The 3 CV Royer was a unique creation by J. Royer, an avid motorcyclist and passionate mechanic enthusiast, who debuted his creation in the year 1950. Royer, hailing from Montpellier, shared his innovation with readers through a newspaper, detailing the technical specifications and photographs of his personal project.

Chassis: The base of Royer's creation was a Simca-5 chassis, onto which he executed a complete transformation of the front suspension.

Engine: The original powerplant was a two-stroke, inline twin-cylinder engine with a displacement of 600 cubic centimeters. This German-manufactured engine, branded JLO, was air-cooled.

Ignition and Lighting System: Royer's ingenuity extended to the transformation of the ignition system, utilizing a magneto for ignition and a lighting dynamo, both sourced from Magneto France. A double ignition system, facilitated by a delco distributor, was synchronized with the magneto. Royer implemented manual advance mechanisms, ensuring simultaneous operation. Each cylinder head was meticulously machined to accommodate a second spark plug, providing the option for either single or double ignition. The engine was started manually using a crank.

Carburetor: A new Solex type 508 carburetor was installed to manage fuel delivery.

Gearbox: The transmission system consisted of a Renault-branded gearbox, specifically the type used in the Juva 4 model.

Performance: Despite its bespoke modifications, the 3 CV Royer maintained a respectable speed of 90 kilometers per hour, while consuming a mere 6 liters of fuel.

Construction and Assembly: Remarkably, Royer completed all construction and assembly work within a year, dedicating his leisure time to the project.