My front brakes build pressure and the lever gets solid, but as soon as you move the bike it looses its pressure and the lever goes back to the bar. Then you have to pump it and it will go solid again. I bled the brakes and there is no leaks so im guessing it is a seal inside the master cylinder. Anybody ever come across this before.

 

sounds like warped rotors to me................

 

bent rotor...

 

I just put new rotors on, but if it was rotors the lever would move in and out not totaly lose all pressure.

 

it can feel as if it loses pressure if the rotor is bent so far that it pushes the piston back in to the caliper and then you have to pump it back out to get pressure

 

If a bent rotor is the case and it was pushing the piston back out i should be able to rotate my tire and there should be a gap in certain spots in the pads and the rotor. Is this right or am I just a total idiot

 

Bent rotor, 120% sure

 

Yes and No the rotors can be straight and the wheel can be bent. Just took a set out the box, put them on the bike same problem. Put the wheel in the balancer and sure enough the wheel was bent.

 

I had this problem.

1. You have a bent rotor. Replace it.
2. Rebuild the brakes.
3. Get a speed bleeder if you dont already.

 

it only has to move the pad back ever so slightly to give you a mushy feel at the lever

 

Everybody in this thread is correct listen to them

 

Try bleeding the breakes again. I had the same problem you described with my TTR. I would have to pump the lever a few times and it would feel solid. After riding a bit it would become totally loose again. I bled my brakes and used fresh fluid and never had that problem again.

 

hard to say man. spotting a warped rotor by eye is hard. ride the bike, apply the brake. if its choppy then im pretty sure its a belt/warped rotor.

 

+1

 

Thanks for all your help. I brought the wheel and rotors into the shop and put it on the balancer and sure enough it was the rotors lol. So I put my old set back on cause they were not warped as bad and tweaked the high spots out with a wrench. Now my brakes are working perfect. I dont think I wanted to believe it was the rotors cause I just bought them of an ebaystore and they were said to be straight and turns out they were shot.

 

some times they just get hit and they move in the rivets that hold them to the center part , i seen a set so far off the bike barely wanted to roll but after a little riding and hard braking they were good to go

 

Just saw a bent axle that did this but the rotors where also bent On a Busa

 

it happens man, unless you own a micrometer you'll never know 100%.