Suzuki UF50 Service Manual page 22

2-10 PERIODIC MAINTENANCE
AIR BLEEDING 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 cyl-
inder, thus interferes with the full braking 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 restor-
ing the brake system to the normal condition, the brake fluid
circuit be purged of air in the following manner:
Fill the master cylinder reservoir to the upper end of the in-
spection window. Replace the reservoir cap to prevent dirt
from entering.
Attach a hose to the caliper bleeder valve, and insert the free
end of the hose into a receptacle.
Bleed air from the bleeder valve.
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 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 handle-
bar grip. Then, close the valve, pump and squeeze the lever,
and open the valve. Repeat this process until the fluid flowing
into the receptacle no longer contains air bubbles.
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.
Close the bleeder valve, and disconnect the hose. Fill the res-
ervoir with brake fluid to the top of the inspection window.
Air bleeder valve: 7.5 N·m (0.75 kgf-m)
Handle the brake fluid with care: the fluid reacts chemi-
cally with paint, plastics, rubber materials, etc.