Hey guys, I got a pretty weird one here. About 6 hours of riding time ago I did a top end on my YZ. Everything was in spec, and looked good. It seemed like my bike didn't get abused too much in its 5 years before me. I broke it in Dry and Hard (). Just a light coating of oil on the rings, and none on the cylinder. Hard acceleration and alot of decel. FWIW, the crosshatching was excellent on my cylinder, and I opted not to hone. My valves are a tiny bit tight, and I still have yet to install the shims (have them and will go in before the next ride). Its nothing critical, but I wanna get 'em back in spec. Now, when I start it up, if I blip the throttle (not anywhere close to redlining) within the first minute or two, I get a decent puff of white/blue smoke. After its warmed, it will not smoke at all. It did it just now. I took off work today, and since my bike hasn't been started in 2 weeks, I figured id start it up and take a few laps around the yard. To me, it seems like the piston rings did not seat right. I was careful about the orientation of all the rings, but like I said, I didnt hone because the crosshatches looked new. I feel like once the rings warm up good, the seal and dont allow oil past. My buddy (a mechanic) swears its the valve guide seals. I think the fact that it only does it around startup is steering him that way. What gets me is that if I just let it idle, it will not smoke. Also, I had an old F150 with worn VGS's, and under decel it would smoke a little too. I dont get that on my YZ. Soo....anyone know what might be causing this? If its nothing major, I'd still like to fix it anyway. I think I might have asked this question before, but I dont remember, and I am sorry if I did. If it helps, I can take a video, so you guys can see. Thanks for the help.