Report From Italy
REPORT FROM ITALY
CARLO PERELLI
TWO-STROKE disc rotary valve engines for go-karts have been built by various Italian factories for some years. but interest in this appealing, high performance type of engine in the motorcycle field only started about a year and a half ago. It led to the introduction of a 125cc Grand Prix Mondial which failed to win the 1964 Italian Senior Championship through a real piece of mechanical bad luck.
Learning from experience. Mondial have now developed a new 125cc disc rotary valve racer, intended for sale to private owners if the factory gets at least 100 orders. For simplicity's sake the new model has air cooling all around and mechanical ly operated oil pump to the crankshaft, in stead of the water-cooled cylinder and hand oil pump employed in 1964. Specifi cations and features include: 55x52 bore and stroke; 14:1 compression ratio: 23 bhp at 11,500 rpm: 8-speed unit gearbox, pedal controlled from the right side; weight in running condition (fairing included) only 154 lbs.; 18" tires; battery ignition and primary drive by gears on the left.
This machine will be raced in `65 by Francesco Villa, his brother Walter, and Giuseppe Mandolini. Experiments will be carried out by these three factory riders with water cooling, horizontal or inclined cylinder position and other items, but the intended private owner machines will re main as described above.
Disc rotary valve two-stroke interest has also spread to the always-mysterious M.V. Agusta racing department. They have signed a well-known German designer, who specializes in this type of power unit, and assigned him to the preparation of a 125cc racer by the end of February. Work is progressing under the supervision of the famous factory boss, Count Domenico Agusta, but if, when and where this new mount will be seen remains a mystery. This can also be applied to the unorthodox 250cc double ohc three-cylinder racer which has been pronounced ready to race, by both Mike Hailwood and M.V. racing department chief Arturo Magni.
Another disc rotary valve lightweight two-stroke is being produced by Guazzoni, a Milan firm lately specializing in kart engines. The new model is a road going, pleasant little 50cc machine for export only. In fact, the Italian Code limits top speed of SOs to 25 mph and bhp to 1.5, while the Guazzoni reaches 68 mph and 7 bhp at 10.000 rpm. The engine is derived from the kart-type and is very sturdy: for example, gearbox/clutch assembly is the same as on the 150cc Guazzoni model, while the circular flywheel crankshaft ro tates over three big ball bearings. Signor Guazzoni states that this engine is not modified to the maximum so, relying on its sturdiness, it is possible to further increase its performance without being a highly specialized tuner, and then take part in racing. This is confirmed by the fact that in its present version the engine idles quite slowly and regularly (at about 1,400 rpm) and accelerates smartly in top gear trom 19 to 68 mph.
Other interesting features are: primary drive by chain on the right; multi-plate clutch in oil bath on the left; four-speed gearbox in unit, pedal controlled from the right; 18mm Dellorto carburetor; fully teledraulic suspension; 2.00 x 18 (front), 2.25 x 18 (rear) tires; 120 x 20mm brakes, double cradle frame.
This is indeed a machine which should please lightweight enthusiasts all over the world, and enable them to have a go at racing as well. •
