TE511 rear master cylinder problems? Parts?

So I bled my brakes in the beginning of the summer, cause there was very weak pressure. then like 3 weeks later same problem, but I noticed that the rear valve wasn't ever closed that well. So I did an overnight bleed and the system seemed to work well for a while. Now I have very little pressure again, which sucks, cause I am finally getting better at wheelies haha. So I am thinking it might be the master cylinder. Is there a way I can make sure without wasting my time and money on the part? also would this be the correct part http://www.halls-cycles.com/default.asp?page=xstore&keyword=8000 A9447&submit1=Search ? seems like a lot for a small part to me.

Hi there,

I had the same problem on my TE450 a few weeks ago, i went over EVERYTHING, cheked for leaks on the hose`s, checked the O-rings, container for brakefluid and cheked all the crews/nuts ect and could not find anything wrong.
When i took of the rear caliper i saw the piston was wet, so i took the caliper apart and changed the rings and gasket and it works perfect.

Hope this helps, good luck!

Another commonly overlooked thing is the free-play adjustment of the brake pedal.
There should be a small amount of movement of the cylinder rod from the pedal before it contacts the cylinder piston.
This allows the piston to travel all the way out to its stop & let it draw in fresh fluid from the reservoir for the next stroke.
If it can't, the pedal can be ok to begin with, then get progressively worse as you ride.

I have adjusted quite a few out on the trails for mates of mine...

Ok great, thanks. I didn't really think it could be the mc cause I haven't ridden that hard on the rear brake. Looks like I have some new things to check. Can you tell me which ktms use the same master cylinder

Most of the ones I've seen run the same Brembo brand cylinders as the Husky. Just a matter of what bore size they/you have.

So I did have the brake adjusted poorly. I fixed that and bled the line, but I still can't tell if I am getting the full pressure that I should. I know it is hard to judge this without feeling it, but how much bite should I have. When I am stationary and I put the brake to the floor the bike won't move, but I can move the bike under my own power when the brake is halfway depressed. I can't lockout the backtire while moving at slow speeds on pavement either. IDK if this is normal or not or maybe there is another adjustment I can make

It should lock the rear tyre easily at low speed.
There's possibly still air in the system.
Another way to bleed it is to use a large syringe filled with brake fluid.
Attach a price of hose to the end that fits the bled nipple. Get the air out of the hose, fit to the bleeder & crack it open, slowly force the fluid back through to the master cylinder. If that's no good, likely to be a bad cylinder.

Replace your brake fluid with DOT 5.1. All brake parts are interchangeable with KTM.

If you use it, make sure it is 5.1, not 5 though.

+1

Parts can also be bought HERE

Thanks guys, I have been seriously busy so I am not able to do much work or check this thread too often, but you guys have been really helpfull

Bump to bring this thread back up. I have a newish 2013 TE 511 with 700 km's with the same problem..bleed the rear brakes and two weeks later no rear brakes again. Obviously a defect in this bike. Was a common fix ever found?

Not a common fault.
Almost never hear of brake issues on our FB page.
First check is to make sure you have correct pedal free play in the pushrod into the master cylinder.
From there, if you still have issues, inspect for any system leaks or corrosion and try Reverse Bleeding with a hose and syringe from the bleed nipple to the master cylinder.