Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionHub Bearing Removal
Remove the wheels (see Front/Rear Wheel Removal),
and take out the following.
Collars
Coupling (Out of rear hub)
Grease Seals
Use the bearing remover to remove the hub bearings [A].
NOTICE
Do not lay the wheel on the ground with the disc
facing down. This can damage or warp the d ...
Air Cleaner Element Replacement
NOTE
In dusty areas, the element should be replaced more
frequently than the recommended interval.
WARNINGIf dirt or dust is allowed to pass through
into the
throttle body assy, the throttle may become stuck,
possibly causing accident. Replace the air cleaner
element according ...
Exploded View
EO: Apply engine oil.
G: Apply grease.
L: Apply a non-permanent locking agent.
Lh: Left-hand Threads
MO: Apply molybdenum disulfide oil solution.
(mixture of the engine oil and molybdenum disulfide grease in a weight ratio
10:1)
R: Replacement Parts
S: Follow the specified t ...