Simson AWO 425, 250 cc (1957). 

Simson was a German company which produced firearms, automobiles, bicycles and motorcycles, and mopeds. Under the Third Reich, the factory was taken from the Jewish Simson family, and was renamed several times under Nazi and later Communist control. The Simson name was reintroduced as a brand name for mopeds produced at the factory in the former German Democratic Republic (GDR). Simson mopeds were then produced in Suhl (Germany) until 2002.

1949–62: four-stroke motorcycles

The USSR handed control of the factory to the German Democratic Republic (DDR) and in 1952 it was renamed Volkseigener Betrieb Fahrzeug- und Gerätewerk Simson Suhl. Production of sporting guns, prams and bicycles slowly resumed, but the main focus was again on making motorcycles.

Between 1949 and 1962 the Suhl factory produced more than 209,000 four-stroke motorcycles. They were designated 425, derived from the fact that they had a four-stroke engine with 250 cc displacement. The 425 has overhead valves in a V-formation, has a four-speed transmission, shaft final drive and has a duplex cradle frame. It earned a high reputation in the Eastern Bloc countries.

The motorcycles were branded AWO (an abbreviation of Awtowelo) from 1949 until 1955, when the Simson name was revived. Some had Stoye sidecars fitted, and a Stoye Campi luggage trailer could also be fitted.

The original 425 model had plunger rear suspension, a 6.7:1 compression ratio, produced 12 bhp and had a top speed of 100 km/h (62 mph).

It had 19 in (480 mm) wheels with half-width drum brakes. The first 1,000 machines were built from July 1949 until December 1950, and all were exported to the USSR. The model was released to the DDR domestic market in 1951.

The plunger-framed model was designated AWO 425 from 1949 until 1955 and Simson 425 T from 1955 until 1960.

The “T” stands for “Touring”, to distinguish it from the Simson 425 S (Sport) model introduced in 1955. The plunger model was made from 1949 until 1960 and a total of 124,000 were built.

The 425 S had a twin-shock swinging arm rear suspension and a top speed of 110 km/h (68 mph). It had 18 in (460 mm) wheels with 180 mm (7.1 in) full-width drum brakes to give it better acceleration and braking than the plunger model. Initially the 425 S had 7.2:1 compression and produced 14 bhp; in 1961 this was increased to 8.3:1 which increased power output to 15.5 bhp.

Simson made the 425 S from 1955 until 1962 and a total of 85,000 were built.

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