Master Cylinder Assembly
Before assembly, clean all parts including the master
cylinder with brake fluid or alcohol.
Except for the disc pads and disc, use only disc
brake fluid, isopropyl alcohol, or ethyl alcohol, for
cleaning brake parts. Do not use any other fluid for
cleaning these parts. Gasoline, engine oil, or any
other petroleum distillate will cause deterioration of
the rubber parts. Oil spilled on any part will be diffi-
cult to wash off completely, and will eventually de-
teriorate the rubber used in the disc brake.
Apply brake fluid to the removed parts and to the inner
wall of the cylinder.
Take care not to scratch the piston or the inner wall of the
Tighten the brake lever pivot bolt and pivot nut.
Torque - Brake Lever Pivot Bolt: 1.0 N·m (0.1 kgf·m, 9 in·lb)
Brake Lever Pivot Nut: 5.9 N·m (0.60 kgf·m, 52
Master Cylinder Inspection (Visual Inspection)
Disassemble the master cylinder (see Master Cylinder
Check that there are no scratches, rust or pitting on the
inner wall of the master cylinder [A] and on the outside of
the piston [B].
If the master cylinder or piston shows any damage, re-
Inspect the primary [C] and secondary [D] cups.
If a cup is worn, damaged, softened (rotted), or swollen,
the piston assembly should be replaced to renew the
If fluid leakage is noted at the brake lever, the piston as-
sembly should be replaced to renew the cups.
Check the dust cover [E] for damage.
If it is damaged, replace it.
Check that the relief [F] and supply [G] ports are not
If the relief port becomes plugged, the brake pads will
drag on the disc. Blow the ports clean with compressed
Check the piston return spring [H] for any damage.
If the spring is damaged, replace it.