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 DiscShift Fork Guide Pin/Drum Groove Wear Inspection
Measure the diameter of each shift fork guide pin [A], and
measure the width [B] of each shift drum groove.
If the guide pin on any shift fork is less than the service
limit, the fork must be replaced.
Shift Fork Guide Pin Diameter
Standard: 6.9 7.0 mm (0.272
0.276 in.)
Service Limit: ...
Front Master Cylinder Installation
Apply silicone grease to the sliding surface of the brake
lever pivot bolt.
Tighten:
Torque - Brake Lever Pivot Bolt: 1.2 N·m (0.12 kgf·m, 11
in·lb)
Brake Lever Pivot Bolt Nut: 5.9 N·m (0.60 kgf·m,
52 in·lb)
Assemble the reservoir [A] and the bracket [B] as shown
in the figu ...
Coolant Change
WARNINGCoolant can be extremely hot and cause
severe
burns, is toxic and very slippery. Do not remove
the radiator cap or attempt to change the coolant
when the engine is hot; allow it cool completely.
Immediately wipe any spilled coolant from tires,
frame, engine or othe ...