2-13
PERIODIC
MAINTENANCE
AND
TUNE-UP
PROCEDURES
BLEEDING
AIR
FROM THE
BRAKE
FLUID
CIRCUIT
Air
trapped in the
fluid
circuit acts like a cushion
to
absorb a
large
proportion
of
the
pressure
developed
by
the master cyl-
inder
and
thus interferes with the full braking performance
of
the brake caliper. The
presence
of
air
is
indicated by "spongi-
ness"
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
ofair
in the following manner:
• Fill up the master cylinder reservoir
to
the upper
end
of
the
inspection window
(for
front
brake)
and
upper line
(for
rear
brake). 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.
NOTE:
When bleeding the air, always start with the inboard valve, and
then the outboard 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 flow-
ing
into
the receptacle no longer contains air bubbles.
NOTE:
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 upper
end
of
the inspection
window
(for
front
brake)
and
upper line
(for
rear brake).
•
Rear
brake: Differences between
front
and
rear
are
that
the master cylinder
is
actuated by a pedal.
Bleeder valve tightening torque: 6 - 9 N·m (0.6 - 0.9 kg-m)
CAUTION:
Handle the brake
fluid
with
care: the
fluid
reacts chemically
with
paint, plastics, rubber materials, etc.
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