Is there a way to identify whether an ally head has the larger valves without taking it off? My bitza has an ally head fitted but it also came with a spare. I'll measure the valves in the spare - what sizes am I looking for? Are there any distinguishing features on the head? Both have cast in single carb manifolds. I'm thinking 1 1/16 vs 1 1/8 intake/carb dia, is this correct? Thanks