Adler MB 250 RS

Make Model.	Adler MB 250 RS
Year	1953
Engine	2 cylinder, 2 stroke, flat-crowned pistons
Capacity	247 cc / 15.1 cub in.
Bore x Stroke	54 x 54 mm
Cooling	Air cooled
Lubrication	Petrol oil mix 25:1
Clutch	Multi plate
Starting	Kick start
Battery	6V, 6Ah
Ignition	Bosch coil
Carburetor	Twin Bing carburetors
Exhaust System	Twin, steel, chrome
Max Power	19.2 kW / 26 hp @ 7500 rpm
Compression Ratio	1: 5.75
Clutch	Multi disc
Transmission	4 Speed gearbox housed in engine block, foot gearchange
Final Drive	Chain
Frame	Double tubular frame with sidecar adapter.
Front suspension	Twin swinging leading link forks with shock absorber and steering damper
Rear suspension	Swinging fork adjustable for load and road conditions
Tyres (front and back)	3.25 x 16 in.
Brakes (front and back)	Drums, 180 mm diameter
Wheelbase	1257 mm / 49.5 in.
Dry Weight	98 kg / 216 lbs
Fuel Capacity	12 L / 3.2 US gal
Reserve	3.8 L / 1 US gal
Average Consumption	3.6 l/100 km / 27.8 km/l / 65.3 US mpg
Top Speed	169 km/h / 105 mph

In 1949, Adler was one of the first German marques to recommence production after the war. Right up to end of manufacture in 1957, it remained unapproachable as a maker of two strokes. Late in 1952, Adler unveiled the MB 250, a tw0 stroke twin which quickly became known as the "Cannonball." It was equally successful as a touring bike, a sports bike and an off roader. But it was particularly successful under another name, for the first Yamaha twin (the YD 1 of 1957) was more or less a direct copy of the Adler MB and the subsequent Yamaha twins have followed its pattern.

A Fabulous Two Stroke Twin
Soon the touring MB 250 was joined by the sporting 250 S, then by a racing version, the 250 RS with twin carburetors and swinging fork rear suspension instead of plungers. The 250 RS of 1954, still air cooled, developed 26 hp @ 7500 rpm, weighted 216 lb and was capable of more than 105 mph. Highly prized in its native Germany, the Adler RS enjoyed a rare foreign success in France's Bol d'Or in 1954, where a solo RS and another with a side car won their respective under 350cc categories.

Adler takes to Water
Beginning in 1954, tuner/rider Hellmut Hallmeier perfected a water cooled 250 RS, whose highly successful racing career continued into the sixties. The last "works" RS Adlers ridden by Walter Vogel and Hellmut Hallmeier developed 39 hp at over 10,000 rpm with a top speed of 125 mph.