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 DiscClock
To adjust hours and minutes, do the
followings while the motorcycle is at a
stop.
Turn the ignition switch to “ON”.
Display the odometer in the multifunction
display. Refer to the “Multifunction
Display” item in this section.
Push the lower button for more than
2 seconds. Bot ...
Connecting Rod Bend Inspection
Remove the connecting rod big end bearing inserts, and
reinstall the connecting rod big end cap.
Select an arbor [A] of the same diameter as the connecting
rod big end, and insert the arbor through the connecting
rod big end.
Select an arbor of the same diameter as the piston pin
and ...
Thermostat Inspection
Remove the thermostat (see Thermostat Removal).
Inspect the thermostat valve [A] at room temperature.
If the valve is open, replace the thermostat with a new
one.
To check valve opening temperature, suspend the thermostat
[A] in a container of water and raise the temperature
of ...