HYOSUNG 2010 ST7, Service Manual

Page: 38 / 298

PERIODIC MAINTENANCE 2-20
①
AIR BLEEDING OF THE BRAKE
FLUID CIRCUIT
Air trapped in the brake fluid circuit acts like a cushion to
absorb a large proportion of the pressure developed by
the master cylinder and thus interferes with the full brak-
ing performance of the brake caliper. The presence of
air is indicated by sponginess of the brake lever and
also by lack of braking force. Considering the danger
to which such trapped air exposes the machine and
rider, it is essential that, after remounting the
brake and restoring the brake system to the normal
condition, the brake fluid circuit be purged of air in the fol-
lowing manner :
Fill the master cylider reservoir to top of the inspec-
tion window. Replace the reservoir cap to prevent dirt
from entering it.
Attach a hose
to the air bleeder valve, and insert
the free end of the hose into a receptacle.
Bleed air from the brake system.
Squeeze and release the brake lever several times
in rapid succession and sqeeze the lever fully with-
out releasing it. Loosen the bleeder valve by turn-
ing it a quarter of a turn so that the brake fluid runs
into the receptacle, this will remove the tension of
the brake lever causing it to touch the handlebar
grip. Then, close the air bleeder valve, pump and
squeeze the brake lever, and open the valve.
Repeat this process until the fluid flowing into the
receptacle no longer contains air bubbles.
Close the air bleeder valve, and disconnect the hose.
Fill the reservoir with brake fluid to the upper line.
Bleed the rear brake s air with the same manner of
front brake.
LOWER
NOTE
While bleeding the brake system, replenish the
brake fluid in the reservoir as necessary. Make
sure that there is always some fluid visible in the
reservoir.
CAUTION
Handle brake fluid with care : the fluid reacts chemi-
cally with paint, plastics, rubber materials, etc.
Front brake caliper air bleeder valve
: 6 ~ 8 N m (0.6 ~ 0.8 kgf m)
Rear brake caliper air bleeder valve
: 6 ~ 8 N m (0.6 ~ 0.8 kgf m)