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 DiscOil Pump Removal
Remove:
Coolant (Drain, see Coolant Change in the Periodic
Maintenance chapter)
Engine Oil (Drain, see Engine Oil Change in the Periodic
Maintenance chapter)
Sidestand Switch Lead Connector [A] (Disconnect)
Bolt [B] and Water Pipe [C]
Water Pump Cover Bolts [D]
Water Pump Cover [E ...
Intake Air Pressure Sensor #1 Output Voltage Inspection
Measure the output voltage at the intake air pressure sensor
#1 in the same way as input voltage inspection, note
the following.
Disconnect the intake air pressure sensor #1 connector
and connect the measuring adapter [A] between these
connectors.
[B] Main Harness
[C] Intake Air Pressu ...
Daily Checks
Check the following items each day before you ride. The time required is
minimal,
and habitual performance of these checks will help ensure you a safe, reliable
ride.
If any irregularities are found during these checks, refer to the Maintenance
and
Adjustment chapter or see your dealer fo ...