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 DiscSpecial Tools
Fork Oil Level Gauge:
57001-1290
Vacuum Gauge:
57001-1369
Hand Tester:
57001-1394
Throttle Sensor Setting Adapter #1:
57001-1400
Peak Voltage Adapter:
57001-1415
Needle Adapter Set:
57001-1457
Throttle Sensor Setting Adapter:
57001-1538
Measuring Adapter:
57001-1700
...
Air Intake Duct Removal
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal in the Frame chapter)
Meter Bracket (see Meter Unit Removal/Installation in
the Electrical System chapter)
Immobilizer Amplifier [A] (Equipped Models) (see Immobilizer
System Parts Replacement in the Electrical System
...
Air Cleaner
A clogged air cleaner restricts the engine’s
air intake, increasing fuel consumption,
reducing engine power, and
causing spark plug fouling.
This motorcycle’s air cleaner element
consists of a wet paper filter, which cannot
be cleaned.
The air cleaner element must be replaced
in acco ...