If a master cylinder or piston shows any damage, replace them.

If a cup is worn, damaged softened (rotted), or swollen, the piston assembly should be replaced to renew the cups.
If fluid leakage is noted at the brake lever, the piston assembly should be replaced to renew the cups.
If they are damaged, replace them.
If the springs are damaged, replace them.
If the relief port becomes plugged, the brake pads will drag on the disc. Blow the ports clean with compressed air.
Front Master Cylinder [I] Rear Master Cylinder [J]

Rear Master Cylinder Installation
Brake DiscConnecting Rod Twist Inspection
With the big-end arbor [A] still on V block [C], hold the
connecting rod horizontally and measure the amount that
the arbor [B] varies from being paralleled with the surface
plate over a 100 mm (3.94 in.) length of the arbor to determine
the amount of connecting rod twist.
If the conne ...
Hub Bearing Installation
Before installing the hub bearings, blow any dirt or foreign
particles out of the hub with compressed air to prevent
contamination of the bearings.
Replace the bearings with new ones.
Install the bearings by using the bearing driver set which
does not contact the bearing inner race.
...
Air Intake Duct Assembly (US, CA and CAL Models)
Install the dampers [A] and seal [B] as shown in the figure.
Fit the holder [C] to the air intake ducts [D].
Projections [E] and Holes [F]
Grooves [G] and Ribs [H]
Tighten:
Torque - Air Intake Duct Assembly Screws [I]: 1.5 N·m (0.15
kgf·m, 13 in·lb)
Turn the plug [J] so that ...