If you’re wanting to paint the frame with spray cans, I can tell you I have had great success with Rustoleum Professional grade paints.
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I have painted a couple of old bike frames , just working around the motor in the frame and the results were really good.
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On my XS2, I had the frame powder coated, but all the bolt on pieces , such as the center stand, swing arm, battery box, and steering head were all sprayed with Rustoleum, and the results are virtually indistinguishable.
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The key is in the prep. Before you do anything , your frame needs to be clean clean clean. Get all the dirt and gunk off and then wipe everything down with a paint prep solvent, like this...
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Once everything is clean, now you can sand to scuff up the original paint, smooth out any chips or rust. If you fail to remove all traces of grease or oils before you sand ,you will just grind those impurities into your paint and your new paint will develop fisheyes. Then everything gets wiped down again with paint prep. I do this with clean white paper towels and I keep doing it until you can no longer see any dirt or oil show up on the paper towels. Dry everything off and now you can spray.
On my BMW and old Triumph that rattle can Rustoleum held up really well and kept its gloss after many years.
Good luck to you on your project, however you proceed.
-Bob