A Brief History of the Marque
Manufactured by Soc. Italiana Motocicli a Nafta Mariani, Milan, 1932-34
Enrico Mariani built motorcycles powered by 498cc sidevalve single-cylinder engines with either 2 valves for petrol or 3 valves for naptha.
The tube that carries naptha oil from the tank to the carburettor passes twice over the cylinder head, heating the naphtha. It possibly may also have run on alcohol.
Apparently the first example of this type of engine, it drove via a Burman three-speed gearbox.
NB. Mfg dates vary, Tragatsch giving 1930-34
Sources: MC Storico Conti, Tragatsch p200