Motorcycle Classics

The Flying Saucer: 1954 MV Agusta 175 CSS Disco Volante

1954 MV Agusta 175 CSS
Claimed power: 14hp @ 8,500rpm (factory specs)
Top speed: 84mph
Engine: 172.3cc air-cooled SOHC single, 59.5mm x 62mm bore and stroke, 8.2:1 compression ratio
Weight (dry): 246.4lb (112kg)
Fuel capacity/MPG: 3.7gal (14ltr)/80mpg (observed)
Price then/now: $448/$10,000-$16,000

Somewhere in the world — maybe even on back roads near you — there are happy people riding in a moto giro.

A moto giro — Italian for “motorcycle tour” — often has the feeling of an Old Home Week. Many of the riders already know each other, and many first timers are friends of previous participants. But newcomers are most welcome, and as riders unload their small, usually European postwar bikes, they’re introduced around as they search for the sign-up tent.

Yet despite all the camaraderie, there is a whiff of competition in the air. A giro is supposed to be a regularity trial, not a race, but when you gather together a group of competition motorcycles, even very small and quite old competition motorcycles, the participants start to feel a need for speed.

The first Motogiro d’Italia ran in 1914. It was a real motorcycle race over Italian public roads. This counterpart of the automotive Mille Miglia became Italy’s premier two-wheel road race. After World War II the event burgeoned, and by 1954, 50 different manufacturers were competing in an eight-stage event covering more than 2,100 miles. Three years later, it was all over: A fatal crash in the 1957 Mille Miglia led the Italian government to ban public road competition.

In 2001, a company named Dream Engine, run by a Ducati executive, resurrected the giro as a reliability trial. The original giro had classes for 75cc, 100cc, 125cc and 175cc machinery. The new giro had classes for the same size bikes, with the bikes limited to 1957 or earlier. The idea caught on, and giros are now being held around the world and across the U.S., including New England, Alabama and California, in addition to the original event in Italy, which is now presented by Club Terni. The rules differ from event to event, but the idea is always the same: riding small, older bikes against the clock on scenic roads.

Many people build bikes specifically for giro events. “I first learned about giro events from a friend in Scotland, who invited me to the event there,” says Barry Porter, owner of the 1954 MV Agusta 175 CSS Disco Volante featured here. “I went over and rode and had a blast. I came back home and went looking for an MV Agusta to ride in the giro.”

MV Agusta’s early days

MV Agustas are some of the fastest, most beautiful — and rarest — giro-legal motorcycles. Like most present-day Italian motorcycle manufacturers, MV got its start after World War II. Italy was struggling to rebuild, and with much of its infrastructure in shambles people were in desperate need of cheap transportation.

At the same time, the manufacture of the military equipment that had been heavily encouraged under Mussolini’s wartime regime was banned, and companies that had been involved in war production but had escaped being bombed into oblivion found themselves in need of a complete retool. MV Agusta was one concern with an intact factory in search of a new product.

Count Giovanni Agusta started building airplanes in 1923. After he died in 1927, the Countess and their sons, Domenico, Vincenzo, Mario and Corrado, kept the company going. Domenico Agusta became interested in building motorcycles in the late Twenties, but the buildup to World War II interfered with any plans he might have had.

Italy, of course, ended up on the losing side. And while the Allied forces occupied the south of Italy, northern Italy, including the area where MV was based, was occupied by the Germans for more than a year.

At the close of the war the Agusta family still had their factory, but was forbidden to build airplanes. In the interest of keeping their workforce occupied and filling Italy’s need for transportation, Vincenzo and Domenico resurrected their motorcycle design. They secretly started on the development work during the German occupation.

Meccanica Verghera Agusta was founded on February 12, 1945. The name can be translated as the Agusta factory in the city of Verghera — although the works was established in nearby Cascina Costa, a small hamlet near Gallarate, north of Milan. Production started with a 98cc 2-stroke single. The Agusta family quickly decided to go racing, either to promote the product or because Domenico and Vincenzo had the race bug, or both.

A breathed on and massaged version of the 2-stroke, with a 3-speed transmission and telescopic forks, won its first race on Oct. 13, 1946, and went on to win a total of 41 road races and 10 offroad races. A 125cc version showed up on tracks in 1948 and, with F. Bertoni aboard, won MV’s first Grand Prix victory on Sept. 12, 1949. The Regolarita, also a 125cc 2-stroke, won a gold medal in the 1949 Welsh Six Days Trial, took the championship in the 1950 Italian Off Road competition, and in all won 11 team and 226 individual victories.

A 500cc 4-stroke developed for European Grand Prix competition debuted in the Belgian Grand Prix on July 2, 1950. Designed by Pietro Remora, this unusual looking machine sported Earles forks in front, dual shock suspension in the rear, and double overhead cams. The bialbero (Italian for “twin cam”) was the first in a line of bright red “Fire Engines of Gallarate” to clean up on tracks up through the 1960s.

The fiercely competitive nature of the Italian motorcycle market mandated that MV’s road bikes be continually improved. The first 4-stroke, a limited production 250cc tourer, appeared in 1947, with plunger rear suspension and telescopic forks. The next 4-stroke, the 1954 CST tourer, was powered by a 172.3cc single overhead cam engine that was quite advanced for its time.

Bore and stroke was 59.5 x 62mm, with a compression ratio of 6.5:1 and an 18mm Dell’Orto MA18 carburetor. As a result of the compression ratio and the tiny carburetor, it produced a mild 8 horsepower at 5,200rpm. Lubrication was wet sump, and ignition was by magneto.

