Hi Luca,
While a number of us were riding together last year on a hot day, smoking was noticed on a couple of our bikes. Do you still have your crankcase fumes going into the air cleaner? That is how I prefer to have them but, it also guarantees that the crankcase mist will be drawn through the engine and burned.
My guess is that when it's hot and you're cruising steadily down the road, the crankcase ends up with a lot of what looks like smoke but, smells like hot, agitated oil. Then if this oil mist gets sucked into the engine, it would almost guarantee that you'd get a cloud.
Does your bike do it all the time or only when pulling away from a stop, when the engine is hot? The amount of smoke you're getting might be normal.
