Hey everyone, fairly new here, anyway....
Sorry if this has been said but I couldn't find my specific problem, so I thought I'd post my solution just in case someone needs it one day.
My GS500F had a terrible buzzing noise at about 7-8.5k RPMs (been said before I know). From the front of my bike, I could see where the black plastic behind the windscreen had vibrated so much, so many times, that it had worn a white line into the windscreen itself. This was located just above the word "Suzuki".
My fix, as simple as it was, was to get a piece of rubber (I used a cut off from a bicycle tube), remove windscreen, place rubber in the rubbing area, and reassemble.
All sounds simple but just wanna make sure it's said for future reference.
Feels like a new bike... I got to the point where I hated going past 6.5k just because of the sound.