hi I think I'm right in saying in the days of hailwood and his 4cylinder Honda, Benelli had a single cylinder 250cc four stroke twin cam gear driven engine up to 140 mph on the island and would have beaten the honda but for either petrol or chain break memory not as good as it was perhaps some one would like to do some research and follow this up cheers mike
Benelli made a supercharged 4 cylinder 250 in 1939, but a few world troubles stopped it being raced until 1949, then in 1950 supercharging was banned and Benelli replaced it with a single winning the world title 250cc in 1950 with rider Dario Ambrosini. During the sixities Tarquinio Provini and Renzo Pasolini had many successes on the Benelli. Aussie Kel Caruthers won the 1969 title on a Benelli 250 four cylinder. (Taken from the Encyclopedia of Motorcycles).
For the 1959 season Benelli produced a new, short-stroke 250cc engine, which produced 33 to 25bhp at 10,200rm. The 250 single achieved one major success when Geoff Duke rode to victory in the 1959 Swiss GP, one of his last wins before his retirement. The one you see here is a 1958 Benelli GPX1003, one of only four constructed Benelli 250cc singles and built originally for the 1959 season. £200,000 asking price in 2012
I reckon that's the one I'm looking for info on the one also used in the tt when I believe it would have won except on the last lap it failed to Finnish but well done for the info so far the train of gears is what I recognise from the benelli Cheers mikr