Bleeding master cylinder Grrrrr...

[luvmyGPz]

OK Gang,
I rebuilt my master cylinder yesterday. It needed it too. The piston was all corroded and was sticking. The bore was perfect so I was able to replace the piston and seals, paint it and get it back on. The problem is I can't get all the air out of the system. I have run about 1/2 a can of brake fluid thru it and it is still pumping out air. I am using a vacuum bleeder if that makes any difference. I don't think it is the master cylinder. I slowly pulled the lever in repeatedly until the bubbles stopped. I have bled these before without these problems. I am thinking I have a leak somewhere that is allowing air in but not fluid out. Is that possible? I did not rebuild the calipers if that makes a difference. All the air seems to be coming out of the right caliper.
TIA,

[A2rider]

If you can wait, buy a pair of Speed Bleeders, people swear by them. If not, keep tapping your brake lines, get a 12 pack and keep pumping away!

[luvmyGPz]

Thanks A2Rider,
I uses speed bleeders on my cars but with a vacuum bleeder it shouldn't make any difference, should it?.

[A2rider]

You can't get ANY pressure on the lever?

[A2rider]

Here are some sites, in case you think you missed something.

Bleeding Motorcycle Brakes - webBikeWorld

Motorcycle Brake Maintenance Guide - Motorcycle Maintenance Guide

Motorcycle Repair: brake bleeding

[luvmyGPz]

Yeah, I get pressure but it feels a little spongy and air bubbles keep coming out of the end. The rear brakes bled up fine.

[A2rider]

Originally Posted by luvmyGPz

Yeah, I get pressure but it feels a little spongy and air bubbles keep coming out of the end. The rear brakes bled up fine.

PM Greenisbest, he's a good mechanic and is online right now.

[gpzrider]

Depending on how loose you have the bleeder valve, air could be getting pulled past the threads of the bleeder and not coming from the lines at all.

[WeBeToyz]

Originally Posted by gpzrider

Depending on how loose you have the bleeder valve, air could be getting pulled past the threads of the bleeder and not coming from the lines at all.

If using a vacuum bleeder you should wrap teflon tape around the threads of the bleeder screw to minimize this problem. Make sure you wrap just around the threads and don't cover the hole.

When bleeding and you see a steady stream of small bubbles coming out of (looks almost like a solid line) then the air is bled out of the line. The small bubbles are caused by the air that is passing through the threads of the bleed screws.

I don't remember where the bleed screws are on the calipers of this bike, but in times past I have taken the calipers off the bike and angled them to get the bleed screw at the highest possible point, otherwise air can get trapped at the top of the caliper. If you do this remember to put a piece of wood (or spacer of some sort) inbetween the pistons so they don't pop out of the housings if you are bleeding by squeezing the brake lever.

For the record, I don't swear by speed bleeders at all. I don't want to trust my brakes to a spring-loaded ball bearing...