Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionValve Guide Removal
Remove:
Valve (see Valve Removal)
Oil Seal
Spring Seat
Heat the area around the valve guide to 120
150°C (248
302°F), and hammer lightly on
the valve guide arbor [A]
to remove the guide from the top of the head.
NOTICE
Do not heat the cylinder head with a torch. This ...
Additional Considerations for High Speed Operation
Brakes: The importance of the brakes, especially during high speed
operation,
cannot be overemphasized. Check to see that they are correctly adjusted and
functioning
properly.
Steering: Looseness in the steering can cause loss of control. Check to see that
the handlebar turns freely but ha ...
Transmission Shaft Assembly
Apply molybdenum disulfide oil solution to the sliding surfaces
of the gears and shafts.
Install the gears and the gear bushings [A] with their holes
[B] aligned.
Replace any circlips removed with new ones.
Install the circlips [A] so that the opening [B] of it is aligned
with ...