Yamaha YTZ250S 1986 Service Manual page 86

Bleeding the brakes
WARNING:
If the brake system is disassembled or if
any brake hose has been loosened or
removed, the brake system must be bled
to remove air from the brake fluid. If the
brake fluid level is very low or brake
operation is incorrect, bleed the brake
system. Failure to bleed the brake system
properly can result in a dangerous loss of
braking performance.
1. Add proper brake fluid to the reservoir.
Install the diaphragm, being careful not
to spill or overflow the reservoir.
2. Connect a clear plastic tube, 4.5 mm
(3.16 in) inside diameter, tightly to the
caliper bleed screw. Put the other end of
the tube into a container.
3. Slowly apply the brake lever several
times. Pull in the lever. Hold the lever in
this "on" position. Loosen the bleed
screw. Allow the lever to travel slowly
toward its limit. When the limit is reach-
ed, tighten the bleed screw. Then release
the lever.
4. Repeat the above procedure until all air
bubbles are removed from the system.
Bleed screw tightening torque:
6 Nm (0.6 m'kg, 4.3 ft·lb)
4-7
NOTE: ______________________ _
If bleeding is difficult, it may be necessary to
let the brake fluid system stabilize for a few
hours. Repeat the bleeding procedure when
the tiny bubbles in the system have settled
out.