What I find kind of strange, the 2hp base model maxi takes a #64 and the Newport, Sport, and MKII 2hp maxis, which are all higher performance bikes than the base model maxi, all take #56 jets. You'd think the higher performance bikes would require more fuel.
I wonder what the difference is in the base model maxi, maybe the bigger jet is to restrict it by richening the mixture? Or maybe it's just built cheaper and less efficiently for some reason?