Let me start off and say my 400 brakes were working ok. My brother wanted to take the bike on vacation for my sister inlaw to use. The brakes were working ok, but I wanted to bleed them to she wouldn't have to work to hard to stop the bike. It wasn't locking up the tires. So I decided to bleed them. I started with the back then the front left then the front right. I was carefull and refilled the fluid cup. The rubber gasket in the cup was streached out a little. I got it back together and wow.. The bike stopped way faster and even locked the back wheels. My brother takes it on the vacation. No sooner they take it off the trailer and start to go down a very steep hill the brakes went out. OMG. Luckly no one go hurt. He took it, and tried to bleed the brakes. He went and bought a new gasket for the fluid cup. Still no luck. He brings it home. I finally get to look at it myself. The piston for the brake lever was stuck in the the master cylender. I pulled it out. I made sure I had enough fluid, and then tried to bleed the brakes again. Now I have a new problem. I can't seem to keep any pressure. I can't get past the back brake when I try to bleed them. I get a little pressure then it all goes away. I hear a swooshing noise coming from the master cylender. Do you think a seal in the master cylender went bad or am I doing something wrong.

This is how I bleed the brakes.

I take off the cover to the master cylender. I squeeze the brake and crack the bleeder on the rear brake. I hold the lever in. Tighten up the bleeder and releace the lever. Check the fluid level, and add if needed. I do this until I see no bubbles. Then move to the front right tire and do it all over again. Then the front left.

 

Just an update. For those who might stumble across this in a search. My problem was the master cylinder. The seals were bad. I got my rebuild kit in the mail today. Put it on and blead the brakes in less than 30 minutes, and I was off. Screeming through the woods again. It was great

 

I was having the same problem with my 04 Boss. It wasn't the master cylinder that was the problem though. The little bleeder valve on the back brake for the peddle appeared to be working ok but wasn't seating in the caliper properly. I eneded up taping the bleeder hole out and just putting a button head scew in it with a copper washer on it and have not had any problems what so ever with my brakes since. I have done this to my neighbors 03 Boss also as he had the same exact problem of having no brakes a day after bleeding them, time and time again. Its a cheap and easy fix.

 

where did you get the rebuild kit and how do I get the piston out of the cylinder?

 

The best person for these quads to talk with is Rick. RCR raceing . Rick Ritter is his full name. Youcan just google his name with polaris and his company should come up. VERY informative and helpful guy. Give him a ring.