To achieve 60 mph, you won't do it on a department store bike with a cheap China rice burner engine, at least not and live to tell about it. If you want to see 60 mph and live, you will need an engine that makes power easily without modification and a very solid frame. I recommend thick steel or chromoly. Nothing from a department store. Check yard sales/craigslist for American bikes. You MIGHT hit 60 with a 2 stroke kit, but the engine might not survive the necessary modifications for very long. Some engines that easily make enough power to go 60 are morini/ktm/ktmc and a 212cc predator. You will also want to add hydro disc brakes. It doesn't have to go, but it does have to stop. A walmart coaster brake won't stop you at 60.