Amal carb size choice

My 71 has a pair of 32 mm amals fitted. The carbs fit onto a pair of 30 -28mm manifolds that match the 28mm heads but don't match the carbs.

I'm thinking of replacing the worn carbs with a pair of new Premiers, the question is what size to use. It would seem to me to be logical to use 30mm premiers, which would match the manifolds and reflect the carbs that were fitted originally.

Comment please

Charles

IIRC various tuners have found that a mismatch on the inlet as you have can be an advantage for gas flow at certain rpm. I think jseng has done some testing on this.

I think the proper 30mm's will be ideal, offering great performance, best chance for a stable idle and no hassle tuning for your 750.

I've done this experiment to state the lip definitely helps the off idle to mid range grunt throttle snap response to at least the ton but then may hinder full flow top out speed a dozen or so mph above the ton. Still if ya know how it felt with the lip would be educational if any thing detectable by blending manifold. On the other hand the 30 mm carbs would likely be more snappy than bigger ones up to at least hi way speed flows 60-65 mph before falling behind the bigger carb.

Agree with pete v 100% on this one.