After many many many "adventures" with different kinds of carbs (Keihins, Mikuni HS 42 and 40) I proudly announce that I've finally found good carb to my 1987 Sportster. It's S&S E type Shorty (jets : pilot 0,295 - main 0,70) It works perfect. I don't know if it's economic (it matters to me - in Europe gas prices start from 5 $ per gallon) but I'll check it when weather gets better. Perfect combination between CV and Mikuni. Nice sound and powerful bike.