The divine equation, proper proportioning of size of tank , tail , seat, fenders. Something relative to building customs , was almost done for me by Ryca, I only had control of alignment. I think Ryca did good on the tracker model , but I’ve seen several that did get alignment messed up. When my tank was black & tail white , the tail looked too big. Reviewed some old & newer pics. Most definitely prime all body parts the same color. I didn’t like the tail too big but after all painted the same it was perfect. Now when I look at tank & tail are near perfect in my eyes. Looking at other big singles I see something funny on mine , almost all proportions very good but the engine and my 2” exhaust look too big for the rest of the bike. I find it amusing.  If it’s out front people slow some stop some get out take pics. Whenever I stop somewhere it draws attention. I see a bike not quite finished but others see it as done , finished product. It makes my heart pound , it is sexy ! Maybe it is done !