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 Terrot - Flat twin Cuzeau
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Terrot D2-492-86-06
Photo ou archives : Cl. Reynaud

Capacity : 350
Model : Flat twin Cuzeau
Production : 1916 - 1920
Category : (R) Street Bike


350cc Cuzeau Flat-Twin - 1920

Too advanced to survive

After WWI, Terrot recommenced production with modest two-stroke singles but developed ambitious projects like this extraordinarily original flat-twin two-stroke.

Working for the Army

A renowned engineer and racer, Henri Cuzeau was demobilized in 1915 to work at Terror on the MAG-engined Motorette destined for use by the French Army.

Top-Hat Pistons

During WWI, Cuzeau also designed this flat-twin, which was built in 1919, but the Terrot Cuzeau was too advanced in concept and never passed the prototype stage. While there were many flat-twin engines at that time, the Cuzeau was the only two-stroke, and that wasn't its only originality. In a two-stroke single, the descending piston compresses the gas admitted into the crankcase, but this principle doesn't work in a flat-twin. For while one piston is trying to compress the gas, the other is rising in its cylinder, nullifying the work of the first. Like the English Dunelt Company on its 1919 singles, Cuzeau used double-diameter pistons in which the upper part functioned normally while the lower section precompressed the gas admitted into the crankcase into a holding chamber above the piston skirt until it was allowed into the combustion chamber by the transfer ports. The frame was just as original, for in place of the classic twin top tubes with a tank between, it had a load-bearing gas tank welded between steering head and saddle pillar. The gasoline ran down inside the saddle pillar, at the base of which was a tap – the gas tank was pressurized by a hand pump so that the fuel was force-fed to the carburetor.


Engine: 350cc (60/85x62mm) air-cooled flat-twin; single-throw crank; magneto ignition

Valves: two-stroke

Fuel System: carburetor; crankcase intake, precompression by lower (larger) part of piston

Transmission: 2-speed, chain final drive

Suspension: swing arm (front); rigid (rear)

Brakes: twin-shoes on dummy belt-rim (rear)

Too complex, the Terrot flat-twin never passed the prototype stage, and only two or three examples were built.

Motorcycle encyclopedia Moto Passion, realised by François-Marie Dumas, include almost 2000 photos presented with an exhaustive history of the motorcycles exhibited.

This unique collection has been realised with the participation of many specialists. With many thanks in particular to Yves Campion, Michael Dregni, Didier Ganneau, Jean Goyard, Helmut Krackowizer, Michel Montange, Christian Rey, Bernard Salvat, Mick Woollett, etc

One can order here

  • Original cards on paper (in french)
  • High resolution scans or original documents presented and signed with my name.

Please contact me at for conditions and copyright.

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François-Marie Dumas

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