Painting a moped is no different than painting a motorcycle or automobile. Preparation of the moped body panels for paint is the key to a good paint job. For best results, this will entail removing your moped's body panels, using various grades of sandpaper to prepare the surface, and then spraying your new paint, followed by a clearcoat. With a wide variety of paint colours and effects available, you can truly customise your moped with a new colour scheme.
Determine if your moped body panels are metal or plastic. Most modern mopeds have plastic panels to reduce overall weight. Remove the body panels you wish to paint; they are typically fastened to the moped frame with bolts. Wash the body panels thoroughly with soap and water to remove any waxes or chemicals which may be present.
Lightly sand the plastic parts with a fine grit sandpaper (300 grit sandpaper will work well). The goal here is not so much to remove the old colour as it is to uniformly rough up the surface to allow your new paint to adhere. You want to eliminate any shine in your original paint, as your new paint will be unable to bond to a shiny surface. Use uniform strokes to avoid circular patterns. Tape off the parts of the panel you do not want painted with blue painters tape.
Use Krylon Fusion plastic paint or a similar product on your panels. Stand three feet away from the panel and, using broad strokes, spray several light coats onto the plastic panel. Krylon Fusion bonds to plastic. It is also available in textured and metallic shimmer formulas if you want a powder-coated look. You may wish to lay down newspaper or cardboard underneath the part to ease clean-up.
Spray a clearcoat over the painted panel once the paint has dried to the touch. Clearcoat will provide additional protection and increase the lustre of the paint. Allow your parts to cure for at least an hour in a shaded place, then reattach the parts to your moped.
Note that since moped plastic parts flex during operation, make sure that the paint you are using is either plastic-friendly, or has flex additive. Without flex additive, the paint will be unable to withstand flexing and will crack.
Be sure to spray in a well-ventilated area that is out of direct sunlight.