I have an 03 crf 450 that i have owned and maintained since it was new. I just finished my second top end overhaul on the bike. This time I replaced all the valves and springs,as well as the piston and rings.My question is now when i start it i see a slight puff of smoke when it is revved when the engine is cold. when the engine warms to operating temp i see no puffs of smoke. The bike only has been ran in the garage for about 5 minutes but never ridden or put under a load. Is it that the rings are just not seated yet or did i do something wrong. I did not notice this with the last rebuild or before the rebuild.