Birds of a Feather: 1966 Moto Guzzi 125 ISD Trial

The beginnings of Moto Guzzi

Moto Guzzi began building motorcycles in 1921, and almost immediately started racing their products. The company had multiple Grand Prix World Championships and Isle of Man TT wins, but due to declining sales and a 1957 ban on racing on public roads in Italy, Moto Guzzi quit competing that same year. However, that was only on the tarmac. The Italian motorcycle manufacturer still contested offroad events, most notably the International Six Days Trial, or ISDT.

The ISDT was first held in 1913, in Carlisle, England. As it was originally devised, the trial was a test of both man and machine. Held on what would have been the mostly non-existent roads of the era, both rider skill and mechanical reliability played a key role in any success.

With the exception of interruptions thanks to both world wars, the ISDT ran every year after, and always in European countries. In 1973, however, the ISDT traveled to the U.S., where it was held at Ayrhill Dairy Farm in western Massachusetts. This is now the Hoellerich Farm and the location of a private enduro racing museum.

Since then, the event has been held in locations around the globe. To update the sport’s image, in 1981 the FIM changed the title to the International Six Days Enduro, or the ISDE.

Rules and regulations changed over the years, but the ISDT, and later the ISDE, remained at its core an event that sees riders complete a course of upwards of 1,250 miles in six days. Competitors must meet critical time rules, and riders are the sole custodians of their machines. At the end of each day’s competition, the motorcycles are impounded, and riders are only allowed a few moments each morning to fettle a machine. Mechanical replacement parts are extremely limited, so a competing motorcycle must be stout and sturdy in order to finish.

In 1959, at the ISDT held in Czechoslovakia, two members of the Italian Trophy team rode machines based on Moto Guzzi’s 235cc Lodola, an overhead valve single-cylinder. The ISDT Lodola’s weren’t much changed from their road-going counterparts, and they proved to be quite competitive.

Changing the lineup

The late 1950s were financially difficult times for Moto Guzzi, yet it soldiered on producing a number of motorcycles ranging from small-capacity 2-stroke models like the 98cc Zigolo to larger 4-stroke models like the 500cc Falcone.

To simplify its small-capacity offerings, in 1960 Moto Guzzi introduced the updated 110cc Zigolo and the all new commuter-friendly 125cc Stornello Turismo, or Touring. Built to a price, everything about the Stornello represented cost-savings for Moto Guzzi. The wet sump 123cc overhead valve single-cylinder engine didn’t require an external oil tank, eliminating the cost of the tank and oil lines, and the crankcase was pressure die cast, simplifying manufacture. The frame, with its dual front downtubes and swinging arm rear suspension, was adapted for production so that a single machine performed all of the welds during its construction.

By 1961, Moto Guzzi offered the Stornello in Turismo and Sport models, and continued to offer some of its 4-stroke machines for offroad work. These models were dubbed the Lodola Regolarita 175, Lodola Regolarita 250 and the Stornello Regolarita 125; regolarita is Italian for regularity, or trials.

According to Moto Guzzi enthusiast Lee Potratz of Belleville, Wisconsin, in 1963 Moto Guzzi entered the ISDT competition in Czechoslovakia with 10 motorcycles: three 250cc Lodolas, two 175cc Lodolas and five specially prepared 125cc Stornellos.

“Every rider won gold,” Lee says. “It was a banner year for Moto Guzzi at the ISDT, and it was also the last year the factory officially entered competition. Although the Moto Guzzi factory did not sponsor a team after 1963, their motorcycles were used privately through the early 1970s.”

The five Stornello Regolarita 125s used in the 1963 ISDT were factory-prepared, but they weren’t far from the specifications of the original machines. In its basic form, the 123cc Stornello models — including a factory scrambler — continued in production through to 1975, with a 160cc Stornello offered beginning in 1969. In 1970, the Stornello 160 gained an extra gear with a 5-speed transmission.

The Moto Guzzi 125 ISD Trial

And that brings us to this rare starling — the 1966 Moto Guzzi 125 ISD Trial. Lee says the machine was built for a single year only, but due to the licensing and titling process, some of the bikes are registered as 1967 or even 1968 models.

“The ISD Trial model is a replica of the bike Moto Guzzi entered in the 1963 ISDT,” Lee says. “It was a replica made by the factory for civilian purchase, and only 75 made their way to the U.S.”

