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Kevin Cameron has been writing about bikes for practically 50 years, first for <em>Cycle journal</em> and, since 1992, for <em>Cycle World</em>. (Robert Martin/)

What would have occurred if Rely Domenico Agusta hadn’t died in 1971, however had carried on vigorously directing MV’s racing? What selections had been open to MV—the final important and energetic four-stroke drive in FIM racing—as two-strokes ready to finish MV’s lengthy dominance of the 350 and 500 courses?

Honda addressed this similar query with its 1977 announcement that it will return to 500cc GP racing—with a V-4 oval-piston four-stroke engine, its NR500 challenge.

What would have occurred with MV Agusta if Rely Domenico Agusta had not died in 1971? (MV Agusta/)

MV Agusta had received 31 world championships by the tip of 1970—six in 125, 4 in 250, seven in 350, and 14 in 500. MV’s racing might initially have been pushed by a necessity to advertise product, however the true driving drive behind MV racing was Rely Domenico Agusta himself. He was the driving drive. His racing continued for years after the corporate’s revenue shifted in 1952 from (principally) gentle single-cylinder motorbikes to helicopter manufacturing.

The MV Agusta model of at this time is a brand new 1997 enterprise, sharing solely a reputation with the unique firm.

The Rely’s function in design was like that of Louis Coatalen at Sunbeam within the Twenties: He wasn’t an engineer however knew which method the wind was blowing. MV raced two-strokes till 1950, when the Rely employed Ing. Piero Remor, the person who had beforehand designed Gilera’s postwar four-cylinder racers. His job was to create a 125 single and 500 4 to win races for MV.

Though the 1961 arrival of Honda and different Japanese producers within the smaller courses pushed MV out of these outcomes, the Italian maker dominated the five hundred class. Honda turned involved when in 1965 an excellent younger rider, Giacomo Agostini, on a brand new MV 350 Triple took a win towards Honda’s dominant 350 4. In the past’s bike had been created on the Rely’s insistence, basically a 250 twin with a cylinder added.

Within the 500cc battles that ensued in 1966 and ‘67 between Agostini and Honda’s Mike Hailwood, MV and In the past prevailed general, profitable the rider’s championship in each years. Honda withdrew on the finish of 1967 leaving Agostini to dominate 350 and 500 on MV Triples.

Two-Strokes Had been Coming

In 1970, New Zealand privateer Ginger Molloy got here second within the 500 championship—beating a subject principally made up of British four-stroke singles not manufactured since 1962. Molloy earned all his factors within the sequence on two-strokes: a Bultaco single and an over-the-counter Kawasaki H1-R triple.

If one rider, doing all his personal upkeep, might rise so excessive within the 500 class, what would occur when the Japanese producers determined to compete in earnest?

MV Agusta’s Chief Dies

Rely Agusta died of a coronary heart assault early in 1971. Who would now direct MV’s racing? How would it not address the two-strokes? In 1971 and ‘72 Agostini retained his 350 and 500 world titles as normal, however quick new two-strokes had been shut behind. In the past’s beloved Triples as mid-Sixties designs, had been on the finish of their growth. One thing new was required.

As Honda did within the Sixties, MV now employed extra and smaller cylinders as a way of working at larger rpm. Beneath new FIM guidelines efficient from 1968, 350 and 500 had been restricted to a most of 4 cylinders. The five hundred triple’s bore/stroke ratio remained old-timey at 1.06. A brand new 500 4 was designed by MV personnel—Mario Rossi and draftsman Enrico Sironi—with newer concepts later imported by an engineer with auto racing expertise—Giuseppe Bocchi. Bore and stroke of the brand new 500 4 was set at 58 x 47mm for a bore/stroke ratio of 1.23.

This engine started life with a still-conservative valve-included angle of 45 levels, however Bocchi modernized it in two steps: 42 after which 35 levels. The narrower the angle, the flatter and extra open the combustion chamber and, typically, the larger its potential for quick, environment friendly combustion with minimal warmth loss.

Relying upon whose model you settle for, this air/oil-cooled engine, receiving intensive growth, reached 92–93 hp at 14,000 rpm, and was utilized by 1973 rent Phil Read to win the five hundred championships of 1973 and ‘74. Others have claimed that energy rose as excessive as 98 hp.

For 1975, Agostini went to Yamaha and took the five hundred title from MV on a reed-valve two-stroke 4. The MV retained a prime pace benefit however the Yamaha had an edge in each acceleration and braking stability. The MV’s appreciable engine-braking induced rear wheel dragging and hopping. Later, when Honda’s NR500 had these issues, they developed a slipper clutch whose grip softened when the rear wheel drove the engine throughout braking.

