Most Vespas have had two-stroke motors, requiring a mixture of oil with the gasoline in order to lubricate the crankshaft bearings. The generous mixture of oil in the fuel produced high amounts of smoke. This drawback to the two-stroke motor caused any two-stroke motor over 50 ccs to be outlawed in the United States, which would have caused to Vespa to completely disappear from the American scene if it weren't for the enthusiasts who kept the vintage scooters on the road by rebuilding and restoring them.
Vespa is Italian for wasp, and it was adopted as a name for the vehicle in reference to its habitus: thicker rear part connected to the front part by a narrow waist, and the steering rod as the antennae.