Modern Vespa

Random thought. I understand that older models had metal shrouds. The p-series on (or maybe earlier) use plastic ones, surely for cost reasons.

What I am wondering--would a metal shroud cool better? I am imagining a metal shroud with fins on the outside to increase surface area, but even without those; the hot air in the shroud would radiate out to the metal shroud and dissipate; the shroud would also presumably touch the cylinder in places, leading to more heat transfer.

Anyone up to making a metal p shroud and testing my theory?

Metal cover
https://www.scooter-center.com/en/cylinder-cowling-oem-quality-vespa-px80-px125-px150-sprint150-vlb1t-gt125-vnl2t-gtr125-vnl2t-metall-stamped-7900122

Yes, your instincts are correct. Plastic is an insulator and metal a much better conductor and will help dissipate heat better, especially if painted flat black. Science.

But I think the fins might be overkill. Still it would be interesting to see what you come up with though if you do go for it.

Aren't these effectively just duct work to direct the air from the flywheel over the cylinder fins? I would imagine that they do very little of the cooling themselves, but again it's just a guess. It would be interesting to see what the actual difference would be between the two.

I would agree and expect to see little difference, but cooling is cumulative and it all helps if you might be on the edge sometimes. It would be interesting to see if the difference is noticeable. Any volunteers who've compared both on the same motor, who want to say what they think?

Dammit, one more scooter-related thing I will have to buy. And maybe j-b weld for some fins.

Get the stainless version of the flywheel and cylinder shroud.