I have 115 hours on my 06 CRF250R, and have changed the piston and rings every 30 - 35 hours. I did my last piston and rings about 5 hours ago (engine time) and it is burning oil now. I change my oil every 2.5 to 3 hours and have never had to put additional oil in between changes. Now based on my hour meter I am having to add about 100cc every hour. The bike is also smoking a little now. I am thinking either I didn't do a good enough job on the hone last time, or my cylinder is worn out of spec, and the rings didn't seat so I am burning oil. The bike starts cold first or second kick everytime and the bike starts right up after it is warmed up no problem. So I am not having any hard starting problems. I check the valves every 10 hours and they have stayed in spec since the first shim at 10 hours. Every time I do the piston and rings, I squirt carb cleaner in the intake and exhaust ports to see if any fluid leaks out between the valves and head, and nothing leaks, so I think the valves are still sealing ok. (not sure if that is a good poor mans test or not) The bike also seems to be down on power compared to the previous times that I have done piston and rings on it. Could it be as simple as the rings didn't seal? If so, with a 115 hours should I just order a new cylinder, piston, rings and re-do it? Yea, I know it is a pain to diagnose a problem over the internet, but I figured I would throw this out there. Thanks. BTW.... I am a slow old VET rider, so I am not pinging my bike off the rev limiter like the kids do all of the time.