I've mentioned previously about Yamaha's "RingFree" which is a fuel system cleaner and top end cleaner.
It is NOT a fuel stabilizer.
It's very popular in the marine world. I use it in all my gas powered machines. IMO, an excellent product:
I was told incorrectly the wrong mix for a shock...
I was talking to a guy here at work that does up old bikes and he got this from some hot rodders apparently its an old farmers tip:
mix about a cup of Molassess with a gallon of hot water, fill the tank and leave for about 24 hours, the rust apparently just falls off leaving clean metal...