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
...
Fuel Injector Fuel Line Inspection
Remove:
Fuel Tank (see Fuel Tank Removal)
Air Cleaner Housing (see Air Cleaner Housing Removal)
Disconnect:
Primary and Secondary Fuel Hoses (see Fuel Hose Replacement
in the Periodic Maintenance chapter)
Do not remove the nozzle assy from the air cleaner housing.
Be sure to pla ...
Connecting 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 ...