Marcel Violet built a C.S.V. (Compagnie des Scooters Violet?) scooter with a twin-cylinder two-stroke engine which had a single combustion chamber and a single spark plug, commissioned by the Bucciali brothers. By 1923 this had developed into a 125cc scooter which raced at the Bol d'Or achieving an average of 59 km/h.
He was also one of those responsible for the Sevitame
Sources: bernardet.com, zhumoristenouveau.eklablog.com