Little Speed Fiend: 1967 Ducati 50 SL/1

Small and perfectly formed, the little-known Ducati 50 SL/1 is a 2-stroke and the stuff of teenage dreams.

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by Phil Aynsley

1967 Ducati 50 SL/1

Engine: 49.66cc air-cooled 2-stroke single, 38.8mm x 42mm bore and stroke, 11:1 compression ratio, 6hp @ 6,500rpm
Top speed: 60mph-plus
Carburetion: Single, remote-float, 18mm Dell’Orto
Transmission: 4-speed, chain final drive
Electrics: Magneto ignition
Frame/wheelbase: Dual downtube steel cradle frame/45.3in (1,150mm)
Suspension: Telescopic fork front, dual shocks rear
Brakes: 4.65in (118mm) SLS drums front and rear
Tires: 2.25 x 19in front and rear
Weight (dry): 130lb (59kg)
Seat height: 28.7in (730mm)

Ducati isn’t readily associated with 2-stroke motorcycles, but they formed an important part of the company’s marketing strategy in the early 1960s.

Aimed at a new youth market, some knowledgeable fans of Ducati’s history consider the unusual 50 SL/1 of 1967 one of the most beautiful models it ever made.

The ultimate development of a lightweight range first launched in 1961 with the Brisk and Piuma mopeds, the SL/1 took Italy’s crowded micro-motorcycle market to a new level of styling and performance.

The tiny 50 SL/1 featured some significant design elements that would later appear on its much larger 4-stroke singles. Chief among these were the distinctive twin filler caps on the gas tank. Those dual bayonet-style levers became a signature for Ducati’s 1968 “wide case” Mark 3 singles.

Those bigger models launched Ducati into the “desmo” era that survives today, showcased in MotoGP and World Superbikes.

But a year before Ducati’s desmo singles arrived, the SL/1 had serious road presence. That long, sculptured, silver-and-red gas tank screamed racetrack technology, and so did the solo seat and racing handlebars.

These details underlined the fact the tiny engine had been significantly boosted in power to achieve a top speed of over 60mph.

The stuff of dreams

A teenage dream machine, the 50 SL/1 was a long way from Ducati’s original mopeds, which were designed to be practical and affordable, and to attract younger riders to boost Italian domestic sales. Because it was never exported officially outside Europe, the 50 SL/1 remains a very rare motorcycle in the U.S.

This example is owned by Peter Calles, whom we featured in a recent issue (see Full House). It is a perfect bookend to his collection of Ducatis that spans several decades and cubic capacities.

The fact that it is in completely original and unrestored condition makes it a genuine time capsule.

Not the only pocket rocket

Ducati’s 50 SL/1 may have been a leader in ultra-lightweight café racers but it had many challengers (see sidebar). These micro-motorcycles were relatively cheap to manufacture. Companies that didn’t have suitable engines simply bought one in from another manufacturer, such as from Minarelli and Morini in Italy, or Zündapp in Germany.

The market segment was fueled by the first generation born after the end of World War II. Young students and city workers commuting to their first jobs were looking for affordable options, so these 50cc motorcycles and mopeds had to be cheap to buy and run: 2-stroke engines fit the bill perfectly and the price in most cases was half that of the smallest 2-stroke model available.

Safety laws introduced in Italy in 1959 limited mopeds to 40kmh (roughly 25mph), so typical engine outputs were limited to around 1.6 horsepower. This took the pressure off manufacturers to develop ever more powerful models. In theory they could keep churning out the same model year after year with cosmetic upgrades.

However in typical Italian motorcycle engineering tradition, it wasn’t long before performance specialists had managed to unshackle stifled performance. The race was on for the hottest pocket rocket of the Sixties.

Hunting for a new market

Ducati began with several 48cc models launched in 1961 with 48cc engines. Among the range were names like Cadet and Cacciatore (a dual-sport model with its title translated as “hunter”).

A year later the Piuma Sport brought a hint of performance to Ducati’s sub-50cc range. It featured more motorcycle-like styling and a more powerful engine. Although shackled in the Italian market at 1.5 horsepower, the 108-pound roadster could be derestricted in some other European markets to reveal a more than credible 4.2 horsepower and 50mph top speed.

