Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionAir Suction Valve Installation
Install the air suction valve so that opening [A] of the reed
faces downward.
Apply a non-permanent locking agent to the threads of
the air suction valve cover bolts [A], and tighten them.
Torque - Air Suction Valve Cover Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)
...
Air Intake Duct Assembly (Other than US, CA and CAL Models)
Install the seals [A] as shown in the figure.
Fit the projections [A] of the air intake valve to the hole [B]
of the air intake ducts.
Tighten:
Torque - Air Intake Duct Assembly Screws: 1.5 N·m (0.15
kgf·m, 13 in·lb)
Hang the shaft [A] to the air intake valve securely ...
Coupling Bearing Removal
Remove:
Coupling
Grease Seal
Circlip [A]
Special Tool - Inside Circlip Pliers: 57001-143
Remove the bearing [A] by tapping from the wheel side.
Special Tool - Bearing Driver Set [B]: 57001-1129
...