I own a powdercoat business and have done many cases (honda, harley, ect.) with no ill effect to the parts. Its true you do have to pre-bake the parts to do somethng called outgassing. This opens the pores in the aluminum and lets the trapped air in the metal escape. I have used gloss, wrinkles and flats with ho problems. I've done just about any part on a bike including the cylinders.