Mityvac MV8020 AUTOMOTIVE BRAKE BLEEDING KIT - Manual (Page 8)

Page Number - 8 Form 824381
MOTORCYCLE BLEEDING PROCEDURE
Before bleeding the system, ensure that:
1) The brake caliper pistons are free to move
within the calipers.
2) The master cylinder piston is free to return to
the end of its stroke, and
3) Inspect the line to ensure that all fittings are tight.
FRONT BRAKE
1) Pump brake lever to seat caliper pads
against rotor.
2) Cover gas tank with plastic protective sheet
if using DOT 3 fluid (not necessary if using
DOT 5 fluid).
3) Remove master cylinder reservoir cap and
fill reservoir.
4) Select the appropriate adapter(s). The L-shaped
universal adapters should fit snugly over the brake
bleeding fitting in order to seal properly. The
tapered adapters fit inside the thru-hole of fitting
and will generally seal well when inserted tightly
with a pressing and twisting motion. Attach adapter
to reservoir hose.
5) Pump several times to create vacuum. Crack
bleeder valve with box wrench, extracting fluid into
reservoir. (Stop and add fluid when master cylinder
begins to get low. Do not allow air to enter line.).
At this point, all air should be out of system and
line full of fluid. (Note: if air is entering the pump
hose from around bleeder fitting, remove bleeder
fitting and apply Teflon tape to threaded portion
of bleeder screw only. This will prevent air seepage
around threads of bleeder screw.)
6) While maintaining vacuum on the pump line,
tighten bleeder fitting.
7) Top off reservoir and reinstall cover. Check brake
by pumping lever several times. Pedal should have
a positive, solid feel. If not, repeat bleeding process
as more air may have entered the system. Inspect
line to ensure all fittings are tight. If brake still feels
slack, consult a service technician.
For dual disc front brakes, repeat bleeding process
as though there are two separate systems.
REAR BRAKE
Removing all air from the rear brake line is the
same as for the front. The rear brake reservoir is
usually located beneath one of the side covers.
1) Remove the master cylinder cap and fill
to near full.
2) Attach the pump hose to the bleeder fitting and
pump the handle several times to create a vacuum.
3) Crack the bleeder with a box wrench. Because of
the short line, most of the air should be evacuated
the first time.
4) By closing the valve and repeating the process,
all of the air should be eliminated from the system.
Stop and add more fluid when master cylinder
gets low.
5) Top off and recap the reservoir.
TROUBLESHOOTING
1) If, after bleeding procedure, the brake continues
to be unresponsive, you may have water in the
system, in which case it will need to be disassembled
and cleaned by a qualified service technician.
2) If the brake squeaks slightly after bleeding,
the disc and pads must be cleaned.
3) Although DOT 3 fluid is recommended by
most manufacturers, it has a tendency to collect
moisture, which causes the common discoloration
you see - and that means decreased efficiency.
DOT 5 is silicone based and does not have the same
tendency to collect moisture. It also has a higher
tolerance. DOT 5, however, is not always easy to
find and the two types of fluid must not be mixed.
4) Rubber hoses are supplied stock on most
motorcycles, but they have a tendency to expand,
which may result in a spongy brake feel after a lot
of riding. Braided steel line will not expand like this.
BRAKE BLEEDING