It may be a problem with the Turkey Valve. It is the engine breather system. Continue reading what ever you can find about this, both here and on the web. I can't tell you it is the Turkey Valve, would be nice if it was is all I know.
Are you using 20w-50 oil? We won't go into what oil or what additives, API rating, or anything else. If you are running 10w-40 because it is Winter then I suggest you start running 20w-50. This may cut down on the smoke while you are taking care of the problem.
How many miles on this bike? How many miles since new rings, rebuilt heads, or any major engine work?
You will need $100 for gaskets and parts to remove the heads, $500 for rebuilding cylinder heads and more money for piston/rings work but can't say what you need till it is apart and measured.