The 48 SL came along in 1964, again intended only for the Italian market. Improvements included wheels and brakes from a larger model in Ducati’s range. The 2-stroke engine was slowly upgraded. Eventually it became fan-cooled with a large aluminium shroud covering the barrel and head. However, it still featured the much criticized and awkward 3-speed gearbox controlled through a twistgrip on the left handlebar.

Late 1966 saw a mini-upheaval in the range as Ducati thoroughly revised the 48 SL to come up with the 50 SL (standard model), followed a few months later in 1967 by the 50 SL/1 hot rod version.

Both models had a freshly designed, 50cc 2-stroke engine that dispensed with the fan cooling. A 4-speed gearbox brought the model into the modern age, as did the café racer styling of the SL/1.

A higher compression ratio on the SL/1 along with sports porting, an alloy barrel and 18mm Dell’Orto carburetor (as large as any fitted to Ducati’s 250/350 4-stroke singles) made 6 horsepower. They were available with high or low-level exhaust systems.

The SL/1 was a revelation and had so much potential for even more tuning that some buyers quickly converted them to dedicated racers and entered Italy’s national 50cc class. But glory was short-lived. The SL was discontinued while various versions of the SL/1 appeared through until the end of 1968. A final model, called the SL/1A, reverted to conventional roadster styling.

By now Ducati’s efforts were focused on its larger 4-stroke wide case desmo singles. These were forming the basis of a whole new family of models, including the Scrambler and Mark 3 D 450, which quickly achieved strong sales in export markets, including the U.S. Ducati’s 2-stroke micro-motorcycles had been overtaken by a new era.

To restore or not?

Why not restore this American-owned example of Ducati’s ultimate micro-motorcycle? Simple. It is an excellent guide for other people’s restorations, right down to the Ducati-logoed tire pump mounted on the swingarm. The location of its model-identifying decals and myriad other details can easily get lost when a motorcycle is disassembled. This 1967 50 SL/1, with its gentle patina of low use, is probably worth more unrestored. MC

Rival 50’s from other companies

Early-1960s Atala Golden Arrow

Atala produced a range of 2-strokes from 49cc up to 125cc, usually powered by Minarelli engines. This early-1960s Freccia D’oro (Golden Arrow) uses a 49cc type P-3 Minarelli engine. Note the unusual, twistgrip-mounted, cable-operated gear-change mechanism similar to Ducati’s.

1965 Giulietta Super Sport

Giulietta was a division of the Peripoli motorcycle company, which started making motorcycles in the late 1950s. By 1965 it was the seventh largest manufacturer in Italy and production continued into the 1980s. This unrestored 1965 Super Sport 50cc was last registered (in Italy) in 1974.

1966 Mondial Record Special

F.B. Mondial brought the passion of its much larger 4-stroke racing motorcycles to the street with its 48cc 2-stroke Record Special. This exquisite and rare 1966 model has had minimal use since new and is 100 percent original and unrestored.

1966 Garelli Monza Junior

Twenty-two-year-old Adalberto Garelli founded his factory in 1919 with the first Garelli motorcycle using his own 350cc 2-stroke engine. It set a long-distance record from Milan to Naples, proving 2-strokes were durable. This is an unrestored, 5hp, 1966 50cc Monza Junior.

1970s Negrini

Negrini, founded in 1954, offered a varied range of small capacity mopeds and motorcycles before its Modena factory closed in 1972. This early 1970s 50cc model is powered by a Franco-Morini engine.

1972 Malanca Testarossa

Malanca, a specialist in 50cc models, was established by Mario Malanca in Bologna in 1956. From 1968 it also produced race versions that took Walter Villa and Othello Buscherini to six Italian Championships. This restored 1972 50cc Testarossa has a four-speed gearbox and a top speed of around 90kmh (56mph).

1972 Cimatti S5

Cimatti, started in Bologna in 1949, produced mopeds and small capacity motorcycles until 1984. This unrestored 1972 50cc Cimatti S5 has all the café race kudos of a much larger motorcycle. The only unoriginal parts are the header/muffler (from the earlier S4), which runs on the incorrect side for this model.

1975 Malaguti Olympique V5

Malaguti is one of the very few original Italian motorcycle/scooter firms to survive in family ownership. Since the 1970s Malaguti’s large range of small capacity motorcycles and scooters has made it Italy’s third largest manufacturer. This 1975 50cc Olympique V5 is powered by a Franco Morini engine and has a 5-speed gearbox.

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