Vespa / Stella cooling shroud spark plug gasket

thingiverse

This is an insert gasket to plug the gap on your Vespa's or Stella's plastic (i don't know if it'll work with the vintage metal ones) cooling shroud, around the spark plug boot. Works with a NGK spark plug boot. The point is to keep air from leaking out around your spark plug boot in order to force as much air as possible down around the cooling fins of the jug and head. According to my CHT gauge, just by plugging this hole, I was able to drop the peak temp at WOT in 4th gear by a few degrees. This may not be a lot to most, but if you're running a tuned engine, every degree cooler you can get, you take. (Consider running this in tandem with a scoop - plus it was an excuse to share a pic of my scoot). The hole on your shroud my vary, as may the boot, so I've included the Solidworks file for you to make adjustments. Enjoy.