quick brake question

[wifarmboy]

So Im building a street fighter bobber thing out of a yamaha virago i got a set of complete levers off fleabay master cylinder and all well i can't get any pressure out of the front brake even when i take the caliper off it will move the plunger but when you let off it will go back to where it was. make sense? i have tried every trick in the book to bleed it thinking it just air but still no luck. also there's not much fluid getting pushed through the line. is there a bench bleed i need to do or need a bigger master?
does anyone have a master for 7/8 bar flat mount they could get rid of cheap.
thanks

 

[wifarmboy]

No one??

 

[d_adams]

Bench bleeding can be done with a vise (to hold the M/C) and your thumb over the outlet for the line with nothing else hooked up. Squeeze the lever with your thumb in place, it should easily push past it and dribble (possibly spray) out. Once it's verified that the M/C works, hook everything else up on the bench, assuming it's easy enough to mount on the bike all hooked up. Some bikes you can get away with it, some you can't. Put something solid in the caliper between the pads, then start pumping the fluid in. Leave the caliper lower than the M/C.

 

[Cooter]

Look in your M/C. if the tiny hole (inside the hole) is blocked, it will do what you describe. use a small piece of wire to clear it and make sure.
And take you time! after you close the bleeder and release the lever....wait........................... then continue.

Sometimes just gravity bleeding works for stubborn systems. Make sure the m/c is full and crack the bleeder until it gets low. doing that twice should be plenty.

Good luck! for being such simple systems, they sure can be a PITA!

 

[wifarmboy]

Ill have to try the bench bleed. i have let it sit cracked for a couple days with the resivour full and still no luck. And ill take a look at the little holes make sure there clear
thanks

 

[buellybill44]

If nothing else is working I would give vacuum bleeding a shot.. Ive gotten some really stubborn clutch master/slave cylinders to bleed out perfectly with a little mightyvac setup. Good luck man!

 

[Cooter]

You have cracked the bleeder for DAYS!?! If you aren't getting flow from the bleeder (without squeezing the lever), the the M/C port must be clogged. How else can fluid not flow down? Let us know.

 

[wifarmboy]

Ya iv had it cracked with a hose on the bleeder up about 6 inches and a adapter on the mc to hold like a qt .. the bleeder open just enough for like 2 drips a min. tried a vac bleed. i just wonder if the mc doesn't push enough fluid ..