How do i paint my dirt bike plastics?

I have a 1990 kx 125 and i want to paint my plastics white. i cannot find any white plastics for it so i am forced to paint them. i want to use spray paint so if someone could tell me what type of paint i should use and how i should paint them that would be great!. or if someone can find my 1990 kx 125 plastics in white or black please tell me where to look. thanks!