The side cover in the attached photo has been painted several times. What you are looking at is Black rattle can on top of Gold on top of the original Red Candy on top of the original Silver Basecoat.
To get the rattle can off, I softened with a swift application of stripper (apply with paper towel then quickly rinse off) then scraped with very sharp 1/2" wide wood chisel (scrape at almost 90o to the surface).
The Black layer paint comes off in very thin curls. The Gold underneath comes off in even thinner curls that crumble easily - almost a powder. In places where the lower Gold paint layer was not sanded properly, the paint comes off in chips as the chisel is scraped along, exposing the bright red original coat - especially in the tight corners.
Once the Gold coat is thin enough so that I can see the red underneath, I'll use a 120 grit paper - you can see what that looks like on the aircleaner side of the cover, as the silver basecoat is exposed.
Even with the scraping technique, the inside corners are still difficult to sand properly.
I estimate 3 hours of scraping followed by 3 hours of sanding prior to applying the first undercoat.