The photos below are of a running four stroke, 2 valve prototype engine, as specified by the designer of the Vespa, D’Ascanio. The story goes, that Enrico Piaggio rejected the advanced four stroke, for a simpler and less expensive two stroke engine.
He wanted shade tree mechanics to be able to work on the engines, and have them be simple enough that it was easy and inexpensive to keep them on the road. So perhaps this settles the age old (well since the introduction of the four stroke Leader engine) debate between vintage and modern enthusiasts over whether a four stroke Vespa is a “real” Vespa. According to D’Ascanio, he who gave us this fabulous mix of art and utility called Vespa, the answer is a resounding yes.
Vespa Four Stroke Prototype: Vespa World Club President, Marco Manzoli, shows us the finer points of the four stroke prototype.
Crank Driven Camshaft: In this side shot, you can see the crank driven cam that actuated the pushrods up to the exposed valve train. Pretty tidy design for the day.
Valve train: Easy to adjust the valves in this configuration!