You wont get a good finish with cans, powdercoating will give a better finish. The best finish will be 2 pack paints as used by bodyshops. If you ever want to paint one yourself with car paints, strip the parts to bare metal. If the frame is in good order use a scotch pad to roughen the surface.Then there is no need to put on a 2 pack primer a thin coat of etch primer will do then add your colour. One good thing is if you have any dents fill them and 2 pack prime over the filler, rub this down with 500 grit if your painting a solid colour, or 800 if your using a base coat colour.
Solid colour is paint only, you apply the paint, 3 coats and thats it your parts are done and are shiney !!!!!!
Base coat was mainly used for mettalics, where you applied the colour which had the mettalic in aswell, and then you applied a laquer to give you the hard shiney finish, base coat is used on all cars now i think as its now water based and not solvent.
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So to round it off
you wont get a good shine off cans, polish and solvents will eat into it and can take the paint off over time.
powder coating is tough, although a bit thick and doesnt shine that well
2pack paints used on cars not as tough as powder, can be polished and shines well, also once fully hardened polishes great
base coat paint, for your mettalics, pearls, and candy colours gets covered with a 2pck laquer.
if you have the tools to use car paint, it works out cheaper than cans !!!!! If you want the bike to look well, but you dont have the tools, find a car painter who would do it on the cheap(guvvie job)
hope this helps, you need anymore info just ask mate/ ive been restoring a 1986 Escort Rs Turbo and have used 2 pack paint on the car and had the suspension powdered click the link below and you will see the difference between powder and 2pack
http://bbs.rsownersclub.co.uk/showthread.php't=77388