Report From Italy
REPORT FROM ITALY
CARLO PERELLI
A VISIT TO THE museums of Gilera and Moto Guzzi, Italy's biggest motorcycle manufacturers, developed nostalgic memories for two fabulous racing machines which made their mark in history for their original, advanced, excellent design. The two models are the Moto Guzzi 500cc V-twin and the water-cooled, supercharged Gilera four, pictured in the accompanying photographs at the peak of their development. The Moto Guzzi was conceived as far back as 1933, adding another cylinder (in what was believed to be the best position for engine balance, cooling and least frontal area) to the successful horizontal 250 single. On the five hundred the second cylinder was set at 120 degrees, inclined backwards 30° from vertical. Single overhead cams operated by shafts and bevel gears on the right side of the engine. Bore and stroke were also traditional; "square" at 68 x 68 x 2 = 494.8cc. The magneto was placed between the cylinders and gear-driven on the right. Another "classic" for Moto Guzzi, the external flywheel on the left, was retained. Also on the left was the gear primary drive to the clutch. A four-speed gearbox was pedal-controlled from the right. Although not as fast as the pre-war supercharged bikes or the post-war fours, the V-twin had good acceleration which gave quite an advantage on winding courses. Stanley Woods won the 1935 Isle of Man Senior T.T. with it. Omobono Tenni just missed winning the 1948 race with plug trouble after having set the fastest lap. In 1949, this time with English rider Bob Foster, the Moto Guzzi V-twin lost the Senior T.T. after recording fastest lap, because of a split flywheel! In Italy it won several Championship and long distance races. The late Fergus Anderson rode brilliantly to win the Swiss GP at Berne in a downpour in 1951, the last big victory before retiring the V-twin.
Through the years until 1952, when the machine was put in the museum at the end of its glorious career, power stepped up from the original 44 at 7000 rpm to 47 at 8000 rpm. The increase might not seem high, but before the war it was allowed to run on alcohol-based fuels, while after the war only pump fuel could be used. In fact, detuning the machine after the war for the new type of fuel dropped power to 42 at 6800 rpm. The original weight of 332 pounds had been lowered to 318 pounds in spite of a stronger layout and the introduction of rear suspension. The rear swinging fork acted on a pair of springs set horizontally under the crankcase (Moto Guzzi was one of the first to fit rear suspensions to both racing and roadster bikes). Top speed was raised from 105 to over 130 mph without streamlining.
The Gilera Four was born in 1936 on the basis of a previous model built in Rome. Water-cooled cylinders were inclined at 45° and the valves set at 90 degrees, operated by two overhead cams driven by a train of gears between the middle cylinders. This drive also operated the Rootes-type supercharger and magneto. Primary drive was by gears to a fourspeed gearbox in unit. Bore and stroke were 52 x 58 x 4 = 492.7cc. The combination pressed steel and tube double cradle frame had girder front forks and swinging arms at the rear acting on two coil springs set at the base of the rear fender. Power was 80 bhp at 9000 rpm for a top speed of 135 mph. With a total dry weight of 352 pounds, it was essentially a high speed machine, not so handy and easy to ride on twisty courses. Piero Taruffi set several high speed records, among them the world's record at 171 mph and the "one hour" record at 156 mph, which was broken in 1953 by Ray Amm on a Norton.
In 1939 Dorino Serafini won the European Championship with the Gilera; in the meantime power had been stepped up to 85 at 9500 rpm and top speed was over 145 mph. Deprived of the supercharger, and on pump fuel fed by only two carburetors, power dropped back to 50 bhp. The Gilera Four was still able to win in Italy, in both solo and sidecar races, until superseded in 1948 by the air-cooled version.
