Hey Guys, Its been a couple weeks with this 'new to me' beast. Great bike! But with all bikes some quirks to work out. On a few dirt roads / gravel roads the rear tire has locked up! :huh Don't notice it much on any light trails - maybe that's just cause I am not using it much.... ? And pavement of course it doesn't seem to lock up - but overheats for sure. I was told there was a warped rotor in the bikes recent past - perhaps this is the cause. I did some searching and came up with a few threads and this info for instance: http://www.ktm950.info/how/Orange Garage/Brakes/rear/pyndon_rear.html I understand there was a previous TSB that dealt with a 'fading rear brake'? this is the opposite. Also to note it locks up by barely touching the pedal. My plan was to get this kit go through the steps and essentially rebuild the system and bleed it and see how it goes?? any other suggestions?? cheers.
Fading is generally caused by the same symptoms you are having. Because the brake is dragging, the fluid heats up and eventually the brakes fade. In your case the first thing I would look at is the linkage of the brake pedal and see if it is binding and holding pressure on the slave, pull it apart, clean and re-grease. Next I would look at the caliper and make sure it is functioning correctly, pads are not binding on the pins, sliding free etc. If those two things check out then Id do a full rebuild, but check the easy and cheap stuff first
Sorry - should have mentioned the brake pedal itself does not appear to be dragging at all. I have cleaned it as well and greased it up and it seems free to move at will when I have the bike parked...
Well that takes some of the possibilities away. Try pulling the rear tire and see if the caliper looks like it is functioning correctly and see if the brake pads have even wear. It would be beneficial to put the bike on the stand and spin the wheel and see if you can recreate the problem as well. Did the PO say the rear rotor was still warped? When you spin the rear wheel is there a high side on the rotor that drags considerably on the brake pads? Do you see any major movement of the caliper on the pins as the wheel spins? Hopefully you can pin point the problem
Make sure you have the right brake fluid. The wrong fluid can expand when hot causing the brakes to lock up. I'd flush the system with brand new fresh DOT 5.1
What you are checking on the brake pedal is slack at the linkage/pushrod going up into the master cylinder. There has to be a gap to allow the piston to fully retract. Lots of threads on this check and the problem in general. If gap is not the problem, I'd be pulling the wheel and doing some inspection and cleaning on the caliper. The slide pins and pistons can get grunged up. For my money, go ahead and put seals in the caliper, fresh fluid and bleed. Good luck
The recall I am familiar with was for my '06 SM. It involved changing the master cylinder diaphragm. I never noticed any problem before or after. FWIW
The recall was due to sudden mushy brakes. 98% of the time the master cylinder lid is not venting correctly. Look closely at the gasket and make sure it has not sealed off the two small slots that let air in behind the diaphram. You can trim the herniated bumps with a new very sharp razor.
