here what i did for my bars and will continue to do its easy and cheap
first sand your bars down all around every area of the surface.Then, i dont even use primer so yea but you paint still last awhile,but anyway spray very thin coats of spray paint, do 3 coats of the color and you should be fine. Next, clear coat, this is very important. Spray evenly over the whole surface of the bars with atleast 5 coats is what i do seeing as tho more coats wont hurt and doesnt take long to dry eigther.
also make sure after each coat of paint you wait an hour or more till the coat drys. same goes for clear coat.
any other questions PM me