HYOSUNG RX 125 Service Manual page 25

AIR BLEEDING THE BRAKE FLUID CIRCUIT
Air trapped in the fluid circuit acts like a cushion to
absorb a large proportion of the pressure devel-
oped by the master cylinder and thus interferes
with the full braking performance of the caliper
b r a k e . T h e p r e s e n c e o f a i r i s i n d i c a t e d b y
"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 should be purged of air in the
following manner.
● Fill up the master cylinder reservoir to the
"HIGH"level line. Replace the reservoir cap to
prevent entry of dirt.
● Attach a pipe to the caliper bleeder valve, and
insert the free end of the pipe into a receptacle.
Bleeder valve : 6~9 N∙m (0.6~0.9 kg∙m)
● Squeeze and release the brake lever several
times in rapid succession, and squeeze the
lever fully without releasing it. Loosen the
bleeder valve by turning quarter of it 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 valve, pump and squeeze the lever,
and open the valve. Repeat this process untill
the fluid flowing into the receptacle no longer
contains air bubbles.
CAUTION
Replenish the brake fluid reservoir as necessary
while bleeding the brake system.
Make sure that there is always some fluid visible
in the reservoir.
● Close the bleeder valve, and disconnect the
pipe.
Fill the reservoir to the "HIGH"level line.
WARNING
Handle the brake fluid with care : the fluid
reacts chemically with paint, plastics, rubber
materials, etc.
PERIODIC MAINTENANCE 2-12