06 YZ 450, i replaced stock the stock piston/rings 2 years ago with a CP 13:1 piston and CP rings, also replaced cylinder with new one at same time. Never done any head work; valves were all in spec at that time. Since then, I have only put 30 hrs on the bike. Bike was running great this spring when I put it away for the summer. Got back home a couple months ago and pulled the bike out, went for one ride and it ran great. Then took it out again a few weeks ago and noticed it just wasn't running right; a lot of decel popping. I figured it was just running lean from cooler air temps an tried to adjust with fuel screw, but it never got it completely remedied. Took it out again a week later and problem was getting worse; noticed a little white smoke out of breather tube. Also noticed a big crack in the head pipe and figured that was the cause of my problems. Replaced the head pipe and took it out again yesterday, started up on first kick but once it got up to temp it started blowing white smoke out breather tube and then died. Played with fuel screw but couldn't get it any better. So I am assuming I have some valve problems or ring issues. Oil looks just fine, full level and doesn't look like any indications of water in the oil. Any ideas? Also, I don't think I want to take the time to do any more work myself. Any recommendations for repair work in the Vegas area?
Edited by atropine, November 27, 2010 - 10:49 AM.