Can someone help me out? I've been bleeding my brakes for forever. By hand, mity vac, a syringe from the caliper, and an air compressor attached to a vacuum bleeder and I'm still having the same problem. The front brakes get all hard but when I start moving the bike and applying pressure, it ALL goes away. Then when I'm in a certain position, some pressure is there, move a bit more, more pressure, move a but more, less pressure etc, but when I start moving without stopping, the pressure is all gone. What's the deal? No leaks anywhere, rebuilt the calipers (froze pistons) and master cylinder(just because) all 100% right. It's really ticking me off. Can someone help? My pads are good and rotors don't seem to be warped.

 

Put a zip tie on the lever to the grip over night , then bleed again, sometimes there is a bubble trapped right at the fitting of the master cylinder.

 

did you use the lube on the m/c piston when installing it? If dry you may have chaffed the seals. Also did you flush and blow dry with denatured alcohol?

 

You have a bent disc or both of them are bent. Lift the front of the bike and slowly turn the front wheel while watching the disc,when the bent portion of the disc passes through the caliper you will see it push the pistons back into their bores.That is the reason you have to pump the lever to regain pressure at the master cyl.

 

I put speed bleeders on mine, super easy to bleed them now.

 

Are you bleeding the brakes on the jiffy stand? If so it leaves an air pocket in the caliper because the bleeder isn't at the highest point of the caliper. Try turning the handle bars all the way to the right while on the jiffy stand, then repeat the bleeding process. It will be opposite of the way you turn the bars to lock the forks. This makes the caliper stand straight up and down. Hope it works

 

If you have bled all of the air out of the system and you lose brakes when you roll the bike,it has to be a bent rotor.

 

Seems like if a rotor were bent, you would a noticed it before you overhauled the calipurs. More likely you have bleeding problems. Try using a syringe of fluid hooked up to the bleed niple on the caliper and pump fluic uphell into the mastercyclinder. Sometimes it helps.

 

Just a thought.If it has air in the system,why is the lever firm,until the bike is rolled?But has to be pumped up after rolling,and will keep a firm lever until the bike is rolled again.

 

I'm bleeding on the jack so the bike is up right. And yes I lubed the seals and pistons in the caliper just as the manual said when installing. How can I check the rotors if they are warped?