If it s already flaking off it shouldn't be too hard to clean. Most people jsut spray there bikes wiht any paint they find, most likely enamel. The paint on the nbikes are either powder coated or laquer base. The laquer holds up real well to grease and fuel. I recommend getting some mineral spirits and trying that. If that doesn't work then try some paint thinner. It shouldn't hurt the base coast since thats most likely tougher than what they put on there. There is an other option thats probablyt safer. get some 400 grit wet dry paper at a auto store. Get it down the the factory paint. Then from there move to 600, 800, 1000 and 1500, then get some polishing compound and polish it. Use all these with water, it give you as smoothers finish. The 1500 grit when used wet is close to a polish. Try it on a small section to see hw it works and how long it will take. It will be very time consuming.