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Brake bleed

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I changed a brake line and now I am having problems getting the brake fluid to fill the line and the caliper. I pump and pump, but the fluid level in the master cylinder does not move. How do I do this??

Jimbo

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Did you upgrade to stainless steel? Anyhow...

It'll probably be easier if you prime your brake line first. Motorcycle calipers and brake master cylinders are low volume, unlike your car.

1. Disconnect the brake line at the master cylinder..pour fluid directly (and slowly) into the line.

2. Make sure the bleed tap is loose on the brake itself.

3. Reconnect line to master cylinder.

4. With bleeder still loose, slowly squeeze brake lever.

5. After each squeeze (compression of the brakes) don't release the lever until you have the bleeder nipple tight again.

6. Release brake lever after tightening bleed nipple.

7. Repeat 4, 5, 6, opening bleed nipple after squeezing lever (allowing some pressure to build in line before opening nipple).

8. Having a helper, well, helps...

9. Continue until no more bubbles come out of nip at brake end...

10. Wish for the simplicity of brake cables (the old mechanical style) as you clean up the giant puddle of DOT4 brake fluid. :cry:

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Seriously, there is no "magic" to gravity bleeding. It's hit or miss and takes WAY too much effort on a bike. Even if it does pump up, you have to get lucky to get rid of the air. Bleed from the bottom!! It costs $6 (for the oil can) and takes <5 minutes. I don't know why anyone would even mess with pumping/opening-closing the bolt/tying the lever to the bar overnight??&%$#@!--just do it from the bottom!!

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I don't know why anyone would even mess with pumping/opening-closing the bolt/tying the lever to the bar overnight??&%$#@!

This is not good for bleeding the system. After you bleed the system as much as possible, tying the lever down removes small bubbles and tightens the system up as much as possible. The more you pump brake fluid under pressure, the worse the aeration.

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Jim_bo said the fluid in the master cylinder didn't move. So this doesn't sound like a typical bleeding issue. If you open up the bleed valve on the caliper and pump the brake lever, fluid should dump out the bleed valve and then suck it from the reservoir. Maybe you didn't have the bleed valve open far enough. Maybe the rubber cap got eaten by a rock and the valve is packed with dirt. It is real easy with little force to pump the brake lever when the bleed valve is open. So if you have a lot of pressure and nothing comes out, maybe the valve is clogged. Am I way off base here, did I misunderstand, you really can't even get fluid to flow thru the system?

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Sound EXACTLY like a typical bleeding issue. Sometimes it's tough to get ANY pressure to build. Doesn't hurt to clean the rubber in the master cylinder but I'll bet if you fill it from the bottom, you won't have to mess with it. I've been there. I know how to gravity bleed just would rather not mess with it. Since I've been backbleeding, I haven't had to do anything to get the air out (tying the lever to the bar)--if you need that, you're doing it wrong. I'll just say it one more time...back bleed and you'll wonder what the hell you were thinking before!

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Very simple. You'll need an old-style oil can (must be new)-You can find these at ACE or any local hardware store. They have the thumb pump built into the lid-cost=$6.00

You'll also need a small length (1 foot is plenty) of tubing that will snugly fit over the nipple of the oil can (20 cents)-And dot4 brake fluid

1. Remove the reservoir lid.

2. Fill oil can with brake fluid

3. Attach one end of tube to the oil can nipple and pump until fluid overflows (forcing all air out of the tube)--then attach other end to brake caliper bleeder nipple (there should be a rubber cap over it--remove cap).

4. Pump fluid up the line until reservoir is full.

5. Replace bleeder valve cap and reservoir lid--make sure lever adjustment is correct.

That's it. Once you do it this way, you'll never look back. From now on, it will take you 5 minutes to replace fluid/bleed brakes

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