I have done this successfully two ways but you need to be careful using both. First I recommend doing any of this on a small test area somewhere on the bike that is inconspicuous. Now I have used Acetone on a rag and slowly rub in small circles till the rattle can job is removed. If the base coat is good baked on enamel then it will remain. Do this in a well ventilated area nowhere near fire or sparks. The other thing I have used successfully is a product from 3M that is a paint remover paste. I comes in platic bottles and literally looks like elmers glue. You spread it on and time it. The longer you leave it the more paint it removes. It will go down to the bare metal if you leave it a long time. It is not quick but it spreads on like a paste and I find it removed rattle can spray in 15 minutes or less and leaves the base coat in place. You can wash it off with plain water and you must wash it off or it keeps working. The great thing about this product is that is virtually has no odor and can be used indoors without any ventilation. It is water clean up so you do not have to worry about a big mess. It is also slow acting, unlike the Acetone. You can get it in most hardware stores, I found it in Sears and I'll bet Home Depot carries it. The plastic bottle is black if I remember correctly.
Ray Homiski
Elizabeth, NJ