Cleaning the stains on my Full Throttle

Looks like it's in your seat too. I would try polishing compound on the tank and acetone one the seat

Someone has sprayed something that’s marked the tank and seat. The paint on the tank is also severely scratched from improper cleaning methods. Is the finish a matte finish or gloss? If gloss, it most likely is clear coated. Someone good at automotive paint correction could probably polish out many of the scratches. That may remove the splotches too. If it’s matte finish I don’t know if it’s as easy to polish out.

Suggest you find a good detailing company near you and let them look at it.

I had some nasty stains on my Hypermotard some years ago as a result of an old fire main that leaked rusty water over the tank headlight and nose. Nothing I did made any difference. Took it to a local detailer and in 10 minutes it a good as new.

May not help, but I would give that a try before I try anything else and damage it.

WD40 ?