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Hi all, and thank you for reading this thread, and hopefully replying with assistance.

I have been racing a GSXr K6 for a while, and last season swapped the master cylinder for a Brembo RCS19, plus SBS Dual Carbon brake pads. The results were amazing, although I have always felt the brake lever to have too much travel.

Over the winter I have rebuilt the calipers (pistons, and seals). This was professionally done, with the calipers being pressure tested. All was fine.

I am having problems with the bleeding process. The calipers seem fine, with only brake fluid being passed from the bleed nipples.

The master cylinder is another thing. Air bubbles constantly flow from the bleed nipple. With the reservoir always full of brake fluid, and the bleed nipple open, by simply using a gravity feed, air bubbles will stream out of the bleed nipple (almost constantly). Strangely, with the bleed nipple value closed, air bubbles will still come through the clear plastic tubing. The brake level will come back to the bars. I have been at this for hours, and the air just keeps on coming.

Do I need to simply persevere, or is there a problem?

Thanks
 

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Hi all, and thank you for reading this thread, and hopefully replying with assistance.

I have been racing a GSXr K6 for a while, and last season swapped the master cylinder for a Brembo RCS19, plus SBS Dual Carbon brake pads. The results were amazing, although I have always felt the brake lever to have too much travel.

Over the winter I have rebuilt the calipers (pistons, and seals). This was professionally done, with the calipers being pressure tested. All was fine.

I am having problems with the bleeding process. The calipers seem fine, with only brake fluid being passed from the bleed nipples.

The master cylinder is another thing. Air bubbles constantly flow from the bleed nipple. With the reservoir always full of brake fluid, and the bleed nipple open, by simply using a gravity feed, air bubbles will stream out of the bleed nipple (almost constantly). Strangely, with the bleed nipple value closed, air bubbles will still come through the clear plastic tubing. The brake level will come back to the bars. I have been at this for hours, and the air just keeps on coming.

Do I need to simply persevere, or is there a problem?

Thanks
Always suggest to tie the lever against the handlebar, with wire or cable tie ( at least overnight ). To allow all the air to escape, sometimes it just gets trapped and needs time to escape.
 

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I have seen the zip tie done and apparently works great!!! On anotger note, are the bleeder valves special or can you get them at an auto parts place??? The nipple you loosen to bleed the brakes at the caliper... Thanks in advance for any answer to my ignorance...
 

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It is possible to introduce air through the threads of the nipple. This could be the issue. Keep the lever pulled in overnight will let the air go back up. Then try again. Perseverance is key. Speed bleeders have a thread sealant that i bought with the nipples. The sealant could fix what’s happening.
 

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Always suggest to tie the lever against the handlebar, with wire or cable tie ( at least overnight ). To allow all the air to escape, sometimes it just gets trapped and needs time to escape.
Ah crap, I forgot to do this a couple weeks ago! I was standing there knowing I forgot something and couldn’t figure out what it was! Thanks!!!


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I have a vacuum pump and I hate seeing those little bubbles too. I agree it could be happening in the bleed valve threads or from around the vacuum fitting...I feel more confident pumping the brake lever old school style and opening and closing the bleed valve. I’m able to reach the left caliper doing this...to each their own on this one!


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Hi,
You probably got your brakes fixed already. but the next time you try bleed your brakes, try to bleed the master cylinder by loosening banjo bolt and bleed it there. If you get it bleed good it will start pushing more fluid and bubbles out of the banjo bolt and washers. Now bleed it at the caliper. If that doesn't work, try to get the master cylinder level, and take the banjo bolt and washers out and put your finger on the hole on the master cylinder and bleed the master cylinder. When you get it bleed good,when you squeeze the lever it will have a lot of pressure on your finger and fluid will squat out all over the place. (Hopefully you already have your paint covered) put the banjo bolt and washers and line on master cylinder and tighten them. Now go to the caliper and bleed it there, you should start building up some lever pressure.
Hope this helps you, or someone!!!
 
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