Here's how to do it right, but you MUST follow the directions... no shortcuts!
Painting a bike well takes a bit more than a whim, a 6 pack, and a weekend. Do it right and it will look great, do it wrong and you'll wish you never did it.
This answer is long but will give you an idea of what to do. Want a quick answer? Take the bike to an auto body shop and have them do it. It'll cost about $100 if YOU take the bike apart.
Use DUPLICOLOR brand LACQUER available at most auto parts stores. In the UK, I don't know if the brand exists so you'll need to locate a brand of acrylic lacquer. DO NOT BUY ENAMEL OR URETHANE!
You'll need 1 BIG can of grey sandable primer and 1 big can of flat black lacquer.
Here is a quick explanation of what to do...
1) After completely disassembling the bike have it sandblasted to remove ALL the finish. If the frame is aluminum, it should be walnut shell blasted, or you can chemically strip the paint. Just make sure all the paint is OFF the bike.
2) READ THE CAN INSTRUCTIONS, then spray it as soon as possible with grey SANDABLE lacquer primer. DUPLICOLOR brand paint is all lacquer, I think, and you can get it from your local autoparts store. Buy the BIG cans, not the small ones. Apply at least 1 full can, in coats, 15 minutes apart. Don't worry about light runs for now.
3) Wait at least 48 hours. There is a difference between dry paint and cured paint... it needs to be cured. Sand the primer using 220 grit aluminum oxide paper (white in color) or wet/dry paper (black in color) until the surface is smooth. It shouldn't take much unless you have a lot of runs.
4) Using a tack rag, lightly go over the entire frame (don't rub!) to remove the sanding dust.
5) Apply several coats of the color of your choice. Make sure the frame is completely covered, it is not necessary for the color to be on thick. Follow the directions on the can. Since you are going with flat black you should apply at least 5 coats. Apply coats 1/2 hour apart. Be sure you cover every part and do NOT get runs. If you get runs you are applying it too heavily.
5a) IF you wish to add decals, wait at least 8 hours, apply the decals, then continue.
6) Let the frame alone until you can't smell the paint anymore when you get up close and take a big whiff. If you can smell it, it ain't dry! This will take 2 to 3 days at least.
If you rush this you will end up with a sloppy mess and you'll kick yourself for ever trying. However, if you take your time and do it right it'll be a very cool feeling.
