The "S.A. des Ateliers Gillet" was founded november 8th 1919. Their purpose was to build motorcycles. The company was located in Herstal, at the rue Hayeneux, in the former Auto-Mixte buildings. The main shareholder was a wholesaler in wood, Desiré Gillet, who financed the buildings and research, became chairman, and his son Léon became managing director.
The founders set out to build high-quality motorcycles. Engineer Fernand Laguesse had been busy building a prototype. He'd been working on it during the 1st worldwar. Testing and fine-tuning was done in 1919. In that same year modern factory equipment was bought in the USA. In may 1920 the factory almost doubled in size, from 4000 to 7000 m2, by acquiring a neighbouring building. The first batch of motorcycles left the factory in may 1920. Production capacity then was 5 bikes per day.
The 300cc Gillet, drawn by Laguesse, was ingenious yet simple and robust. The single cylinder 2-stroke engine, with 3 ports, 74x70 mm, 300cc had an integral 2 gear gearbox. The unit could be removed by removing only 6 nuts. The bike had a plate-clutch and a belt-drive. Starting was done by kickstarter. The bike weighed 80 kg, and cost 3250 francs. Laguesse had chosen to use a 2-stroke, although that system then was much critisized, because a lot of 2-strokes of that day had severe problems with the sealing of the crankcase. Laguesse had thought out a system using mechanical seals, which guaranteed a perfect air-tight seal, even after a longer period. The 2-stroke motorcycle became an instant success.
Right from the start the company entered their bikes in races, to get the brand name established. Of 12 machines entered in Liège-Paris-Liège 3 weres Gillet-Herstals. They finished 1st, 2nd, and 4th of in total only 4 machines making it to the finish.
In 1921 the 300 became available in 2 versions; the 'de luxe', and the 'sport' (less expensive, no kickstarter, no clutch). At the GP of Belgium, which took place at Francorchamps in august (for the very first time) Kiecken en Destrebecq (on Gillets) were 1st. In France Kiecken won Paris-Les Pyrenées-Paris on a 350.
In 1922 the '350cc tourisme' came out; technically almost the same, but 79.5x70mm, or 348 cc. This bike cost 4000 fr. March 19th the 5 man Gillet team won the Coupe de la Meuse, and in may Reynartz and Dubois won 1st and 2nd place in the 350cc class in Liège-Nice-Liège.
In 1923 2 new 350 models came out, one of these had a special frame, designed for ladies and clergy (sp ??). On this last version the engine was covered, which wasn't too beneficial for its expected service life. The other (350 sport) had a stronger engine, with a rotating inlet valve, directly driven by the crankshaft. It connected the carburettor to the sump, and made it possible to use the entire up-stroke of the piston to suck the mixture into the sump. The cooling fins of the engine were slightly smaller than those of the previous model, because this new bike was faster, and therefore better cooled. It's top speed was 110 km/h. This year Gillet became champion of France, thanks to the achievements of Hufkens, Renier, Gheude en Reynartz in the Tour de France, and thanks to Hufkens who was the only rider in Paris-Les Pyrenées-Paris who didn't score any penalty points. In 1924 Frenchman Robert Sexé drove Paris-Constantinople-Paris, with a 350 sport. In 1925 Kiecken won 2nd place in the Belgian GP, on a 350.
In the meantime Laguesse had been working on anther type of 2-stroke. It had 2 opposed pistons in one cylinder, and was watercooled. 54x150 mm, 26 hp, 344 cc. This meant 74 hp per litre, massive power, considering the period (1926!). Top speed was 150 km/h. Unfortunately the period sparkplugs couldn't cope with the amounts of heat generated, so the bike couldn't run any serious distances, which was detrimental to further development of this machine. Kiecken won 1st place in the Mont-Theux hillclimb, at 118 km/h. Finally the tuning etc. evolved, and the bike was entered in the French Bol d'Or of 1926. In 1927 Kiecken made 107.740 km/h in the hillclimb of Spa-Malchamps. The constant and expensive tweaking, tuning and testing by Laguesse led to a serious difference of opinion between Laguess and Léon Gillet. Fernand Laguesse left Gillet in 1927, to start his own company, and Léon Gillet had the opposed piston machine, and all parts destroyed...
In 1920 Gillet also sold a 600cc four-stroke, and a V-twin of 750cc, meant as a side-car machine. The engine was made by MAG, in Geneva. The 750 was replaced by a 996cc (82x94) MAG with Burman gearbox in 1922. These machines were in the catalogues till around 1925.
The Frenchmen Andrieux en Sexé, each on a 350 Sport, drove around the world, from june to december 1926. They went via Paris, Moscow, Siberia, Japan, the USA to New York, some 25000 km total. The bikes were normal, standard machines, but fitted with larger tanks, reinforced wheels, and wider tires. They took 2 chainsprockets, a shockdamper plus front-fork, and 2 tanks with them for spares. Both riders and bikes survived the ordeal in great shape. The bikes were riden for a long time after this trip, one had 130000 km on the odometer in march 1928, the other more than 150000, both bikes still had their original parts
In 1928 the "Tour du Monde", as the 350 was called by then, was improved, and was sold in a form which would hardly change from then on. The cooling-fins of the cylinder were enlarged, as was the diameter of the drum brakes. Also the tank had a larger capacity, and the front fork was improved. The machine was still very simple, and (therefore) robust.
From 1933 on the standard 350 had a 2 speed gearbox, and 85 km/h top speed. The sport version had an aluminium cylinderhead and piston, a 3 speed gearbox, and 95 km/h top speed. In 1937 the bike was delivered with "Neimann-suspension" (rubber rings). The 2 speed model disappeared in 1938.
