shown in the figure.
Replace the O-ring [C] with a new one, and install it.
Install:
Brush Springs [A]
Negative Brush Assy [B]
Turn the stopper side [C] to inside.
Tighten:
Torque - Brush Holder S ...