If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterThermostat Removal
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Air Cleaner Housing (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter)
Throttle Body Assy (see Throttle Body Assy Removal in
the Fuel System (DFI) chapter)
Throttle Body Assy Holder Clamp [A]
...
Clutch Installation
Apply engine oil to the needle bearing [A] and the sleeve
[B].
Install:
Needle Bearing
Sleeve
Install the clutch housing [A].
Fit the holes [B] and projections [C].
Engage the clutch housing gear and the crankshaft primary
gear.
Install the spacer [A] and the clutch ...
Valve 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 ...