Ihave a 1989 harley sportster and i cant get the brakes to bleed..ive stripped the macter cylinder,cleaned and reassebled it..everything was as it should be going by the manual but the master cylinder dos'nt seem to be doing anything..even when ive removed the pipe from the caliper and capped the ends of with my fingers..its seems to create more of a vacum than pressure..any ideas greatly appreciated as the problem is driving me nuts..cheers..rich
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Re: Cant get brakes to bleed..
Easier to do from the bottom up.... (bubbles rise...right!)
You can get a pump at an auto parts store - I made one with a syringe and a peice of tubing. Attack the tube to the nipple at the caliper. Open the resavoir and fill the pump with fluid. Force it slowly up through the calpier, let it overflow the res. When the bubbles stop, close the nipple. If dual caliper, do the bottom, then the top. Close the system and pump the brakes a few time. that should do it
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lose the fittings at the master cylinder, you should have two of them , one for the front brakes and one for the rear, get a friend to push the brake pedal ( not too hard, be careful they may spay all over) ; and see if any fluid is coming out with his pedal down tight the fittings back with the pedal down,so you don't get any air in the lines. If nothing comes out you have a bad master cylinder.
Sounds like you need to change your Master Cylinder . This is the cylinder located below where the brake fluid goes. You stated no pressure and this is a symptom of this cylinder plunger going bad and not pushing fluid threw the lines. Remember to rate my solution
If you can't get any pressure on the rear brake, you have one of several possible problems. Either you have a brake fluid leak somewhere, your rear brake master cylinder is bad, or your bleeding procedure is not correct. Let's take the simple one first, your bleeding procedure. This is easy to get confused on but it must be done in an exact sequence. To bleed the brakes, first depress the brake lever and hold it down. Then, open the brake bleeder valve and allow the air and fluid to bleed out. Then, close the bleeder valve. Release the brake pedal and give the master cylinder time to refill though the small hole in the master cylinder reservoir. Repeat the procedure until you get a good firm pedal Do not allow the reservoir to run dry during this process. If you have a fluid leak, you should be able to see that. If the master cylinder is bad, it could be allowing the fluid to bypass the pressure cup inside of it. If this is the case, the master cylinder should be rebuilt. If this was done and it is not building pressure, the rubber pressure cup could have been installed backwards. It goes in with the cupped side facing the back of the master cylinder or the end where the brake line connects to the master cylinder.
A common problem with the single pot disc brake system. I find that I have to remove the bleed nipple completely before I can shift it and then the fun begins flushing the fresh fluid through and getting rid of the air. On a good day, I can spend up to 2 hours just on the front calliper! It's not you, it's the design. Keep on going, it will work in the end.
Rebuilding the master cylinder is relatively easy. Simply purchase a rebuild kit, take the master cylinder off the bike, Take the lever off and then most of the internal parts will simply come right out. With the internals out, you'll probably need to lightly hone the bore with a flex hone of the proper size. Lubricate the parts and install them just as they came out and reassemble the master cylinder. Then bleed the cylinder, hook up the brake hose on the bike and bleed the brakes at the caliper.
As far as I know, Harley never put a hydraulic clutch on a FXR. This may be some sort of aftermarket unit. You may can find bleeding instructions on the Internet by doing a search for the name on the system.
If that doesn't work, you may have to "reverse bleed" the system. Using a syringe or oil squirt can with brake fluid in it, open the bleed valves at the slave cylinder and put fluid "up" to the master cylinder on the handlebar.