What If MV Agusta Had Not Lost Its Leadership in 1971?
What would have happened if Count Domenico Agusta hadn’t died in 1971, but had carried on vigorously directing MV’s racing? What choices were open to MV—the last significant and active four-stroke force in FIM racing—as two-strokes prepared to end MV’s long dominance of the 350 and 500 classes?
Honda addressed this same question with its 1977 announcement that it would return to 500cc GP racing—with a V-4 oval-piston four-stroke engine, its NR500 project.
MV Agusta had won 31 world championships by the end of 1970—six in 125, four in 250, seven in 350, and 14 in 500. MV’s racing may initially have been driven by a need to promote product, but the real driving force behind MV racing was Count Domenico Agusta himself. He was the driving force. His racing continued for years after the company’s income shifted in 1952 from (mostly) light single-cylinder motorbikes to helicopter production.
The MV Agusta brand of today is a new 1997 business, sharing only a name with the original company.
The Count’s role in design was like that of Louis Coatalen at Sunbeam in the 1920s: He wasn’t an engineer but knew which way the wind was blowing. MV raced two-strokes until 1950, when the Count hired Ing. Piero Remor, the man who had previously designed Gilera’s postwar four-cylinder racers. His task was to create a 125 single and 500 four to win races for MV.
Although the 1961 arrival of Honda and other Japanese manufacturers in the smaller classes pushed MV out of those results, the Italian maker dominated the 500 class. Honda became concerned when in 1965 a brilliant young rider, Giacomo Agostini, on a new MV 350 Triple took a win against Honda’s dominant 350 four. Ago’s bike had been created at the Count’s insistence, essentially a 250 twin with a cylinder added.
In the 500cc battles that ensued in 1966 and ‘67 between Agostini and Honda’s Mike Hailwood, MV and Ago prevailed overall, winning the rider’s championship in both years. Honda withdrew at the end of 1967 leaving Agostini to dominate 350 and 500 on MV Triples.
Two-Strokes Were Coming
In 1970, New Zealand privateer Ginger Molloy came second in the 500 championship—beating a field mostly made up of British four-stroke singles not manufactured since 1962. Molloy earned all his points in the series on two-strokes: a Bultaco single and an over-the-counter Kawasaki H1-R triple.
If one rider, doing all his own maintenance, could rise so high in the 500 class, what would happen when the Japanese manufacturers decided to compete in earnest?
MV Agusta’s Leader Dies
Count Agusta died of a heart attack early in 1971. Who would now direct MV’s racing? How would it cope with the two-strokes? In 1971 and ‘72 Agostini retained his 350 and 500 world titles as usual, but fast new two-strokes were close behind. Ago’s beloved Triples as mid-1960s designs, were at the end of their development. Something new was required.
As Honda did in the 1960s, MV now employed more and smaller cylinders as a means of operating at higher rpm. Under new FIM rules effective from 1968, 350 and 500 were limited to a maximum of four cylinders. The 500 triple’s bore/stroke ratio remained old-timey at 1.06. A new 500 four was designed by MV personnel—Mario Rossi and draftsman Enrico Sironi—with more recent ideas later imported by an engineer with auto racing experience—Giuseppe Bocchi. Bore and stroke of the new 500 four was set at 58 x 47mm for a bore/stroke ratio of 1.23.
This engine began life with a still-conservative valve-included angle of 45 degrees, but Bocchi modernized it in two steps: 42 and then 35 degrees. The narrower the angle, the flatter and more open the combustion chamber and, in general, the greater its potential for fast, efficient combustion with minimum heat loss.
Depending upon whose version you accept, this air/oil-cooled engine, receiving intensive development, reached 92–93 hp at 14,000 rpm, and was used by 1973 hire Phil Read to win the 500 championships of 1973 and ‘74. Others have claimed that power rose as high as 98 hp.
For 1975, Agostini went to Yamaha and took the 500 title from MV on a reed-valve two-stroke four. The MV retained a top speed advantage but the Yamaha had an edge in both acceleration and braking stability. The MV’s considerable engine-braking caused rear wheel dragging and hopping. Later, when Honda’s NR500 had these problems, they developed a slipper clutch whose grip softened when the rear wheel drove the engine during braking.
