roostingu 0 Posted February 17, 2009 Having some trouble with this one, any Idea's 2005 KTM 250 EXC I rebuilt my front brake mastercylinder last nite and I still have little or no front brake. I have had problems with this for some time, thinking it was the master cylinder because it seemed to act up only when it was cold, when warm it worked fine, in the cold back east I would heat up the MC with a heat gun before the ride and it would work fine as long as I kept using the brake. A couple weeks ago at McCain it would work if I pumped it and kept on it. So I did the rebuild and I now have less pressure than I did before, I bled it several times, I don't have a clue, unless the problem is in the line or the caliper? While bleeding the fluid moved through the line OK, maybe there is air somewhere I don't seem to be able to get it out? Share this post Link to post Share on other sites
bikeslut 1 Posted February 17, 2009 if you rebuilt the master, and sure you didn't botch the job, it is probably still air in the lines... my DRZ has a nasty bend in the line that is a pain... I disconnect the brake, and hang the whole line "inverted" overnight, then reconnect it the next day and powerbleed it... Share this post Link to post Share on other sites
roostingu 0 Posted February 17, 2009 OK I will try that, as far as botching the job it is possible I assembled as it should be lubing the cups with brake fluid , but while assembling I had a problem getting the sping in the lever to stay put and used the lever several times before adding fluid in order to get everything in its proper place, so I don't know if pumping it semi-dry would have ruined the cups? Share this post Link to post Share on other sites
paulmbowers 236 Posted February 17, 2009 BIG discussion thread on ktmtalk about this- titled something like "brake cure". It's pretty doubtful you ruined anything. I pressure bleed from the bottom up with a syringe and that typically does the trick, but there are a lot of nooks and crannies in which air will hide. Also, if you've been working it for a while, sometimes the the air will break up into little tiny bubbles. All references to Don Ho aside, you may wish to let it sit for a few hours and let those bubbles coalesce. Be sure to park the bike with the brake master as the highest point. Share this post Link to post Share on other sites
ozzy 0 Posted February 17, 2009 brakes just slow you down Share this post Link to post Share on other sites
Joliet 0 Posted February 17, 2009 Bleed from the bottom with a syringe works best for me. After you get the air out and get the lever so it will hold pressure, put a small bungee on the lever and hold pressure on it over night and usually that helps getting the small bubbles out so it feels solid. Good luck, Ken Share this post Link to post Share on other sites
roostingu 0 Posted February 17, 2009 BIG discussion thread on ktmtalk about this- titled something like "brake cure". It's pretty doubtful you ruined anything. I pressure bleed from the bottom up with a syringe and that typically does the trick, but there are a lot of nooks and crannies in which air will hide. Also, if you've been working it for a while, sometimes the the air will break up into little tiny bubbles. All references to Don Ho aside, you may wish to let it sit for a few hours and let those bubbles coalesce. Be sure to park the bike with the brake master as the highest point. Don Ho ? who does he ride for Share this post Link to post Share on other sites
roostingu 0 Posted February 18, 2009 Bleed from the bottom with a syringe works best for me. After you get the air out and get the lever so it will hold pressure, put a small bungee on the lever and hold pressure on it over night and usually that helps getting the small bubbles out so it feels solid. Good luck, Ken Ok well this is what I ended up doing, took the whole contraption off, put the mc in a vise, pushed fluid up from the caliper, back and forth several times also pistons in and out, then I took the mc apart again then reassembled it with it full of fluid. Still no good, I was going give up and decided to push the fluid up from the caliper again first with the piston half way out, then I pushed the pistons in as far as they would go,pushed the fluid from caliper to the mc, and this time it was a go, works great now. I don't understand I did this at least a half dozen times? The only thing I can think is that I made sure the pistons were completely withdrawn? Anyway I will zip tie the lever over nite just in case I think we got it this time. Thanks for all the input. Share this post Link to post Share on other sites
paulmbowers 236 Posted February 18, 2009 Tiiiny Bubbles In the wine, Make me happy, Make me feel fine Share this post Link to post Share on other sites
ozzy 0 Posted February 18, 2009 Don Ho ? who does he ride for John DeSoto Share this post Link to post Share on other sites
