I painted my motorcycles guard with a can of 120 rs spray in matte black.
Sanded with 320-500-1000-2000
First i sanded with 320 to remove rust bits, to scuff it and to remove any anti rust coating.
I filled in holes with some enamel that i had lying around and I didn't wanna spend much money buying putty or body filler, and the project was just for fun and aesthetic.
First i got a thick layer of enamel on the guard, let it dry in the sun and sanded most of it down with 320 untill the enamel was filling in the small dents and dings. Then 500-1000-2000.
After that, i washed the guard and cleaned it with thinner ( was lying around) and washed it again. Let it dry in the sun and i did 3 coats of matte black with 15 minutes interval each . I let it sit in the sun for a day. It did get some dust particles, sanded it down with 1000 and 2000, washed and dryed it and added a thin coat of matte black.
I let it sit outdoors for 36 hours, on the roof where it could get direct sunlight. The guard is metal and with matte black paint it got hot very quick allowing it to sort of "bake".
After 7-8 months the paint hadn't chipped or peeled. The color didn't fade at all. I'm the type of person that uses meguair's wax on a 2005 cd70, and the wax didn't harm the paint in any way.
Unfortunately I met a low speed motorcycle crash becuase i lost traction in rain and the guard fulfilled it's duty and took the impact, but surprisingly, the paint handled itself pretty well and didn't chip, just scuffed.
I had to replace it with a new guard that i don't have the time to paint now.