Ducati Regolarità 125: The Skeleton in the Closet

[With Ducati recently offering up details about its production Desmo450 MX motocrosser and referring to it as “the first motocross bike from the Borgo Panigale manufacturer,” friend of MO and legendary moto-journo, Alan Cathcart reminded us that this isn’t Ducati’s first foray into off-road competition. That said, off-road racing terminology and disciplines have changed over the years. While Ducati’s claim is still arguably correct, Cathcart offers us a look into the past at the brand’s last attempt at a Single-cylinder off-road competition machine: the Regolarità 125. —Ed.]

The return of Ducati to the single-cylinder MX and Enduro market dictates a look in the rear view mirror of history to back when the famous Italian sportbike manufacturer last previously dabbled in the offroad sector. For contrary to what its PR office is stating, the new Desmo450 MX model which the German-owned Italian sportbike manufacturer bills as ‘the first motocross bike in our history’ is in fact nothing of the kind.

Lots of famous makes have skeletons in the closet, models they’d rather you didn’t know they ever made. Like the 50cc moped and 98cc scooters that MV Agusta produced back in the 1950s, or Moto Guzzi’s three-wheeled delivery truck – or indeed the smallest Norton ever sold, the overweight, unreliable Jubilee 250 twin, whose copious oil leaks stained many a British driveway. You get the picture. So how about the last-ever Ducati single-cylinder off-road bike, of which 3,846 examples were built from 1975 to 1979, which was also incidentally the first Ducati motorcycle to be built with a left-foot gearchange? It wasn’t just the fact that the 125 Regolarità and its later Six Days variant represented the Bologna factory’s only serious attempt to target the off-road market, but it was that contradiction in terms – a Ducati two-stroke!

By 1975 when the 125 Regolarità was launched in the marketplace, Ducati was now well established as the leading Italian four-stroke performance brand, with a twin-cylinder sportbike range derived from Paul Smart’s V-Twin Imola 200-winner. The idea that it should ever have tried to carve out a slice of the then-booming 125cc enduro market for sixteen-year olds peopled by 23 other makes from Ancilotti to Zündapp, via Aprilia and Beta, SWM and Sachs (whose well-regarded two-stroke single motor powered much of the competition), Montesa and Fantic, etc., seems very – well, short-sighted, let’s say.

Mind you, bureaucrats have never been much good at running bike companies, and ever since 1967 Ducati had formed part of the Italian government’s EFIM (Ente Partecipazioni e Finanziamento Industria Manifatturiera) state-owned conglomerate responsible for the day-to-day operations of the company and 114 others within Italy. However, it had the good fortune to see Fredmano Spairani appointed as its CEO in 1969, a professional manager with an open mind as well as some flair, who listened, learnt and acted on what he was told. Ducati progettista Fabio Taglioni and his colleagues convinced Spairani of the values of a product-led strategy based on the large capacity 750cc four-strokes that BSA-Triumph and Honda had just launched, underpinned by a factory race program, and that’s how the family of 750cc V-Twin Ducatis that debuted in 1971, came about.

Unfortunately for Ducati, Spairani’s success in spearheading the company’s transformation (even if production was slow to build up sufficiently to take immediate advantage of that success) meant he was appointed in 1973 to try to pull the same trick on Agusta’s aviation and motorcycle business, which had also fallen under EFIM control – and his elderly, short-sighted successor Cristiano de Eccher was only concerned with numbers, not product. So at his specific behest two new model platforms targeted at volume market segments were created that are today regarded as eminently forgettable postscripts of Ducati history – the 350/500cc parallel-twins, and the 125 Regolarità two-stroke Enduro.

Italo Forni was Italy’s star off-roader of the 1970s, a multi-time Italian MX and Enduro champion in the 125/250/500 categories, and at various times a works rider for Honda, KTM, CZ, Montesa, Kawasaki (he was the first European rider to be signed by the Japanese factory), Moto Villa (for whom he won 36 races in 38 starts in 1972) – and Ducati. Today an active 73-year old who’s enjoyed a series of key roles in the Italian bike industry since retiring from racing in 1980 while still at the top, Forni was the man Ducati engineers recruited back then to help them develop a product for a market sector they had no experience of at all, but which de Eccher had insisted must be addressed in Ducati’s catalogue – a street-legal 125cc enduro dirtbike.

