As the technological high points of 1920s motorcycle racing began to look – and perform – like the antiques they’d become by the 1930s, the fratelli (brothers) Benelli took stock of the obvious trends of Grand Prix racing. The future of racing was clearly headed towards extracting more power from multi-cylinder, supercharged engines.  Moto GuzziGileraBMW, DKWNSU, and even AJS and Velocette in England were racing or developing such engines by 1938.  As champions in the 250cc racing class, Benelli set about that year designing a new 250cc racer, with four cylinders, twin overhead camshafts, a supercharger, and watercooling.  Trends in chassis development were also attended, and as sketched, the new machine would retain the hydraulic-damped girder forks and rear swingarm suspension of their singles, plus large-diameter alloy brakes to manage the inevitable blistering speeds to come from such an engine, given Benelli’s expertise with tuning small engines, especially in cam design, intake porting, and carburation.

The original Benelli four-cylinder DOHC racer of 1939-41, with integral supercharger and a 146mph top speed. [The Motor Cycle]
The gem of an engine designed by Giovanni Benelli produced in 1939 had a short stroke (42mm stroke x 45mm bore), with 12:1 compression pistons, and spun to 10,000rpm, which was astronomical at that date. At peak revs the motor cranked out 52.5hp, good enough for 146mph on test runs – the fastest 250cc racer by a long shot, and fully 16mph faster than their nearest rival, the brilliant supercharged 250cc flat-single from Moto Guzzi.  With such devastating performance (exceeding by 20mph the factory 500s of Norton and Velocette!), Benelli were confident of another European Championship, but the little ‘four’ wasn’t ready for the 1939 racing season.  By the time the ‘engine bugs’ were sorted, it was 1940, and the competition was no longer playing nice.

The original 1940 Benelli 250-4 still exists today. [The Vintagent Archive]
Lacking martial confidence in their native Italy, Benelli race chief Vincenzo Clementi stashed the entire racing fleet in rural areas away from their industrial base in Pesaro.  It was rumored their precious new 250cc ‘four’ engine was hidden at the bottom of a dry well, while the chassis slept under a haystack, inside a barn. Their decision proved wise, as during 1940 and ’41, Pesaro was bombed heavily; the Benelli factory had been converted to aero engine production (Daimler-Benz and Alfa Romeo designs), and when the Allies advanced northward in Italy, all the precision machine tools were moved by the German army to more secure territory inside Austria and Germany.

An exploded view of the 1960 Benelli four-cylinder motor, with gear-driven DOHC and no blower…and 16hp less than the pre-war motor! [Motorcycle Sport]
When the company returned to single-cylinder racers postwar (netting them a World Championship in 1950), by 1960 Benelli’s line of small-capacity motorcycles was selling very well, even in the USA through the department store Montgomery Wards.  With profits in hand, funds were allocated for the design of a new four-cylinder Grand Prix racer. Race chief Ing. Savelli and Giovanni Benelli designed an entirely new engine which bore resemblance to the 1938 design, but in truth, by 1960 a DOHC four with gear-driven cams had become the accepted pattern for a racing engine, having been developed by Gilera (from the original CNA/Rondine ‘fours’ dating back to 1926!), copied by MV Agusta, and then again by Honda, who won the 250cc World Championship title in 1961.

The complete 1960 Benelli four-cylinder 250cc GP racer, on its press lauch. [Hockenheim Museum Archive]
The new Benelli four used an even shorter stroke than the pre-war motor (40.6mm stroke x 44mm bore), a 6-speed gearbox, weighed only 264lbs, and gave 40hp at 13,000rpm (oh, how supercharging was missed!  This was 12.6hp less than the blown 1939 design).  The completed machine was revealed with great publicity in June of 1960, but wasn’t ready to race until 1962, and Silvio Grassetti had only one ‘win’ that year, at Cesenatico, but it sounded a bell at Honda, as both Jim Redman and Tom Phillis were bested on their Factory Honda 4s.  MV had withdrawn from the 250cc class the year before, to concentrate on retaining their 350cc and 500cc GP dominance.