Meanwhile, Ing. Bocchi designed MV’s next 500—a liquid-cooled flat-four that began life with the bore and stroke and basic combustion chamber of the 58 x 47.2mm inline-four. It had provision for either carburetors or mechanical fuel injection. In it, narrow valve angle was fully accepted by giving it one-piece single cam covers. Although I could find no documentation of its testing, claims have been made as high as 105–106 hp. Although a chassis exists, it appears never to have been track-tested.
Why a flat-four, whose 22.25-inch (571mm) length imposes a long, slow-steering wheelbase? Experienced staff at MV knew better, but flat engines had come into vogue in F1 with claims of lowered center of gravity, lower mechanical friction, and reduced vibration.
MV won its last race in 1976, then announced its withdrawal from GP racing.
More RPMs Needed to Compete With Two-Strokes
Suzuki’s two-stroke XR14 (aka “RG500″) entered competition in 1974 at 95 hp at 11,200 rpm, rising to 100 hp a year later, then to 114 hp in 1976.
Four-stroke engines have the inherent advantage of smooth power delivery from zero throttle. But a two-stroke may not even fire at all until a certain throttle angle, when the engine begins to fire irregularly (this is why people call them “ring-dings”). Irregular firing upsets traction, so two-stroke riders postponed throttle-up until the bike was upright enough that the tire could handle the hit—even then often as a series of slip-and-grip near-highsides.
Smooth early power delivery helped Mike Hailwood on Honda’s 60–65 hp four-stroke RC166 of 1966–67 win two 250 titles from Phil Read on Yamaha’s 78 hp, two-stroke RD05 250 square-four. As long-serving GP crew chief Jeremy Burgess put it, “Which would you rather have? Earlier acceleration off each of twelve corners? Or a top speed advantage at the far end of one straightaway?”
Two-stroke cylinder-filling continued to improve during the 1980s and ‘90s, until at the end of the two-stroke era, stroke-averaged net combustion pressure rose to a value equal to or greater than that of well-developed racing four-strokes. The meaning was clear; to achieve equal power, a four-stroke now had to turn twice the rpm of the two-stroke.
Honda’s competitive experience with its NR500 four-stroke, during its 1979–81, career was that despite possibly smoother power delivery, it never won a single Grand Prix point. Its complexity was heavy and, as described by Freddie Spencer, “The engine never ‘hit’—it just revved.” At the end it was supposedly making 136 hp at 19,000. In that same year Suzuki’s 130 hp, 297-pound XR35 won the championship. What this shows is that there is a lot more to winning GP races than horsepower.
What of the Flat-Four?
Now return to MV and its 1976 situation. I suspect that had Bocchi’s prototype flat-four been track tested, it would have been found uncompetitive by reason of its long wheelbase and low engine position. When the wheelbase is too long and/or the engine is too low, weight transfer to the rear wheel during acceleration is reduced, so the tire spins rather than grips. Persuading all parties to try a “Formula One version” of the existing inline-four, in its race-proven chassis would have taken time, allowing two-stroke power to rise even further. Such a bike might have continued for a time to finish well against the new two-strokes, provided that a rider of the greatest talent could be found to ride it.
Honda had aimed its NR500 at 23,000 rpm, double what the two-stroke 500s were turning at the time. Persistent piston fatigue cracking slashed that to about 19,000.
As we know, two-stroke power continued its rise, reaching 190 in 1997, or 40 percent more than Honda got from the NR500. This suggests MV management made the right decision: to retire in dignity with 38 world championships.
We can tantalize ourselves with 4 a.m. thought experiments. What about the super-strength dispersed-phase-strengthened piston material banned in F1 in the new century? Ceramic valves? Carbon fiber connecting rods? Stop. Advanced technologies that might have helped MV or Honda four-strokes could have helped two-stroke performance just as much. When everyone switches to titanium fasteners, any advantage disappears.
And there’s this: More power could be found more quickly and cheaply in simple low-revving two-strokes than in complex four-strokes trying for double the revs.
Honda’s 1982 response was pragmatic: It wanted to win but the costly NR program hadn’t delivered. It switched to a light two-stroke triple that was basically three motocross engines on a common crankshaft. The resulting NS500 won two GPs in 1982 and made Freddie Spencer 500 world champion in 1983.
Ultimately the issue was decided administratively rather than on racetracks. Only four-strokes are eligible for today’s premier roadracing series: MotoGP.