I can give you a small advice.
Ride your bike for half an hour a little bit faster 60-70kmph is enough or maybe little more. Thing is ride for considerable time until engine gets pretty hot.
now when the engine is hot and while you are still to reach home...
Now stop and place your bike on centre stand and give enough throttle or may be full throttle for may be 3 seconds..
now you will find your answer with smoke..

The thing is many bikes will not smoke when they are cool enough and we will not observe with full throttle when bike is hot enough. We will just think that bike is already hot and wouldnot care about to check the smoke and put it in parking.

As per as i have heard valve guides when they have problem and are hot may leak thereby giving smoke.
also we can't blame just the head with valves, oil seals and guides. As you know Piston, rings bore also plays a role in smoking.