I had Keihin 34's on my bike with a 40 over bore, super stock pistons, mild port on cylinder none to the cases & it was on alky & ran perfect it ran 3.9s & 3.8s in 200 feet & ran 1 3.7 but the guy that I race with had on on 34s & ran 3.5 & 3.6 on alky on 60 over bore stock cylinder. but thats full drag bike with drag pipes