Café Espresso: 1978-1983 Moto Morini 500

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.

Patriotism aside, Morini could have chosen better. Period testers complained of awkward switchgear, a wildly gyrating tachometer needle, an overly optimistic speedometer and electrical gremlins. Another significant beef: the Sport’s ergonomics, with the seat too low and thinly padded, pegs too high and too far forward, and bars too far away, forcing riders into a cramped crouch. Other niggles included reluctant starting, a grabby clutch and vague shifting (the 3-1/2 was designed with a right-side shifter, but the 500 Sport was given a complex crossover to meet DOT left-foot shift requirements). It also lacked a proper oil filter, and required a seven-step procedure to access the air filter. Nor was it as fast as its Japanese competition, turning the standing quarter in 15.4 seconds at 84mph. By comparison, the 1978 Yamaha XS500 turned the quarter-mile in 14.57 seconds. It was a lot more expensive, too, with an MSRP of $2,795 in 1978 compared to the XS500’s $1,589.

“To be justifiable, the Sport needs one great redeeming virtue. The Morini does have one long suit, and it’s the classic Italian forte: handling,” noted Cycle in 1979. “Initiating turns … is a delight on the Morini, with the rider in absolute command at all times. There is none of the high-strung nervousness associated with the Yamaha RDs, just responsive, precise steering.” “The excellence of the Morini’s handling is almost shocking,” Rider wrote. “Such sensitivity of control is not to be found on mass-produced motorcycles.”

“The Morini, then, is not made with the average buyer in mind,” concluded Cycle. “The Sport was made for the hard-core Italophile … looking for a smaller Italian Flashbike. And if he buys a Moto Morini, he’s found it.” MC

Contenders to Moto Morini’s 500 Sport

1980-1983 Moto Guzzi 500 Monza

Years produced: 1980-1983
Power: 48hp @ 7,500rpm/109mph (est.)
Engine: 490cc air-cooled OHV 90-degree V-twin
Transmission: 5-speed, shaft final drive
Weight/MPG: 353lb (dry)/45-55mpg
Price then/now: $3,249 (1981)/$1,500-$4,800

After taking over Moto Guzzi in 1973, Alejandro de Tomaso commissioned Lino Tonti to design a new half-liter bike to take on the Asian imports. Tonti downsized the classic Guzzi shaft-drive V-twin, but with numerous design and cost-saving improvements. The 90-degree twin used Heron cylinder heads fed by 24mm Dell’Ortos. Drive to the rear wheel was via a dry, single-plate diaphragm-spring clutch and 5-speed gearbox with shaft final drive. The engine unit bolted to a dual downtube cradle frame with removable lower rails. Features of the 500 included Guzzi’s linked braking system with three Brembo discs, an easily accessed oil filter and a redesigned swingarm/driveshaft pivoting in the gearbox.

The Monza version, launched in 1980, used 28mm Dell’Ortos, bigger valves, Nikasil-plated cylinders (instead of steel liners) and contact-breaker points replaced the problematic Bosch electronics. Its sportier ergonomics and a small fairing made it less comfortable in town, but worked well on the open road. Reviewers praised the Guzzi’s handling, suspension and brakes, all of which were considered vastly better than the Japanese competition. “The Guzzi tracks through corners as if it were laser-guided,” Cycle said. They also liked its robust drivetrain, but experienced problems with suspect switchgear. And, like Morini’s 500 Sport, the Monza was too rich — about 60 percent pricier than its Asian rivals.

1977-1983 Ducati Sport Desmo 500

Years produced: 1977-1983
Power: 50hp @ 8,500rpm/115mph (est.)
Engine: 497cc air-cooled SOHC desmodromic valve parallel twin
Transmission: 5-speed, chain final drive
Weight/MPG: 407lb (dry)/50mpg (est.)
Price then/now: NA/$1,100-$3,800

In response to a request from U.S. importer Berliner Corp. for a half-liter bike, Ducati produced the stodgy 1975 500 GTL, having passed over Ducati engineer Fabio Taglioni’s new L-twin design. With limp performance and controversial styling by Georgetto Giugiaro, it was a sales disaster. And though he’d sworn to have nothing to do with the parallel twin, Taglioni was persuaded to breathe his magic on the engine. Italjet’s Leopoldo Tartarini was also hired to glam up the bike.

Taglioni added desmodromic valve gear and boosted output to 50 horsepower with 30mm Dell’Ortos and higher compression. Tartarini specified a sturdier dual downtube frame, FPS alloy wheels, Paioli fork, Marzocchi rear shocks and triple-disc Brembo brakes. The resulting 1977 500 Sport Desmo had good power, steady handling and excellent brakes, but the Sport needed lots of revs to make its power, which produced copious vibration and exposed bottom-end weakness. Making things worse, the generally sad state of the government-owned Ducati factory showed up in awful build quality. By 1979, Dr. T’s 500 Pantah L-twin was on sale. It was lighter, smoother, more reliable and showed Ducati’s way forward. Just 50 or so Sport Desmos are thought to have been sold in the U.S., making it a rare — but not necessarily desirable — model.