Crankshaft

Disclaimer: Vespa Labs contains information that is VERY likely to wreck your scooter and possibly yourself, both intentionally (i.e. gaining more performance while sacrificing reliability + safety) and unintentionally (i.e. misleading or incorrect information). Vespa Labs originated as a public wiki and is only a collection of random notes and intended as a dumping ground for information and not as a properly reviewed source. The same disclaimers that wikipedia.org use apply to Vespa Labs. Also be aware that Vespa Labs is an international site and therefore may contain information that is not road legal in some countries/states and may also invalidate insurance policies. Treat all information as experimental and for "race use only" (i.e. not for road use - even if it is implied or explicitly stated). Refer to and adhere to your local road and legal rules, as well as the manufacturers recommendations
The short version: using this information is at your own risk