UPDATE: Went riding this past weekend for the first time since the dealer replaced my rear master cylinder under warranty. The quad had 10 hours on it when the master cylinder was replaced. Felt great sitting at home in the garage. Within the first hour of riding I noticed the rear brake doing the same thing as before, that is, it goes to the floor again. As I type this with one finger my other hand holds the phone trying to get ahold of Polaris, (fifteen minute plus wait time). To be continued...

 

Cutty I feel like I havent got it bleed right....Im gonna give it another shot and see what gives...I think Charlie is right...
I"ll let ya know after I get time to mess with it.....thanksBud for keepinmg me up to date..by the way have you ever added any oil to your 800?Ive got 2 of them and ive added a little to both between changes..no leaks no smoke perfect performance..

 

I don't think mine is a bleeding problem, when I got it back from the dealer it was perfect with the new master cylinder. I went out and bled the crap out of it today still the same and it won't pump up either. Anyway I talked to the mechanic today and he says he is going to order another master for me. Finally did get through to Polaris today after a 26 minute hold time and they were no help, they said there were no service bullitins on the matter. Told me to call my dealer! I only have 13 hours on my 800 so far and have only done the 10 hour oil change. No oil usage at this point. Have seen some posts, not sure if they were on this forum or over on ATVquadsquad about bad rings though. Or was that the post you were involved in already?

 

interesting problem, haven't noticed that on my '05 700 EFI, although I amost never use the rear brake, there isn't much need for it when you have a balanced front/rear brake system on the handlebar in one pull....

I did film riding down a old road this weekend off of a mountain, dropped over 300 feet in elevation, camera in one hand running video and holding only the right grip and throttle....did use the rear/foot brake then, worked find, not overly sensitive though, so probably could use some bleeding....since the rear brake also allows you to shift in to high gear, i don't think it is supposed to be too sensitive, but should lock up the brakes when you push hit down hard, if it doesn't, then there is something wrong...mine will lock up the rear end...

 

Mine works fine at first then it goes to the floor!