Jozef Magnat and Louis Debon started manufacturing bicycles in 1893. In the early 1900s, they experimented with motorized bicycles. By 1906 they had their first in-house engine. By 1911 they had their first OHV in production and by 1912 they were the first French brand to have an OHV in their catalog. This was an OHV in a blind cylinder (no removable cylinder head). With this they were very successful during racing. The French racer Escoffier, who later left Magnat Debon and started his own brand together with Koehler (Koehler Escoffier), further developed this OHV and made one with a removable cylinder head like this one. These were very fast and reliable and won many races. Top speed of these motorcycles was around 100km/h.

In 1930, Magnat Debon was taken over by Terrot and the name was retained but the models were almost identical to Terrot.

This Magnat Debon 400cc OHV racer is such a rare early racer of 1912. First version with the small flat tank, in 1913 came the larger round tank. Motorcycle is complete and engine is loose and has compression. Standard they came with this street version handlebars but many were converted with race handlebars. This motorcycle also has the special racing exhaust with extra valve that one can open.