A fascinating prototype that never made it into production, the MV Agusta 300B seemed set to unlock the future.
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.
MV’s 300B had potential, but only a prototype was made as factory management considered the production costs too great. It disappeared for 50 years, and then emerged in an amazing postscript.
In the mid-1950s, MV Agusta was alive with innovation. Its first 500cc Grand Prix title was just around the corner and the Italian manufacturer was challenging for titles in the smaller classes when the factory displayed the MV 300 Bicilindrica at the 1955 Milan Motorcycle Show.
This exciting all-new twin was designed to compete with the Gilera B300, but looking back, it seems MV had taken a gun to a knife fight. Gilera had been on a roll since taking the 500cc world title in 1952 with its double overhead cam inline four. Late that year it had debuted what it described as a sporting twin, the 305cc Gilera B300. Sure, the B300 had its cylinders inclined forward a rakish 10 degrees, but the rest of the specification was fairly mundane. Unit construction of engine and gearbox was a big step forward, but the engine was a low-compression, single-cam, two-valve-per-cylinder workhorse that wasn’t without issues.
Owners of early B300s complained of overheating engines and main bearing failures. Improvements were made and the model lasted until 1964, but it wasn’t a world beater.
Nevertheless, MV recognized that Gilera was weaning Italian riders away from single-cylinder motorcycles, so it decided to bring in a big gun and mount a challenge. That big gun was Carlo Gianini, the man who had designed the 4-cylinder Gilera Rondine in the 1930s. One of the most powerful motorcycles of its era, the Rondine developed nearly 90 horsepower and set the 1937 world speed record at 171mph (275kmh).
More recently, Gianini had worked with Moto Guzzi to create its inline 4-cylinder rival to Gilera and MV in 1952, which was raced until 1954. The engine was mounted longitudinally and originally fitted with rudimentary fuel injection. However, shaft drive and an overly complex design blighted its potential for GP race success.
Nevertheless, Gianini was still the go-to man for new designs, and Count Agusta came knocking. The result was a technically stunning engine, especially compared to the rather mundane Gilera B300. Unit construction of the engine and 4-speed gearbox formed a solid basis, but after that things got decidedly different.
Unlike most parallel twins of the time, the MV 300B’s cylinders were separate castings, set far apart to encourage air flow to achieve the best cooling. Sandwiched between them was a central tower of gears driving the valve actuation.
The electric starter was bolted to the rear of the transmission, and to keep the engine as narrow as possible the clutch was driven from a gear cut into the crankshaft, and the generator, distributor and oil pump were all driven by shaft and helical gears. The generator was horizontally mounted in front of the crankcase, its shaft driven by a jackshaft off the crank. The distributor was vertically mounted behind the cylinders, taking its drive from the same jackshaft that drove the generator. In the same line as the distributor, a shaft ran down to the oil pump mounted at the bottom of the sump. Oil was kept in the crankcase, rather than in a separate oil tank.
All this was fairly innovative, but perhaps the most fascinating feature was the valve actuation mechanism. Cam drive was via two large gears, one above the other and driven from a gear on the crankshaft between the cylinders. The top gear featured a single cam lobe on either side, against which lever followers operated short valve actuating pushrods that were parallel in one plane to the valves, set at a 90-degree included angle in the hemispherical cylinder head combustion chamber. The pushrods were very short and therefore light and strong.
All this may sound quite revolutionary, but elements of this design had already been seen in radial aircraft engines. A vaguely similar system had also appeared on the Parilla 175 in 1953.
The twin was well received by show attendees. MV claimed its power output was around 20 horsepower, some 7 horsepower more than its Gilera rival. It also looked like it had just come off the race track. Twin carburetors, cylinders inclined 45 degrees forward, beautiful swooping exhausts and generous radial fins in the heads screamed performance. Even the Earles forks had been developed specifically for this model.
Sadly, Carlo Gianini’s feat of engineering was a dead end for MV. Only the prototype was built, as Count Agusta realized it would have been way too expensive to put into production and sell as an affordable road bike.
“The MV300B contains design elements unusual but not unheard of at the time,” says Ian “Gowie” Gowanloch, founder of international parts business Ital-Spares. “I owned a Gilera B300 when I was living in Italy. It was without doubt one of the most inelegant pieces of design I have ever seen. That the MV 300B was conceived as competition seems incredible; they are opposite ends of the spectrum.
“The MV 300B is different from normal everywhere you look. It is also immediately obvious why the basic elements have not been copied. Very little of the exercise is simple and cost effective, either to manufacture or assemble.”
Technically, it left Gilera’s twin in the shade, but its ultimate failure was its over-design. It was simply too much technology; too complicated to tool up for a dedicated production line and too difficult for non-specialist mechanics to maintain. And so the prototype was pushed aside and forgotten.
However, development of a racing version was started. This also was ahead of its time, with a tubular triangulated space frame inspired by contemporary F1 car Grand Prix chassis design. It was another brave attempt, but MV decided it would be uncompetitive when compared with the company’s existing racers, and while MV would eventually go on to produce twin-cylinder road models in the 1960s and 1970s, they were nothing like the 300B.
The man known simply as Mr. Elli is universally recognized as a savior of MV history and the visionary who brought most of it back to life again. Ubaldo Elli died last year, but he, American Robert Iannucci (of Team Obsolete) and Britain’s John Surtees were the main buyers of MV heritage when the famous race shop was sold off in the 1980s.
Mr. Elli spent the next few decades turning his collection into a running museum that toured the world, often with some of the original racers in the saddle. He also took on the hardest job: rebuilding the MV 300B, which had come into his ownership, and getting it running.
It was soon discovered that the engine had no internals, and in fact appeared to never have had any! No matter, in 2013 he handed the project over to Ginetto Clerici. Soon Enrico Sironi, director of the MV museum at Cascina Costa, was involved, and a long paper chase uncovered drawings of the engine. Suddenly, it seemed possible that the missing pieces could be manufactured.
They were, and in a testament to the craftsmanship and enthusiasm of Italy’s motorcycle manufacturing industry, the 300B is finally running. What man has made, man can make again. MC
Dead ends and false starts: BSA, Harley and Indian
BSA’s dead end: In the U.K., BSA’s industry-leading designers Bert Hopwood and Doug Hele developed the innovative MC1 250cc prototype in 1954. Its double overhead cam, horizontally mounted single-cylinder design featured bevel-gear-driven camshafts and four radial valves. Intended as the potential basis for a family of sophisticated racing and road models, it was stillborn.
Harley designed a winner, then forgot about it: When Harley-Davidson finally decided to build its overhead-valve Sportster in the 1950s, it dug out a pre-war prototype test mule. Based on a flathead 45, it had logged more than 4,000 miles of road testing in 1939.
Electric dreams: Indian invented the first electric starter for a motorcycle back in 1914. Available on that year’s Hendee Special, by 1915 it had already been taken off the option list, a victim of the limitations of the battery technology of the day; the batteries were exhausted after a dozen or so starts and the charging system couldn’t keep them up. It wasn’t until the early 1960s that Japanese motorcycle manufacturers would bring the electric starter to market on their early small-capacity models.