Aermacchi’s Glorious Attempt

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How about another footnote to history? This one concerns a machine called “Linto,” a 500cc Twin that was created by engineer Lino Tonti in 1967-68.

It consisted of two 250cc top ends from the Aermacchi horizontal single-pushrod DS racer, combined as a parallel-Twin on a newly designed common crankcase. A jackshaft took power from the crank to a dry clutch. The Aermacchi was known in the U.S. as “Sprint” during the time Harley and that brand were allied (1960-’78).  The 250cc Single had been developed steadily and, despite the extra moving mass of its rattling pushrods and slender and no doubt vigorously deflecting Z-shaped rocker arms, had reached 33-35 hp and an acceptable level of reliability in racing. In its early days, rider Alberto Pagani had in 1960 brought one home fifth in the Belgian GP, one place down from Mike Hailwood on the Ducati 250cc Twin. Not bad for pushrods!

The 250’s original nearly horizontal cylinder orientation (probably just enough to achieve reliable oil drainback from the head) was preserved in the Linto. At first, crankpins were arranged at 180 degrees, but vibration (a heavy side-to-side rocking motion) compelled a switch to 360. Well, why not? All those British Twins were 360s. But the difference was that the British Twins revved to 6500 rpm, but the Linto made its initial 61 hp way up at 9800. Because inertia forces increase as the square of the revs, shaking forces leapt to 227 percent of what they’d have been on an English country lane. From what I’ve been able to learn, there was trouble with primary gear failures and chassis welds breaking, and we can imagine there were also carburetion effects even with remote float bowls.

The Aermacchi Single is a case study in powerband narrowing during development, so Tonti was surely right to give his Twin six speeds.

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This engine arrived at a critical time for 500cc GP racing, when fast Nortons and G-50s—their production ended in 1962-63—were thinning out, and Giacomo Agostini on the MV Triple was winning by ever-larger margins. What was an aspiring privateer to put into the resulting vacuum? Two-strokes were coming. In 1970, crafty New Zealand privateer Ginger Molloy would come second in the 500cc championship with most of his points earned on an over-the-counter Kawasaki H1-R. No one could see the future, so at the time, a four-stroke Twin looked good, especially since it was based on available Aermacchi components. With development, Linto power rose to 65 hp at even higher revs. Hope of heaven!

Tonti and his assistant, Alcide Biotti, worked on, with financial support by ex-racer Umberto Premoli and testing by Alberto Pagani and Gilberto Milani. In 1968, Pagani’s Linto shared fourth place in the 500cc championship with Rob Fitton on a Norton Single. The following year, as the batch of eight Lintos went into service, the cheerful veteran Gyula Marsovsky put his second in the championship with 47 points to Agostini’s first-place 105. Other Lintos were sixth, 11th, 14th and 36th. The make was also second in the constructors’ championship just ahead of Norton. Linto’s best placings were several thirds during the season.

Think of the thrilling highs and dark lows, the lost sleep, the meals eaten in the shop with the smell of hot cutting oil in the air. Glorious effort, now all but forgotten.