Do you use single stage urethane on the fender and tank like you did with the frame? Can you give me a quick summary of the process you use ... number of coats, sanding between coats, coats of clear... What kind of paint do you like to use?
Never try and use single stage on tanks and seats. You can do it but once again you're working harder for an inferior result. When you f&?! it up; and you will if your a beginner, you have to wait 12 hours and repaint the entire thing.
I only use single stage on frames. It cuts out orange peal but most importantly have you ever tried to buff a frame? Me neither and I don't wanna try. I use restoration shop because they have more than 100 colors to choose from and for the $ it can't be beat. Don't listen to the paint snobs; sure there are better paints but they cost a lot more.
Nothing really special about the paint prep. I use kustom shop 2k high build primer. Do not use the duplicolor crap; etching or others, urethane will not adhere to it. The clear I use is also from kustom shop.