A Brief History of the Marque
Founded by Luigi Semeria, the company producded its first motorcycle in 1907. It is a machine with a 262cc engine wiht large valves and a conical combustion chamber, rated at 2.75 hp. In 1913 their catalogue listed a single cylinder 344cc model of 1 CV, a twin-cylinder 494cc model of 4.5 hp and a twin-cylinder 7 hp 688cc model. In 1914 they revealed a 344cc model delivering 2.75 CV, together with a single cylinder 262cc of 2.25 hp and a twin-cylinder 731cc engine with power of 6-7 hp. Later that year the war came and their business ceased.
Ozebook, MC Storico Conti and others have images of different SIAMT 500cc V-twins.
Sources: MC Storico Conti, ozebook, Henshaw, et al.