Modern Vespa

Hello vintage fans, let me ask your advice -

I am slowly putting together a 1973 Vespa Rally project. The motor has been rebuilt with a Pinasco kit and a long stroke Mazzuchelli crankshaft. The bike has autolube. I have the original 24mm Dell'Orto carb, but I also bought a 26mm Spaco. Either of them should work with the autolube system.

I'm sure that with a big enough main jet the original 24mm carb would work okay, but given that the displacement will be around 225cc, should I perhaps try the bigger Spaco? Some say their quality is not as good...

I know, I should probably have kept it all stock, but what's done is done. I still have the original barrel and piston if I want to revert it to factory spec.

Any thoughts? And/or jetting suggestions?

Well, as far as jetting the 24mm, it depends on the exhaust. I would try about a 125 or so main jet.

The 26mm would give it a little more pep. The spacos are fine carbs. We use them all the time. You've built a motor that's designed to create lots of low end torque. Smaller carburetors help with low end torque. I'd try it out with 24mm first. But, that would also depend on what exhaust you are running. If you're running something fancy, you might try the 26mm.

Thanks, Motorsport. I've got a Sito Plus pipe ready and waiting.

The Sito + will be perfect for that. I would just try the 24.

Cheers, mate!