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 DiscThrottle Body Assy Holder Installation
Be sure to install the new O-rings [A].
Using a high flash-point solvent, clean off any oil or dirt
that may be on the silicone sealant coating area. Dry
them with a clean cloth.
Apply silicone sealant to any two positions of the new O
-ring.
Sealant - Liquid Gasket, TB1211F: 92104-0 ...
Payload and Tire Pressure
Failure to maintain proper inflation
pressures or observe payload limits for
your tires may adversely affect handling
and performance of yourmotorcycle
and can result in loss of control. The
maximum recommended load in addition
to vehicle weight is 180 kg (397 lb),
including rider, passenger, ...
Swingarm Bearing Removal
Remove:
Swingarm (see Swingarm Removal)
Collar [A]
Oil Seals [B]
Sleeve [C]
Circlip [D] (Right Side)
Special Tool - Inside Circlip Pliers: 57001-143
Remove the ball bearing and needle bearings.
Special Tool - Oil Seal & Bearing Remover [A]: 57001-1058
...