According to a January 1966 announcement in the magazine American Motorcycling, 1966 marked the return of Moto Guzzi to the U.S. market. Premier Motor Corporation, a division of the Berliner group, was the sole distributor of the Moto Guzzi brand in the United States and Canada. The first machines to come over were the 123cc Stornellos, including the Sport and Scrambler. “In addition to these two models, a limited production of the I.S.D.T. Moto Guzzi, winner of 32 Gold Medals in four years running, will be offered. Prices are: 125cc Sport, $429, 125cc Scrambler, $469, 125cc I.S.D.T. Replica, $589. Prices are the same, East Coast or West Coast,” reads the American Motorcycling blurb.

Why Moto Guzzi waited some three years after the 1963 ISDT successes to offer an ISDT replica is open to speculation. It might have been at the insistence of the Berliners — the Stornello Regolarita was a formidable competitor, and it might have been thought the model could be a strong seller.

Specifications were the same across the Stornello range for 1966. The 123cc engine had a bore of 52mm and stroke of 58mm. The electrical system was 6-volt negative ground. Differences that set the limited-production ISD Trial apart from its Scrambler stablemate include a hard-chromed liner in the light alloy cylinder, which is inclined forward at 23 degrees. The engine in the replica was tuned for more power and runs an 11.4:1 compression ratio versus the standard Stornello’s 9.6:1 compression, bumping horsepower up to 13.5 from 7.

External differences include permanently affixed tommy bar extensions on both the front and rear axles. These would allow a competition rider to more easily remove a wheel for mending a flat, for example, without the need for extra tools. As well, a small chain is attached from the swingarm to the hub spacer on the left side of the rear wheel — it’s the kind of piece that could be easily lost in the dirt. The steel spokes have a larger diameter than standard and the seat is a shorter solo-style piece. A 20mm Dell’Orto carburetor was standard on the Sport and Scrambler, while a larger 22mm Dell’Orto UB 22 BS2 was used on the ISD Trial model.

Lee Potratz’s ISD Trial

A retired tool and die maker, Lee has been riding since his early 20s. His first machine was a 1974 Honda XL350, and he enjoys enduro-style motorcycles. He currently has some 15 two-wheelers, and while he says he never set out to be a collector, he’s somehow accumulated machines as diverse as BSA Victors, a Yamaha SRX250, a 1989 Honda GB500 and a 2007 Ducati GT1000.

Lee also owns this original 1966 Stornello ISD Trial. The little Moto Guzzi first belonged to Darrell Johnson of Johnson’s Cycle Repair and Accessories in Webster City, Iowa. Darrell campaigned the Moto Guzzi in 1968 at the Iowa State Enduro Championship, where he placed second.

The bike remained in Darrell’s collection until the late 1990s, when a friend of Lee’s picked it up at an Antique Motorcycle Club of America swap meet. “Darrell had retired, and was going out of business,” Lee says. “A number of his bikes and parts were offered for sale, and I was with my friend when he bought it.”

When Lee’s friend passed away some years later he willed the ISD Trial to Lee, and Lee acquired the machine in 2005. Lee’s ISD Trial is something of a time capsule, as very little has been touched on it. In fact, even the Continental “Gelande Sport” trials-type tires on the 19-inch steel rims front and rear are original. “Without a speedometer it’s impossible to verify just how far it’s gone,” Lee explains, “But there’s very little wear on anything. There’s one small tear in the seat, but that just gives the bike some patina.”

The only non-original parts on Lee’s ISD Trial are the handlebars and the grips. From the factory, the machine was fitted with a dull-chrome handlebar and red grips, but these were changed long ago at Johnson’s shop. Lee’s always looking for the correct pieces online and in person at swap meets, but he’s not holding out much hope. “It’s going to be impossible to find those,” he says.

Right now, the ISD Trial runs, and Lee enjoys showing it off at AMCA meets and other gatherings such as the annual Wisconsin Moto Guzzi Riders Rally. “Even among Moto Guzzi people, this is not a well-known machine,” Lee explains. “They know about the Roadster and the Scrambler models, but they’re not well acquainted with some of the subtle differences that make the ISD Trial its own unique model.” Of his ISD Trial, Lee says it’s a simple one or two kicks starting it from either cold or hot, and the Dell’Orto carburetor never requires flooding. The sound emitted from the high-level exhaust and muffler is, he says, “a nice crisp putt-putt-putt.

“This is one of the nicest survivor motorcycles I’ve ever seen,” Lee adds. “I’ve only had to replace the rotten fuel tank mounting rubbers, and I’ve acquired new clutch plates.” Future repair projects include replacing the clutch plates as it will lock up in low gear, and the fork seals need to be changed. After attending to those chores, Lee says he’ll continue to “keep it, take care of it and maintain it.” It might not resonate with others like Shakespeare’s plays and poetry, but of the rare starling ISD Trial model, Lee says, “I consider myself fortunate to have it in my collection.” MC