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 DiscSprocket Wear Inspection
Visually inspect the engine and rear sprocket teeth for
wear and damage.
If the teeth are worn as illustrated, replace the sprocket,
and inspect the drive chain wear (see Drive Chain Wear
Inspection in the Periodic Maintenance chapter).
Worn Tooth (Engine Sprocket) [A]
Worn Tooth (Rear ...
Headlight Aiming Adjustment
NOTE
Do not turn the bolts [A] because the reflector in the
headlight comes off.
(In the photo, the headlight unit has been removed for
clarity.)
NOTE
The left adjuster [A] and right adjuster [B] can move the
direction of the headlight beam to up, down, left and
right by turning each a ...
Crankshaft Sensor Inspection
Disconnect the crankshaft sensor lead connector (see
Crankshaft Sensor Removal).
Set the hand tester [A] to the × 10 Ω range and connect it
to the crankshaft sensor lead connector [B].
Special Tool - Hand Tester: 57001-1394
Crankshaft Sensor Resistance
Connections:
Meter (+ ...