Gilera B300: Arcore’s first road twin

The Gilera B300 was the first road-going twin built by the Arcore factory and stayed in production, in several versions, from 1953 to 1969. It was conceived as a cheaper, less sporting alternative to the 250 twins of Parilla, Benelli and MotoBi, and its engine simply joined two cylinders of the 150.

Gilera B300 at a glance

based on one source (Italian Wikipedia).

History of the Gilera B300

A twin for the masses

The B300 was the first road twin from the Arcore factory and replaced the Nettuno, a 250 cm³ introduced in 1946 that had not been a success. Its engine came from joining two cylinders of the 150 of 1952, with some mechanical changes. The original model was joined in 1957 by the more powerful “Extra” and by the “Export”, reduced to 250 cm³ and intended almost exclusively for export. The model was revised as a whole in 1963 and the range was completed the following year by the “America” version.

Giuseppe Gilera set the characteristics and the limits of the new bike himself. The B300 was meant to fight the 250 twins of Parilla, Benelli and MotoBi, but as a less sporting machine, better suited to touring and to work, and above all cheaper. It went on sale at 318,000 lire, which let it compete even with the single-cylinder Moto Guzzi Airone, the dominant quarter-litre of the period in Italy.

Built to a price

The engine was designed for economy and simplicity, reusing as many parts already in production as possible and avoiding technical refinements that would have raised costs. The basic decision was to pair two four-stroke engines of the type designed in 1948 by Piero Remor, shortly before his dramatic departure from Gilera.

The result was a fragile machine whose engine showed many faults, small and large: leaks, carburation difficulties, cooling problems and a congenitally weak crankcase. The immediate sales success, much of it from public fleets for municipal police forces, turned into a financial problem for Gilera, because machines kept coming back to the factory for replacement and warranty repairs in numbers large enough to disturb normal production. Gilera was forced to redesign the engine quickly, which cured most of the problems of the early series.

Fifteen years on the list

Despite its defects, the convenient price gave the B300 a good spread and kept it on the price list for more than fifteen years, through the Extra, Export, the 1963 revision and the America of 1964.

At the Milan motorcycle show Carlo Guzzi, looking at how sparsely the B300 was built and finished, turned to his friend Giuseppe Gilera and said in Milanese: “Brao Pepin; de men de inscì te pudevet minga metegh denter” — “Bravo Giuseppe, you couldn’t have put less into it.”

Design and features

• First road twin from Arcore: two 150 cylinders joined in one crankcase.
• Low price: 318,000 lire at launch, close to a quarter-litre single.
• Touring rather than sport: built for everyday use and work, not for racing.
• Public fleets: many municipal police forces bought the B300.
• Quick redesign: early engines were fragile, and Gilera reworked them to cure most faults.

Gilera B300 versions

• B300 (1953): the original model.
• Extra (1957): the more powerful version.
• Export (1957): reduced to 250 cm³ for export markets.
• 1963 revision: the model revised as a whole.
• America (1964): the version that completed the range.

The B300 engine grew out of the 125-150-175 family, and the Gilera four-strokes that followed it are described with the Saturno. More models are in the Gilera collection.

Video: Gilera B300 laufend / running

Video by hatogo1 on YouTube.

Sources

• Gilera B300, Italian Wikipedia: production years, versions, price, engine origins, warranty problems, Guzzi anecdote