brakes?

[garyrc]

yesturday i filled my front master cylinder eith fluid. no i notice fluid leaking from the master cylinder resevor . did i over fill it and if so would an over fill cause leaking?

[garyrc]

yesturday i filled my front master cylinder with fluid. now i notice fluid leaking from the master cylinder resevor . did i over fill it? and if so ,would an over fill cause leaking?

[DiverRay]

Gary;
If you didn't leave room for air and the rubber in the top, that would explain the leak. When filling the master, try not to get the fluid level above the window.

[garyrc]

thanks diverray.
so once the level comes down will it stop?

[DiverRay]

It should, but if it's that overfull, I would take the cap off and remove a little fluid.

[garyrc]

ok thanks for the advice

[Chaluska]

lol, be lucky yours even took fluid.. im still working on mine, and the master cylandar (rear one in particular), absolutly WILL NOT accept fluid flow..... no matter how much i pump it.. i rebuilt it, and cleaned it thurouly (sp).. ive been reading, and i think ill lhave to just leave it pressed in overnight, and let the gravity take care of it..

[DiverRay]

What you needed to do was "bench bleed" the cylinders. This involves adding some fluid, and then push slowly in on the piston. When it's in all the way, plug the line going too the caliper and release the piston. This will get rid of any air, and keep it from getting an "air lock".
That is probably what you have going on now. You may be able to remove the brake line, and use your finger to block off the line as you let the piston back out.

[xj11john]

Hey Diverray

I cleaned my front master and caliper and was trying to bench bleed it and the piston would not move back unless i stuck a screw driver in the hole where the line hooks up- and pushed it back, and same thing on the back side the only way it would move is if I pushed it. What puzzles me is it would work before I took everything apart and cleaned it. Do you think it is because the unit had the pressure already there when it was together it would work? (even though the caliper piston seemed stuck when I had it apart, and I used a grease gun to push the piston back out) I hope I dont have to rebuild it since I have been on it for a couple days and would like not to have to wait on shipping and the rebuilding itself-I'm ready to just ride it again. any input would be appreaciated, and good luck Gary on yours, I took my rear master apart and cleaned the piston, and bore but it seemed easier to do than the front, I'm afraid I'll mess up the rubber boot if I take it apart?? well we'll see what happens tomorrow. see ya'll..

[DiverRay]

Did you replace the rubber parts in the MC? If you cleaned everything up, but didn't put in new seals, that is probably a BIG part of your problem.
When you reassembled the MC, did you use plenty of new brake fluid to lub the seals and piston? Lastly, are you sure you didn't have a seal lip "roll over" when you put the piston back in? Some times (a lot of times!!) the seal lip will catch when you are inserting the piston back into the bore. If this happens, the piston will be VERY stiff, and it will not seal!
You may want to pop the piston back out, check the cup edge for a "line" where is may have folded over, and CAREFULLY reinsert the piston.
Good luck.
Ray

[xj11john]

seal lip rollover

Ray, that is what it sounds like I have a seal lip rollover, but I didnt take the master cylinder apart because I didnt have the rebuild kit, I did attempt to take the clip or ring off the rubber, but a piece of it broke off, so I stopped there.

Today or monday (it is 9 am here) I will go to my friends that has a bike junk yard and see if that other yamaha (prob xj600-750) and see if that front mc piston will return when pushed, if it will I may purchase it, or I'll order a kit. Thanks for the input.

[xj11john]

Turned out to be a swelled dust boot, just changed the boot out and works fine now