Honda CB1000 Owner's Manual page 24

Brake fluid must be added to the reservoir
whenever the fluid level begins to reach the
LOWER level mark (1). Remove the seat
(page 36 ) and rear cowl (page 38). Remove
the screws (2), reservoir cover (3),
diaphragm plate (4) and diaphragm (5).
Fill the reservoir with DOT 4 BRAKE
FLUID from a sealed container up to the
UPPER level mark (6). Reinstall the
diaphragm, diaphragm plate and cover.
Tighten the screws securely.
Other Checks:
Make sure there are no fluid leaks. Check
for deterioration or cracks in the hoses and
fittings.
18
(6)
(2)
(1) LOWER level mark (4) Diaphragm plate
(2) Screw
(3) Reservoir cover
(5) Diaphragm
(6) UPPER level mark