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 DiscExhaust System Identification
Exhaust Pipe Mark Position [A]
Premuffler Chamber Mark Position [A]
Muffler Body Mark Position [A]
Premuffler Chamber [A] with Hole [B] for Oxygen Sensor [C]
Honeycomb Type Catalyst Position [A]
Specifications
...
Passenger’s Seat Removal
Remove the passenger’s seat by inserting
the ignition key into the seat
lock, and turning it clockwise.
A. Seat Lock
B. Ignition Key
C. Passenger’s seat
D. Pull up
NOTE
When removing the passenger’s
seat, pull it up while turning the key. ...
Hub Bearing Inspection
Since the hub bearings are made to extremely close tolerances,
the clearance can not normally be measured.
NOTE
Do not remove any bearings for inspection. If any bearings
are removed, they will need to be replaced with
new ones.
Turn each bearing in the hub back and forth [A] while
checki ...