Modern Vespa

Chandlerman has been huge help in QC-ing the jetting on my '64 Allstate. Thanks again!!!

My '66 small frame on the other hand is more of a Frankenscooter: a '76 VMA2M under the hood, with a P125 jug, Polini cylinder head and stock exhaust. The carb is a Dellorto 19/19 with stock 74/45/60 jets. I am looking for an opinion on the sufficiency of the stack considering the add ons. Thanks hive.

you mean a primavera 125 or did you somehow make a large frame cylinder work on a small frame motor??

It's a primavera PK125 cylinder

Jetting is spot on stock for a Primavera. I doubt there's anything really different between the PK cylinder and a Primavera.

I'm just guessing on the Polini head, but maybe it's reprofiled for better squish/compression ratio? If so, maybe go up 2 points?

Throw a CHT on it and run it hard as is. That'll tell you if you're getting up to catastrophic temps with the 74 or if you need to adjust.

I think the stock main jet size for a PK125 is 76.

I got an xl75 barrel and stock is 76 on a 20mm carb. Just check it's not a pk 125xl barrel , big ports on them.

Thanks all.