My bike is still giving me rear brake issues. I replaced the master cylinder and the bike ran good after I bled the crap out of it. I ran the motard wheels and everything worked sweet. I changed the wheels and lost back brakes again, completely. I replaced my rear line with a fren tubo line and I though my line could be broken, but in fact its still good, all be it a little bent and twisted. I pulled the piston out of the caliper yesterday and polished it up a little and when I put it back I noted the 1st seal is a little torn. I hoped for the best and popped everything back. I bled it again and it gets pressure fine, but after it sits for a while, the pressure just fades. Am i right in assuming its loosing pressure at the back? I read that these 450's can be a little beeyatch to bleed properly too. Any other place I should look?