In the meantime, Ing. Bocchi designed MV’s subsequent 500—a liquid-cooled flat-four that started life with the bore and stroke and fundamental combustion chamber of the 58 x 47.2mm inline-four. It had provision for both carburetors or mechanical gasoline injection. In it, slender valve angle was absolutely accepted by giving it one-piece single cam covers. Though I might discover no documentation of its testing, claims have been made as excessive as 105–106 hp. Though a chassis exists, it seems by no means to have been track-tested.

Ing. Giuseppe Bocchi designed flat-four for MV Agusta with a claimed 106 hp. (Douglas MacRae/)

Why a flat-four, whose 22.25-inch (571mm) size imposes an extended, slow-steering wheelbase? Skilled workers at MV knew higher, however flat engines had come into vogue in F1 with claims of lowered heart of gravity, decrease mechanical friction, and decreased vibration.

MV received its final race in 1976, then introduced its withdrawal from GP racing.

Extra RPMs Wanted to Compete With Two-Strokes

Suzuki’s two-stroke XR14 (aka “RG500″) entered competitors in 1974 at 95 hp at 11,200 rpm, rising to 100 hp a yr later, then to 114 hp in 1976.

4-stroke engines have the inherent benefit of clean energy supply from zero throttle. However a two-stroke might not even fireplace in any respect till a sure throttle angle, when the engine begins to fireplace irregularly (that is why folks name them “ring-dings”). Irregular firing upsets traction, so two-stroke riders postponed throttle-up till the bike was upright sufficient that the tire might deal with the hit—even then usually as a sequence of slip-and-grip near-highsides.

Easy early energy supply helped Mike Hailwood on Honda’s 60–65 hp four-stroke RC166 of 1966–67 win two 250 titles from Phil Learn on Yamaha’s 78 hp, two-stroke RD05 250 square-four. As long-serving GP crew chief Jeremy Burgess put it, “Which might you fairly have? Earlier acceleration off every of twelve corners? Or a prime pace benefit on the far finish of 1 straightaway?”

Two-stroke cylinder-filling continued to enhance through the Nineteen Eighties and ‘90s, till on the finish of the two-stroke period, stroke-averaged web combustion stress rose to a price equal to or larger than that of well-developed racing four-strokes. The that means was clear; to realize equal energy, a four-stroke now needed to flip twice the rpm of the two-stroke.

Honda’s aggressive expertise with its NR500 four-stroke, throughout its 1979–81, profession was that regardless of probably smoother energy supply, it by no means received a single Grand Prix level. Its complexity was heavy and, as described by Freddie Spencer, “The engine by no means ‘hit’—it simply revved.” On the finish it was supposedly making 136 hp at 19,000. In that very same yr Suzuki’s 130 hp, 297-pound XR35 received the championship. What this reveals is that there’s a lot extra to profitable GP races than horsepower.

What of the Flat-4?

Now return to MV and its 1976 scenario. I think that had Bocchi’s prototype flat-four been observe examined, it will have been discovered uncompetitive by motive of its lengthy wheelbase and low engine place. When the wheelbase is simply too lengthy and/or the engine is simply too low, weight switch to the rear wheel throughout acceleration is decreased, so the tire spins fairly than grips. Persuading all events to attempt a “System One model” of the prevailing inline-four, in its race-proven chassis would have taken time, permitting two-stroke energy to rise even additional. Such a motorbike may need continued for a time to complete effectively towards the brand new two-strokes, offered {that a} rider of the best expertise might be discovered to experience it.

A top-down view of Bocchi’s flat-four. (Douglas MacRae/)

Honda had aimed its NR500 at 23,000 rpm, double what the two-stroke 500s had been turning on the time. Persistent piston fatigue cracking slashed that to about 19,000.

As we all know, two-stroke energy continued its rise, reaching 190 in 1997, or 40 p.c greater than Honda obtained from the NR500. This means MV administration made the correct determination: to retire in dignity with 38 world championships.

We are able to tantalize ourselves with 4 a.m. thought experiments. What in regards to the super-strength dispersed-phase-strengthened piston materials banned in F1 within the new century? Ceramic valves? Carbon fiber connecting rods? Cease. Superior applied sciences that may have helped MV or Honda four-strokes might have helped two-stroke efficiency simply as a lot. When everybody switches to titanium fasteners, any benefit disappears.

Would this have been a profitable chassis paired with Bocchi’s flat-four. Unlikely, however “what if…” (Douglas MacRae/)

And there’s this: Extra energy might be discovered extra rapidly and cheaply in easy low-revving two-strokes than in complicated four-strokes attempting for double the revs.

Honda’s 1982 response was pragmatic: It wished to win however the pricey NR program hadn’t delivered. It switched to a lightweight two-stroke triple that was principally three motocross engines on a typical crankshaft. The ensuing NS500 received two GPs in 1982 and made Freddie Spencer 500 world champion in 1983.

In the end the problem was determined administratively fairly than on racetracks. Solely four-strokes are eligible for at this time’s premier roadracing sequence: MotoGP.

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