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 DiscWater Temperature Sensor Inspection
Remove the water temperature sensor (see Water Temperature
Sensor Removal/Installation in the Fuel System
(DFI) chapter).
Suspend the sensor [A] in a container of coolant so that
the temperature-sensing projection [C] is submerged.
Suspend an accurate thermometer [B] with temperature
...
US, CA and CAL Models
1. Hold the water hose [A]. Insert the tab into the slot.
2. Hold the water hose [B]. Insert the tab into the slot.
3. Water Hose Fitting on Cylinder Head
4. Heat Insulation Rubber Plate
5. Run the crankshaft sensor lead and the oil pressure switch lead into the
slot, and hook the slot
on ...
Oil Cooler Installation
Replace the O-ring [A] with a new one.
Apply grease to the new O-ring.
Install the water hoses and hose clamps [A] as shown in
the figure.
Water Hose (About 300 mm, 11.8 in.) [B]
Water Hose (About 130 mm, 5.1 in.) [C]
Yellow Paint [D]
Tighten:
Torque - Water Hose Clamp S ...