Hi, I also have a problem with the gs500, when it stays still or on the go, between 8000 and 10000 rpm it makes a strange sound that you will hear in the video, I thought it was from a washer on the frame which at the vibrations makes that sound ... What do you think the sound is from?
VIDEO: https://www.youtube.com/watch?v=UHsnSfLy7FQ&feature=youtu.be
got the same noise at around 4500/6000 rpm, i don't know what is the cause tho.
Exhaust leak ??? If its rpm related its likely air related, not carburetion cos that depends on throttle position. You're not missing a cyl, so its not spark/electrical.
So air flow or vibration/resonance.
Cool.
Buddha.