The sound reminds me of some other bikes Ive had with clutch basket problems. Because it rattles with the speed of the engine. The sound comes before there are tranny gears turning. Its something on the input side of the clutch. And I don't hear it any more after the clutch is fully engaged. In fact, this bike has the best feeling clutch Iv ever had. Smooth engagement all the way.
Any way, I'm gonna ride it till it quits, or I quit. From what Im reading here, some bikes have had this symptom all their life. So I'm giving it no more thought.
Its kinda like me, A little too young to be sounding old. It sorta fits me.
Ride safe.