The engine was a stressed member of the frame, which, outside of the engine, was a combination of steel tubes and pressed steel components, with telescopic forks, swingarm rear suspension and a choice of 17-inch or 19-inch spoked wheels.

Of course, that pretty engine cried for tuning, and it was quickly available in a speedier version. The 175 CS Sport monoalbero (single cam) was basically the same as the CST, but with a 7:1 compression ratio and a 22mm Dell’Orto carburetor. This bumped output up to 11 horsepower (some sources quote 12.5) with a top speed of 115kph, or 71mph.

Those who wanted still more performance — and could afford the 280,000 lire asking price (about $448 in 1954 dollars, when a new Harley Panhead was $761.25) — could buy a 175 CSS, or Super Sport. Compression was 8.2:1 and with a 25mm racing Dell’Orto carburetor the 175 CSS produced 14 horsepower at 8,500rpm, enabling the roughly 247-pound single-cylinder machine to fly as fast as 135kph, or 84mph. The CSS was also beautiful, and its molded, oddly shaped tank in particular caught the eye, leading enthusiasts to dub the CSS the “Disco Volante,” or Flying Saucer.

MV Agusta only made the CSS in 1954. The engine was then further uprated to 9.2:1 compression and 16 horsepower at 8,800rpm and blessed with a 5-speed transmission. This engine saw limited application in an offroad Regolarita model but was mainly used in the CSS/5v, MV’s full-tilt production road racer and nicknamed Squalo (shark) for the shark-like nose of the race fairing.

Built between 1955 and 1957, a Squalo carried Mike Hailwood to his first career wins, and a Squalo with a factory lighting kit took Italian Remo Venturi to overall victory in the last classic Motogiro d’Italia of 1957. Another Squalo followed in second. Signore Venturi, now 85 years old, is still with us, and Barry Porter had the honor of riding with him in the 2012 Motogiro d’Italia — all five days!

Barry Porter’s Disco Volante

Barry Porter’s search for a 1957 or earlier MV first led him to a CSTL, the base model of the 1954 175cc single, enhanced with a dual seat. It barely got out of its own way, but a participant in the giro he entered it in turned out to have a CSS Disco Volante for sale, complete but needing some engine work to get it running.

Now, a 1954 MV Agusta in need of engine work is a completely different animal than, say, a 1954 Harley-Davidson Panhead or a 1954 Triumph twin in need of engine work. Both the Harley and the Triumph are documented to the hilt, parts are available at swap meets or from aftermarket suppliers, and there are even workshop manuals for sale. Not so for an early MV.

The CSS MV Agusta was manufactured in small batches of up to 50 motorcycles at a time, with production starting possibly as early as 1953, and ending maybe as late as 1955. Detail changes were common between batches, and parts availability is zero. Undaunted, Barry bought the Disco and started to work on it.

It helps to have friends when you journey into the unknown, and Barry lucked into a small but stalwart group of MV Agusta aficionados. A friend joined him in having pistons made by Ross in Southern California, and Scottish friends connected him to a shop in England that specializes in upgrading MV Agusta single-cylinder bottom ends. He shipped the crankshaft over, and it was returned with a modern big-end bearing and a new crankpin to fit.

The head was rebuilt by Engine Dynamics in Petaluma, Calif. Barry installed an electronic ignition with a lighting circuit from Power Dynamo in Germany, which eliminated the need for a battery. The original Dell’Orto SS 25 semi-racing carburetor was replaced with a more tractable UB 24.

“All these upgrades were suggested by the MV Club,” Barry explains. “As I bought it, the bike was not tractable for street use. Now, it’s a good hot rod.”

Armed with his rebuilt hot rod, Barry Porter turned up for his first giro with the Disco — and blew the head gasket. “These things take time to sort out,” he says. The next year, he holed the piston. “The timing was off.” Meanwhile, Barry had been rebuilding his CSTL, so the next year he rode it, now faster and more reliable, while the CSS was in the process of being rebuilt.

Barry turned up for his fourth Giro on the freshly rebuilt Disco Volante. “I was so happy to be back on the road with my Disco. It was running well but with only a few miles to go on day one a tappet adjuster backed off, shearing the pin on the vernier adjuster for the cam.” Ouch.

“The fifth time was the charm. I had finally gotten everything just right and my result was a very successful finish. Shortly after that Giro, someone asked if I would like to put the Disco on display at the San Francisco Airport as part of an exhibit of Italian engineering. It was there nine months and I just got it back,” Barry says.

The Disco Volante is obviously a lovely bit of Italian industrial art, but it is art with a purpose: Barry Porter sees it as a platform for giro eventing.

“The best place to ride it is with other Giro-isi on other small bikes. That’s the real fun — riding with others on the same size bike. A Giro is time/speed/distance. It’s as much fun to go 45mph on these little bikes as 80mph on a big modern bike. It’s the same thrill, plus it’s great fun with the group. There you are, all tucked in for a corner, giving it all you’ve got, and you look down and you’re only doing 35mph, yet you feel like you’re flying!

“You don’t go into a turn, grab the brake and power out like on a large capacity bike. All you have is 175cc with a few horsepower and virtually no torque. You become a momentum manager. The goal is to maintain and manage speed through a corner to maximize exit speed. It’s fantastic to work on that skill. You become one with the bike,” Barry says.

And in Barry’s case, you get to become one with what has become perhaps the most iconic giro-associated motorcycle ever built. If you’ve ever considered running in a giro, maybe now’s the time.

You never know, you just might get to see Barry’s MV doing exactly what it was designed to do, running down the road with an assuredly happy rider aboard. MC

  • Published on Dec 10, 2013
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