i have major smoke blowing out the exhaust and even dripping oil to out, tore the motor down and did not see anything wrong, i took it to head and jug to the shop they installed new valve seals and they did not see anything either, my jug is bored to the max, is the only other thing that can do this is the rings? iput it back together and i think it smokes more know, i have been running this motor for only 2 months what do you think happened i change the oil after each race, or weekend ride, any input please i miss it already and it has been a week!

 

Rings. If it's "Bored to the max" get a 440 kit.

 

A racin buddy of mine had the same thing happen to a 2000 400EX this spring, He put a piston and rings in it and it dont smoke a bit now.