Modern Vespa

So when you upgrade from a 150cc to the 190cc piston. Does that mean your variator is supposed to change to 190cc as well? Or do you still use a Polini Vespa s 150 speed variator? Or at least something the aquivalent of Polini's Maxi Highspeed.

Odd title?

Can run all stock transmission parts.

I modified the title of this post and turned one of the underscores into a space, as the long block of text was breaking the layout on the main page.

Still curious why the OP used underscores here. It just makes the title harder to read, in addition to breaking the HTML layout.

You can use just about any variator, but -- if you want optimal performance -- you will need to customize your variator weights. First, you need to decide whether you want to optimize for maximum acceleration or for top speed. If for top speed, you'll want to install an upgeared final drive. Then, you can tune the variator weights. A simple digital tachometer is useful for quantifying the effects of different choices.

It's not a totally straightforward process; it requires experimentation.

Still showing up as underscores here.

I only changed one underscore. That's all that was necessary to provide a spot for the text to wrap.