Modern Vespa

Don't quote me, but I think all small frame engine cases are the same after like late 60s, when they introduced the 125 top end to the small frame lines. To make the case compatible with all size top ends offered in the frame size. So any of those cylinder kits for small frame. I believe I read it in one of my vespa all model books recently cause I'm looking at a 71 v90 to compliment my 78 v100 and wanted to double check that same idea.

But maybe someone who definitely knows for sure will chime in.

Probably anything fits, if the cases have the bigger "spigot" diameter of the later ones. I can measure a set of V50 cases I have, that definitely accept a 130cc cylinder and let you know. 43mm stroke will work for up to 102+ kit, for a 130+ kit you'll definitely need a 51mm stroke crank. This is what I've done on our "Special" build...

Unificata came in the fall of 1965 with the debut of the VMA1 "Nuova" and the Super Sprints. Unificata means unified. They called it that because they transitioned the Vespa 50/50S/90 to the new base with the large engine door and thus unified production, all small frames now being built on the same platform. They had to do this because they had transitioned to a larger engine case for the 125 and they only wanted to manufacture one engine case moving forward just as they only wanted to manufacture one chassis moving forward. The larger engine case requires the unificata chassis. With the unificata molds, the pronounced curve at the forward end of the bottom of the cowl is gone. Because it is still short wheelbase the floor and the sides still reach the same distance back.

I'd suggest you get the longer crank. I ran a Polini 100+ kit of some kind on the stock 50Special crank and didn't like at all. No real power until you are winding the piss out of it, please gimme 125cc or more for some torque! Especially if you are running a stock 50 Special 3 speed.

I'd suggest you get the longer crank. I ran a Polini 100+ kit of some kind on the stock 50Special crank and didn't like at all. No real power until you are winding the piss out of it, please gimme 125cc or more for some torque! Especially if you are running a stock 50 Special 3 speed.