Hello,
I've just bought an overbored 450cc CB400F engine and was going to have a set of carbs bored out to 22m and rejet. however, the carbs, which are standard as far as I know, have a 22mm bore at the engine end but are choked to a smaller vertical oval cross section at the slides. Is this normal for the CB400 and is it possible to increase the bore size on these carbs (I don't have an oval drill!)?
Cheers, Mike J