Twin Dreams: 1955 MV Agusta 300B Bicilindrica Prototype

A fascinating prototype that never made it into production, the MV Agusta 300B seemed set to unlock the future.

| September/October 2017

  • 1955 MV Agusta 300B Prototype
    Photo by Phil Aynsley
  • 1955 MV Agusta 300B Prototype
    Photo by Phil Aynsley
  • 1955 MV Agusta 300B Prototype
    Photo by Phil Aynsley
  • The 300B’s overall styling was similar to MV’s Tourismo Rapido, but the 300B had a unique frame and Earles fork front end.
    Photo by Phil Aynsley
  • The 300B’s overall styling was similar to MV’s Tourismo Rapido, but the 300B had a unique frame and Earles fork front end.
    Photo by Phil Aynsley
  • Carburetion on the 300B was via twin 20mm Dell’Ortos. The vertical distributor was driven off a jackshaft on the crankshaft.
    Photo by Phil Aynsley
  • Rockerarm boxes on the forward-inclined parallel twin make it look like it has double overhead camshafts; it doesn’t.
    Photo by Phil Aynsley
  • Rockerarm boxes on the forward-inclined parallel twin make it look like it has double overhead camshafts; it doesn’t.
    Photo by Phil Aynsley
  • Indian offered the first electric starter on a motorcycle in 1914.
    Photo by Phil Aynsley
  • BSA’s clever 4-valve overhead cam single.
    Photo by Phil Aynsley

1955 MV Agusta 300B Prototype
Engine:
294.8cc air-cooled high-cam parallel twin, 57mm x 57.8mm bore and stroke, 8:1 compression ratio, 20hp @ 8,000rpm
Carburetion:
Two 20mm Dell’Orto
Transmission:
4-speed, chain final drive
Electrics:
6v, coil and breaker points distributor ignition
Frame/wheelbase:
Pressed steel w/dual downtube steel cradle/52in (1,320mm)
Suspension:
Earles fork front, twin shocks rear
Brakes:
7.1in (180mm) SLS drum front and rear
Tires:
3 x 19in front, 3.5 x 19in rear
Weight (dry):
308lb (140kg)
Fuel capacity:
4.8gal (18ltr)

Engineers and designers are always pushing the envelope of reality, sometimes ending up with crazy ideas. Remember the various hub-center-steering prototypes of the 1980s? These days, we have self-balancing-motorcycle designs being promoted by BMW and Honda.

The motorcycling world hasn’t gone mad. It’s always been like this, and our two-wheeled history is littered with prototypes, some successful, some not. It’s a pattern you can date right back to the steam-powered cycle designs of the 1860s.

One fascinating prototype that never made it into production is MV Agusta’s 300B of 1955, a motorcycle that seemed set to unlock the future, with advanced features such as electric-only starting and high camshafts with very short pushrods.



Today, we take electric-start-only for granted and the high-cam, short-pushrod design long ago reappeared in BMW’s all-new “oilhead” boxer twin engine of 1993.

But things were very different back in the early 1950s. The world was finally shaking off the devastation of World War II and motorcycles were getting bigger in capacity and more sophisticated. From Harley-Davidson’s new road-burning overhead-valve Sportster to Moto Guzzi’s fiendishly complicated V8 500cc Grand Prix racer, the motorcycle world was jumping with big, new ideas.



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