2007 yz 450 f rear brake problem

1 reply to this topic
  • 88motohead88

Posted May 02, 2015 - 11:50 AM


I can't get the brakes to bleed. There is NO leaks and I can pump the brake all day with no pressure build up. I took apart the master cylinder and checked the rubber o rings on the inside of the cylinder. The spring and everything looked fine and like I said there's no leaks at all. The piston in the caliper will go in and out, it's not frozen or anything it just won't build pressure. Should I just by the rebuild kit? Are the o rings just not sealing anymore?

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  • gnatsum289

Posted July 25, 2015 - 04:25 PM


you could try one of those vacume brake bleeder kits they connect to the nipple and suck the fluid through but make sure you keep topping up the master or you will need to start again. I had a similar problem with a car a few years ago and was told the cylinder was cavitating but after vac bleeding it all worked fine

cheers paul

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