Why am I smoking?

[atb7346]

I have a 416ex. When I start it from a cold start, it smokes quite a bit until it warms up. When I am riding at normal temp, if I throttle heavy and let out, it smokes while letting out of the throttle. Or if I am coasting down a hill and I down shift, it smokes a lot. It is almost like the oil is getting drawn in threw the valves. I replaced the valve stem seals when I rebuilt the top-end last year. It has done this since I rebuilt. I fear I won't be able to sell with this bit of smoke.
HELP!