KDXRIDER.NET

I bought a 2001 KDX 220 that had a rear brake that was previously stuck, and is now not operating correctly. It'll give a little pressure and barely try to stop the rear wheel. I took the rear brakes apart (pulled seals, pulled rear piston/puck, took apart master cylinder etc). It was very dirty. I gave it a good cleaning and proceeded to bleed the brakes and thought I would be fine.

Nope.

Still not holding or building up much pressure. When trying to bleed the brakes I can see the fluid go back into the reservoir when I'm trying to build up pressure by pumping the pedal.

The bore in the master cylinder looked good, but perhaps I missed something? Any similar experience or suggestions?

Thanks in advance.

P.S. Stupid question - The piston on the rear calipers DOES go in with the hollow side OUT, correct?

Welcome to the forums.

Yes, hollow side out

Did you replace the dust seal and fluid seal(s) or just put them back in?

How do the pins look? Any grooves worn in them?

I took the seals out, cleaned the areas where they sit, and put them back on.

The pins are worn, definitely need replacing. Will put an order in for them.

Also have a broken nipple on the brake bleeder screw (like that when I got it) and hoping I can find a replacement without having to spend $10.

It had quite a bit of crud in the brakes. In fact the bleeder screw hold on the side of the bleeder was filled with gunk and wasn't bleeding out the top anymore, was bleeding through the threads.

Now that I think about it, I might have quite a bit more adjustment to pick up on the pedal where it connects to the master cylinder. I'll adjust that out and if that doesn't work I guess I'll just buy a seal kit and some new pins as well.

Any other suggestions while I have it apart (again)?

I am not sure on pricing, but there used to be aftermarket pins.

I would inspect the master cylinder piston ... I had a similar problem on my 220 , water had made its way past the rubber dust seal & over time corroded the internals ..unfortunately I wasn't able to rebuild mine but after fitting a good secondhand unit it now works as it should ... A rear foot brake lever with excess up & down play & poor stopping power is sometimes a good indication of a sticky piston .

Well, I took it apart again and one of the seals on the master cylinder piston was on backwards... That was the way it was on it when I got it (without brakes working) so I put it back on that way. I now have the fat end of both of the seals facing towards the banjo bolt and I have stopping power. I might buy a rebuild kit anyway as the dust seal on the rear brake is a little wonky, but fits back in.

My brother has a similar model KDX as well and after feeling his brake pedal, mine feels similar. I cannot bottom it out anymore, but it doesn't come on suddenly like some of my other bikes.