Motobecane port database
Motobecane Port Database
Motobecane mopeds, like many other mopeds, were produced with a series of speed ratings. It is generally accepted that there were 20, 25, and 30mph versions, but there is much speculation as to how these models are classified. Some state that the speed is designated on the front VIN tag, classified as A, B, or C. A counter argument states that that system varies from year to year. Others claim the model type can be determined by the shape of the fins on the cylinder. Some are simply referred to as "fast" or "slow". A new theory proposes the cylinder speed is simply stamped into the side of the cylinder in a "CSxx" format, where CS30 would designate a 30 mph model.
Below is a list of documented port maps from various cylinders, submitted by their owners. Each diagram provides the year, model, length and width of each port, the vertical distance from the top of the cylinder, as well as any cylinder designations. The measurements were all asked to be taken within +/- 1 mm of accuracy, but the accuracy of each drawing can only be verified by the mapper. The only map I can personally account for in terms of accuracy is the diagram mapped by S. Pamboukes. The diagrams are catalogued chronologically.