Rear brake kaput

03YZ450F

I'm assuming it's probably the master cylinder. Just want to try and make sure before I buy a rebuild kit.

It worked fine last time I used it. I tried to close the caliper after replacing the wheel and nothing. Fluid lvl is good, I tried bleeding it and it just oozes out. The piston barely moves when I pump the brake lever sometimes even moving back in. When it finally closes up on the rotor there is no presure. When I open the bleed valve on the caliper and push the piston back fluid squirts out like it should.

Not sure how to test which one is bad but a master cylinder kit is far cheaper then a caliper.

Sound like the master cylinder is just worn out?

I'm having a similar problem only where the piston isn't coming even close to the rotor. :ride:

Well I went ahead and ordered the parts for the master cylinder. I pulled it apart cleaned it out tried to bleed it again and still nothing (wont even make pressure when I plug it with my finger). We'll see if the new parts fix it or not. I'm thinking if it was the caliper the seals would be leaking fluid .... could be wrong though :ride:

Guess if this doesn't work I'll replace the seals in the caliper.

I know that mine wasn't the master cylinder, because neither the 450 one that I have nor the 400 one worked with the same caliper (my bike is converted)

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