Or real, your suggesting brush on paint application! It is no where near April first. How picky are you Bro? Is masked off painting gonna be "good enough" for you? Personally, I would be taking it apart if possible. Owning two 1985s, I know what a motor can look after some years. My 1990 looks like it was sprayed with thinned out watercolors from the factory. If you ride enough, everybody gets the front lower sections of their motor paint sandblasted off all the way up to the water pump elbow. Can I have an amen!
If you don't sand these areas, it looks like sh!t when sprayed over. I have used Rustoleum's Industrial Enamel rattle cans. It goes on thick enough in two coats and retains it's gloss. There is a matching clear for it but it makes it look thick and unlike the original. How Yamaha ever sprayed these motors so thin yet had good coverage is beyond me. I have seen some motors that look like the painter missed and got poor coverage in those deeply reccessed areas. Do you have and spare parts you can practice on? By the way, flat black has got to be the easiest most forgiving color to apply. Do decent prep with prep solv or thinner/ reducer and you can't miss!