The name "Agmar" on the tank is that of the owner.
A Brief History of the Marque
Manufactured: 1905-1914
Founded by Luigi Semeria, the company produced its first motorcycle in 1907. It is a machine with a 262cc engine with 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.
Report from the 1912 Olympia Show
1913 model 2 ½ h.p. S.I.A.M.T. fitted with overhead valves.
The fitting of the exhaust pipe used on the 2 ½ h.p. S.L.A.M.T. Note the method of attaching the silencer.
Radium S.I.A.M.T. (Stand 23) - The interesting S.I.A.M.T. motor bicycle has been considerably improved, and has now been made thoroughly to conform to English ideas.
The loop frame is maintained, but the top tube is dropped so as to allow of a very low saddle position. Spring forks are fitted: though the model illustrated has S.I.A.M.T. forks; Druid forks will be fitted to order. The engine, with its ingenious detachable head, which carries the valves and valve tappets, remains unaltered, but the new exhaust pipe which is 1 3/8in. internal diameter, is now brought through an eyelet in the tube of the frame to a new aluminium silencer, fitted with a foot-operated cut-out.
The silencer union also carries a bracket, through which the adjuster of the Bowden exhaust lifter passes: Aluminium footrests are fitted.
It will be noticed that the front mud-guard is provided with side shields, and that similar shields are fitted to the lower half of the rear mudguard. This mudguard is halved, and the carrier is attached to it, so that three parts of the mudguard can be swung out of the way, allowing a large portion of the circumference of the tyre to be exposed. The carrier is strongly constructed, and suitable for carrying luggage. Both brakes are hand operated, and are applied, one to the inside and the other to the outside of the belt rim. The tank has also been improved in outward design. The finish of the engine is particularly good. The Villiers two-speed hub can be fitted if desired. The Radium S.I.A.M.T. Co. are shortly introducing a 3 ½ h.p. twin, 68 x 68.8 mm. = 498 c.c. This machine has obtained several successes in open competition since its introduction into this country, and many more in Italy, its country of origin.
The Motor Cycle, November 21st 1912
Ozebook, MC Storico Conti and others have images of SIAMT 500cc V-twins.
Sources: MC Storico Conti, ozebook, Henshaw, The Motor Cycle, et al.