Tarquinio Provini on the 250cc Benelli 4 in 1965; note the 7″ dual disc brakes. These are American Airheart brakes from Go-Kart racers, and were possibly a first in GP racing, but proved inadequate on at 143mph, especially in the wet. While the concept was sound, the brake pads hadn’t yet evolved for serious high-speed use. Benelli used them only in ’65, retreating to reliable racing drums… [Motorcycle Sport]
Tarquinio Provini, a veteran racing star with two World Championships, joined Benelli in 1963 to develop and race the new four. He shortly increased power to 52hp at 16,000rpm, with a 7-speed gearbox, and 141mph top speed. A new frame lowered the center of gravity and pared weight down to 247lbs. Years of ignition troubles with the high-revving engine were finally cured by fitting an American racing magneto…from a Mercury two-stroke boat engine. Provini won every race in the Italian championship in ’64, and the Benelli shocked the world by out-running the Japanese opposition at the super-fast Monza GP in 1965.

Tarqunio Provini hard at it in 1966. [Motorcycle Sport]
By ’66, the Four had 8 gears, and a larger version with 322cc was introduced to compete in the 350cc GP events, going head to head with the ‘big boys’, MV Agusta, Honda, and Yamaha. Provini had a bad crash at the Isle of Man TT that year, and injured his spine enough to retire from racing. Benelli had never fielded a ‘team’ of professional riders who came and went with lucrative contacts; the family business had close bonds with the one or two racers they supported, and Provini’s injury took the steam out of Benelli’s race department for over a year.

The immortal ‘Paso’, Renzo Pasolini, in 1968. [Motorcycle Sport]
Benelli re-entered the racing fray with rider Renzo Pasolini, who won second place in both the 350cc and 250cc classes at the 1968 Isle of Man TTs, and dominated the Italian Championship in both classes the rest of ’68, giving Giacomo Agostini and his MV and excellent view of the Benelli’s tailpipes all year long. In 1969, Kel Carruthers joined Pasolini, and the pair made an unbeatable team, each winning three GP victories that year, giving Benelli their second World Championship title.

Renzo Pasolini leaping Ballagh Bridge at the 1968 Isle of Man TT, which he won. [Hockenheim Museum Archive]
Kel Carruthers joined Yamaha in 1970, but Pasolini took third place in the World Championship that year. That year the Benelli family sold the factory and name to Alejandro de Tomaso, more famous for his automotive exploits than two-wheeled savvy, and support for developing the racers waned. Still, Jarno Saarinen was hired in ’72, and won his début races at Pesaro in both 350cc and 500cc classes.

Renzo Pasolini with Kel Carruthers in 1968. [Motorcycle Sport]
Both Saarinen and Pasolini left Benelli for ’73 (for Yamaha and H-D, respectively), and Walter Villa became Benelli’s top rider. With horrific irony, Villa’s 350cc Benelli was blamed for leaving a trail of oil during his race at Monza, which was then not cleaned up for the 250cc race, in which a multi-machine crash killed both Saarinen and Pasolini. The details of the accident have been debated ever since, although it seems a catastrophic seizure of Saarinen’s Yamaha (not an uncommon occurrence) may have led to the chain-reaction melée.

Kel Carruthers at the 1970 Isle of Man TT. [Motorcycle Sport]
Benellis interest in racing plummeted when new FIM rules limited 250cc racers to two cylinders and six speeds, which guaranteed an unstoppable rise of two-stroke racers, as their double-time combustion could only be opposed by outrageously sophisticated four-stroke engines, such as the Honda 6-cylinder… and a secret Benelli 250cc V-8 which was under development.  That would certainly have put Benelli on par with Moto Guzzi as masterful creators of racing exotica. The FIM, in their wisdom, preferred the crackle of two-strokes to a technical war of miniaturized-miracle racers, a decision that eventually killed Grand Prix motorcycle racing entirely, and led to the birth of MotoGP.  But that’s another story.

Jarno Saarinen…with his wife Soeli famously giving pit signals in her bikini. It was certainly hot in Italy… [Motorcycle Sport]
Related Posts

The Vintagent Classics: Kid Speed

Two auto racers compete for the same…

The Vintagent Trailers: Dream Racer

Dream Racer is an inspiring account of…

DG Manktelow, Cafe Racer

As a college student, DG Manktelow…

Subscribe to Our Weekly Newsletter