Topic: Brake Bleeding Problem

[KC_Northstar]

I Rebuilt the Master cylinder and caliper on my CB750 and never had any problem at all when it came time
to bleed them. I just got done rebuilding the MC and caliper on my wife's bike and cant get them to bleed.
I put fluid in the MS, opened the bleeder and I cant get any fluid to flow.  I loosened the brake line at the
MS and I don't even get one drop out there. I squeezed the brake lever and tied it down and left it about an hour.
No fluid going through at all.  Any ideas?

KC

[goldarrow]

Be sure the two tiny holes inside the reservoir are clean and clear

[KC_Northstar]

I'm pretty sure they are.   The brakes were working before the rebuild.  With the MC being 30+ years old, I figured
I better rebuild it.  I cleaned it real good and ran a wire down both holes.  Before I remove it again, I just want to
see if there is anything to try first.  I figure that with the brake line loosened at the MC and the lever tied in place
at half way that it should at least drip out there. Could it be air locked somehow in the MC?

[strynboen]

tryn to" suck" the flouid aut at the caliber air nippel..somtimes if it are total dry,it blokes for flouid to come dovn in MC piston champer(bore)..

[KC_Northstar]

OK, I took the MC off and mounted it in my bench vice.  I put my finger over the hose outlet.  When I push the lever I get pressure
on my finger and when releasing it vacuum, but no fluid.  So I figure one of the holes must be blocked.  So can I run a wire through
them again without taking it apart or would that possibly damage the rubber plungers??

[goldarrow]

Poke the holes with small wires be just fine

[cabrala]

Seems like you are heading down the right course of action. I had the same issue with my MC rebuild and found that bench bleeding the MC first was the difference. Once I got fluid pushing past my finger (blocking the outlet to the lines) I hooked everything back together and started the traditional bleeding process.

Best of luck once the holes are cleared.

[KC_Northstar]

Ok, so I reinstalled the MC and still had the same problem.  I figured it was time to try a power bleeder.  I don't have a power
bleeder or speed bleeder, so I made one up.  I stuck the hose from my shop vac into a glass jar and the small hose I use for bleeding
in there too.  I sealed the hoses and the top of the jar with duct tape.  Instant power bleeder.   That did the trick.  I'm not real sure
those holes in the MC were really clogged.  I think if I had just power bled it from the start that it would have worked. In any case
the front brakes are done and I have a solution for power bleeding in the future.

[Stev-o]

Good thinking.
My RD350 was impossible to bleed after a brake job, the power bleeder did the trick too for my too.

[mrfish2]

I was having trouble bleeding my new system as well. I ended up having to take it to a shop and let them bleed it with a vacuum system. Seems like this is generally the easiest and quickest way to go.

[Builder]

A way I have found to bleed when the system is dry, is to pull the lever just a tiny bit until a bubble or series of bubbles comes from the small holes inside the master reservoir. I call it tickling. Just tickle away and it bleeds the air out, and the air gets replaced by fluid. If you start squeezing the lever right away, it doesn't bleed the air out as well. It can take a while, but it usually works to "tickle" it.

[DWS]

might try this

[krusty]

A way I have found to bleed when the system is dry, is to pull the lever just a tiny bit until a bubble or series of bubbles comes from the small holes inside the master reservoir. I call it tickling. Just tickle away and it bleeds the air out, and the air gets replaced by fluid. If you start squeezing the lever right away, it doesn't bleed the air out as well. It can take a while, but it usually works to "tickle" it.

+1. Works every time for me.