Café Espresso: 1978-1983 Moto Morini 500

Comparing the Moto Morini 500 Sport with its primary rivals, the Moto Guzzi 500 Monza and Ducati Sport Desmo 500.

| January/February 2018

Moto Morini 500 Sport
Years produced: 1978-1983
Power: 7,500rpm (est.)
Top speed: 104mph (period test)
Engine: 479cc air-cooled OHV 72-degree V-twin
Transmission: 5-speed, chain final drive
Weight/mpg: 368lb (dry)/42-56mpg
Price then/now: $2,795/$2,500-$6,000

Samuel Dalziel Heron is hardly a household name. Yet he helped design the first successful radial airplane engines, invented the sodium-filled poppet valve (a vital component in high-power 4-stroke engines) — and lent his name to the cylinder head concept he created.

A Heron head has no combustion chamber as such: The cylinder head is flat but for the valve pockets, with the combustion chamber cast into the top of the piston. The design offered ease of manufacture, superior “swirl” (promoting more complete combustion and hence better fuel economy) while allowing higher compression ratios for more torque. Heron heads were fitted to engines as diverse as the Jaguar V-12, Ford “Super Duty” V-8, Repco-Brabham Formula 1 … and the Moto Morini 500 Sport.

Designed by Franco Lambertini and Gianni Marchesini, the 500 Sport was a development of the 1973 Morini 3-1/2 (which was intended to dodge Italy’s tax on bikes over 350cc). The 3-1/2 was an important step for the Bologna, Italy, maker, which up to then had focused on smaller sporting singles, and featured a new 72-degree V-twin engine. Essentially a bored and stroked version of the 3-1/2, the 500 was available in the U.S. in Strada and Sport versions, though the engines in both were identical.

Beneath the 500’s interchangeable cylinder heads, two bowl-in pistons ran in iron-lined alloy cylinders (also interchangeable). The pistons drove side-by-side connecting rods running on a single, plain bearing big end, while the crankshaft ran on two ball bearings. The single camshaft was driven by a toothed belt and operated the overhead valves by pushrods and rockers. Carburetion was by two 26mm Dell’Ortos and sparks by a magnetically triggered CDI from Ducati Elettrotecnica. Helical gears drove the dry clutch and 5-speed gearbox, with chain final drive. Starting was electric with kickstart backup.

The drivetrain fitted into a dual downtube steel cradle frame, with a rear swingarm controlled by two Ceriani shocks and a 35mm Marzocchi front fork. Grimeca cast alloy 18-inch wheels with triple-disc Grimeca brakes — two in the front, one at the back — were standard. In fact the roll call of components sounds like the cast of an Italian opera: Veglia instruments, Lafranconi pipes, CEV electrics, Fiamm horn, Paioli steering damper, Tomaselli clip-ons, Pirelli tires … the list goes on.

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