With Phil Aynsley
One of the most iconic of all 500cc Grand Prix bikes was Carlo Guzzi’s 120º V-twin. The failure of the 1931 supercharged straight four (featured in column 115 – link) and the age of the 4VSS horizontal single meant something new was required, so Guzzi turned to his very successful 250 for inspiration.
Moto Guzzi Bicilindrica 120º V-twin GP Racer
A second cylinder was added at 120º behind the horizontal front cylinder. The balanced combination of power and agility was to prove a winner with the basic design being used up until 1951!
Moto Guzzi Bicilindrica 120º V-twin GP Racer 
Moto Guzzi Bicilindrica 120º V-twin GP Racer
The Bicilindrica’s first race was the 1933 Italian GP with three entered and one finishing second. A rigid frame and Brampton forks held the 41 hp (at 7000 rpm) motor.
Moto Guzzi Bicilindrica 120º V-twin GP Racer 
Moto Guzzi Bicilindrica 120º V-twin GP Racer
Weight was 160 kg and top speed 185 km/h. Using electron for the crankcases the following year saw the weight drop to 151 kg and output was raised to just over 43 hp.
Moto Guzzi Bicilindrica 120º V-twin GP Racer
Development continued with a sprung frame appearing in 1935 which was used by Stanley Woods to record the first win by an Italian manufacturer in the Isle of Man’s Senior race.
Moto Guzzi Bicilindrica 120º V-twin GP Racer
The Bicilindrica continued to be raced until the war intervened, although the supercharged BMWs dominated this period. The banning of forced induction when racing resumed after the war saw the venerable V-twin brought out of retirement.
Moto Guzzi Bicilindrica 120º V-twin GP Racer 
Moto Guzzi Bicilindrica 120º V-twin GP Racer
The bike seen here is an early 1946 model that was only slightly updated from the pre war bikes. A much larger front brake was fitted and more engine parts were fashioned from alloy.
Moto Guzzi Bicilindrica 120º V-twin GP Racer
Power was in the region of 46-47 hp and weight around 150-155 kg, while top speed was over 200 km/h.
Moto Guzzi Bicilindrica 120º V-twin GP Racer 
Moto Guzzi Bicilindrica 120º V-twin GP Racer
Source: MCNews.com.au