crashmonkey Posted February 19, 2012 Report Share Posted February 19, 2012 (edited) First off I have done a search and read a lot of the threads on bleeding brakes. This is the front brake, so far I have: Presssure bled both ways. gravity bled. Bled with the engine on (vibration can help) left for 24 hours for any air in the system to disipate. bled with the caliper of so you can move it around to help dislodge and trapped air. I am sure there is no air in there!! I do have pressure, it just seems a little spongy, the system starts to build pressure almost when the piston has only moved about 3mm.Btw the piston in the m/c is returning fully, and has a brand new seal kit fitted. It almost seems as though the pistons move out as pressure builds in the system, then they move back as well, only a little but enough cause a problem? As always thanks Edited February 19, 2012 by CrashMonkey Quote Link to comment Share on other sites More sharing options...
digger144 Posted February 19, 2012 Report Share Posted February 19, 2012 definitely trapped air in system remove caliper hold it above master cylinder &pump fluid uphill, it works every time you can pump allday down hill &never shift trapped air, good luck Quote Link to comment Share on other sites More sharing options...
cabby Posted February 19, 2012 Report Share Posted February 19, 2012 definitely trapped air in system remove caliper hold it above master cylinder &pump fluid uphill, it works every time you can pump allday down hill &never shift trapped air, good luck That's what folk said to me when I had the very same issue with bleeding a beta, turned out if was a dodgy caliper. Quote Link to comment Share on other sites More sharing options...
rev3 Posted February 19, 2012 Report Share Posted February 19, 2012 When you fitted the new seal kit did you make sure you filled the caliper with brake fluid?. what I mean by that is when you were pressing the pistons into the housing was there fluid in that side of the caliper. If not then it will be an absolute pig to bleed. Quote Link to comment Share on other sites More sharing options...
inchhigh Posted February 19, 2012 Report Share Posted February 19, 2012 make sure when you are bleeding you pump the lever 4 or 5 times before you hold lever and release the fluid and just a little bit at a time Quote Link to comment Share on other sites More sharing options...
0007 Posted February 19, 2012 Report Share Posted February 19, 2012 Firstly and most importantly never let air into the system unles you rebuild the caliper or master, if you change fluid just bleed down the fluid level in the master and then sop the rest up with a tissue, then add clean fluid and bleed it through If you have air in the caliper take the caliper off and Push the piston all the way back in This pushes everything back to the master Keep the piston in with a clamp and bleed as best you can Then pump the caliper full, pushing the piston out (make sure it does not fall out) Then push the piston back in, hopefully this pushes the air back out through the master, it will want to overflow Try this a few times, once you have a little pressure, bleed the banjo bolts Just never let the master suck air, I did that with my rear brake and it was a PITA Good luck Quote Link to comment Share on other sites More sharing options...
nzralphy Posted February 20, 2012 Report Share Posted February 20, 2012 Never had a problem. Never had to bleed up hill. Never had to remove a caliper. Never had to bla bla bla. Every one thinks Betas are "special". Balls. Beta's aren't special..... it is the same system fitted to most other motor cycles! Stop the BS and learn good technique. Does it need new seals? Fit them if needed. Make sure the master cylinder has clearance between it and the push rod/leaver. Remove the cap. Then pump-hold-bleed-close-release fast. Actually quite fast. Works every time. Every time. Quote Link to comment Share on other sites More sharing options...
crashmonkey Posted February 20, 2012 Author Report Share Posted February 20, 2012 Thanks for the comments guys, I have a fair amount of mechanical experiance but this has got me stumped .. but I will win in the end The only thing I havn't tried are replacing the caliper piston seals, but they are not leaking. I try doing the piston assembly submerged in fluid as i'm running out of options! I'll let you know how I go on. Does anyone know if you can just buy the caliper seals from lampkins or do you have to buy the pistons as well? Thanks All Quote Link to comment Share on other sites More sharing options...
graeme17 Posted February 20, 2012 Report Share Posted February 20, 2012 Thanks for the comments guys, I have a fair amount of mechanical experiance but this has got me stumped .. but I will win in the end The only thing I havn't tried are replacing the caliper piston seals, but they are not leaking. I try doing the piston assembly submerged in fluid as i'm running out of options! I'll let you know how I go on. Does anyone know if you can just buy the caliper seals from lampkins or do you have to buy the pistons as well? Thanks All Just had the same issues mate, replaced master cylinder seal kit and couldn't get the brake bled, tried upside down, forwards, backwards you name it. Eventually borrowed a vacum bleed kit and it still wouldn't bleed. It would appear that the new master cylinder seal has got damaged during fitting despite taking every care. Another m/c seal kit ordered, fingers crossed for this time. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 20, 2012 Report Share Posted February 20, 2012 Have a good look at the hose, where it runs, where it has up loops in it, and is the bleed nipple at the highest point of the caliper. My mate had this problem on his gas gas and taking it off the bike and hanging it up overnight cured it, this allowed all the air to get back to the master cyinder. Check the lever adjustment has not been tightened in too far or the fill hole in base of master cylinder may not be uncovering properly. Another problem could be corrosion (like a white powder) behind the slave cylinder seals, this makes the pistons retract more from the disc than they should. You usually have to split the caliper to get the seal grooves clean, first use a piece of hooked wire then polish out with wire wool pressed into groove with screwdriver tip or similar. Cheers Quote Link to comment Share on other sites More sharing options...
crashmonkey Posted February 20, 2012 Author Report Share Posted February 20, 2012 Just had the same issues mate, replaced master cylinder seal kit and couldn't get the brake bled, tried upside down, forwards, backwards you name it. Eventually borrowed a vacum bleed kit and it still wouldn't bleed. It would appear that the new master cylinder seal has got damaged during fitting despite taking every care. Another m/c seal kit ordered, fingers crossed for this time. How do you know its the M/C lip seal? can you see that its damaged? Just wondering if this may be my issue. Quote Link to comment Share on other sites More sharing options...
al_orange Posted February 20, 2012 Report Share Posted February 20, 2012 I've only ever bled mine once - that was after fitting new seals and pistons to the caliper. I back bled them using a syring (no pressure) Then forward bled with the OLD pads in (tiny bit of pressure) Then took the whole lot off and hung it up for a day or two, then normal bleed with new pads (almost good pressure) Cable tied the brake lever back over night and gave it all a good tap with a screwdriver (perfect!) Quote Link to comment Share on other sites More sharing options...
pindie Posted February 20, 2012 Report Share Posted February 20, 2012 Once you have pressure I'm all for the tie lever on and leave overnight approach. It really works. Quote Link to comment Share on other sites More sharing options...
0007 Posted February 21, 2012 Report Share Posted February 21, 2012 can you tell us where this started? Were you just changing the fluid? Ochams razor means the simplest most obvious answer is usually the correct one This means If you were changing fluid and now you cannot get pressure, you don't need to rebuild anything All you do is make more questions Quote Link to comment Share on other sites More sharing options...
crashmonkey Posted February 21, 2012 Author Report Share Posted February 21, 2012 Oh yeah baby Sorted, must have had trapped wind, sorry air behind one of the caliper pistons, I decided to pop the pistons out of the caliper and assemble submerged in fluid.I thought when I'd read this in another thread that I would ~never~ go to such outrageous lengths ... how desperation can drive you The design certainly lends itself to air getting trapped with no means of escape. Rest bled up a piece of cake, brakes now rock solid Thanks everyone, nice this site is here to help folks out, have one on me Quote Link to comment Share on other sites More sharing options...
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