“Ducati contacted me in 1973 to ask them to help develop an Enduro,” recalls Forni, “so I went to Bologna to meet Taglioni and Cosimo Calcagnile, the Commercial Manager. Taglioni had designed an all-new single-cylinder four-stroke engine to replace the wide-crankcase Mark III singles which were just then ending production, and he’d wanted to use this to develop a range of 250 and 350cc bikes for the Enduro market, to follow on from the successful Scramblers. Spairani had been favourable to this idea, but the new guy refused to consider it – he considered himself an expert on the market, and that meant it had to be a 125 two-stroke, because that was what everyone else was selling. Nevermind about Ducati’s inexperience in this sector, or the reduced profit margins in such a competitive marketplace! So Taglioni and his colleagues in the Reparto Sperimentale decided to use the bottom half of that new four-stroke engine for such a motor, but to fit it with a two-stroke top end – and since they neither knew nor cared much about two-strokes, they simply used the most successful engine in the sector as a reference, which was the Sachs. That’s why the Ducati two-stroke has the same radial cylinder head finning as the German engine, why the crankcase is so wide and heavy for a 125 two-stroke, and why the crankshaft and transmission are also over dimensioned – they were designed for a bigger four-stroke engine. People always thought this was because Ducati planned to make a future 250cc version possible – but I assure you that was never the intention!” However, de Eccher had originally intended to make a conventional 125cc road bike using the same two-stroke engine, but this idea was dropped.

Launched in April 1975, the 125 Regolarità had an air-cooled piston-port motor with ‘square’ 54 x 54 mm dimensions, originally with four transfer ports and a single exhaust in the Gilardoni cylinder’s cast-iron sleeve, then later with twin additional boost ports. Fitted with a 30mm Dell’Orto FHB carb with lift-up choke lever, and running a high 12.4:1 compression after the 10.5:1 ratio the bike was launched with had to be raised to give a much needed boost in acceleration. The engine produced 21.8 bhp at 9,000 rpm at the gearbox – comparable with the competition, but with a narrower power band compared to the pre-eminent Sachs motor it had attempted to copy, and maximum torque of just 11.8 ft-lb at 8,000 revs. The heavy duty six-speed gearbox and oil-bath clutch – remarked on by contemporary testers as “quite capable of harnessing more performance from a larger capacity engine” – were needed to coax available performance from the engine.

The 240-pound dry weight was heavy by class standards, 22 lbs more than most of its competitors, plus the fact the 125 Regolarità was homologated for a passenger was advertised by a non-streetcred strap across the 33.5-inch high dual seat, and there was a battery behind the left side numberplate to power the small headlamp with its smart but heavy steel grille (the detachable air filter was housed on the opposite side). The Motoplat CDI running 19° of ignition advance had a flywheel generator that ensured the Ducati two-stroke motor could run without the battery, meaning the exposed ignition key on the left side was only needed to turn on the lights! But it seemed strange Ducati needed to import the new bike’s ignition system all the way from Spain, rather than source the equivalent from its Ducati Elettronica sister company literally right next door in Bologna, unless it was the fact that Sachs used a Motoplat CDI, too!

The enduro Ducati’s twin-loop Verlicchi mild-steel frame was surmounted by a slab-sided six-liter plastic fuel tank filled with 5% mixture, which proved to be on the small size once magazine tests revealed a thirsty 31mpg – high for a 125 enduro. The chassis carried 35mm Marzocchi forks offering 7.1 inches of wheel travel, with the rear a box-section steel swingarm with twin Marzocchi piggyback air/oil shocks with remote air chambers running 28.4 psi of pressure, five-position spring preload adjustment, 5.1in. of wheel travel, and a choice of three upper mounting positions. But the routing of the fat Lafranconi exhaust (with a detachable rear section to allow for repacking) beneath the engine was a real handicap, says Forni.

“At the direction of the management, the first version of the bike was really more of a streetbike than a competition enduro model,” he says. “But Ducati owners love to race, even on a two-stroke, so it soon became obvious there were several changes we’d have to make to reflect this.” Yet the tiny 125mm Grimeca single leading-shoe drum brake with conical hub fitted to the 21in front wheel was definitely undersized for street use, especially with a passenger and even when its slightly larger 140mm rear companion on the 18-inch wheel was used hard – and with a class-leading top speed of 74 mph in independent tests, the 240-pound Ducati needed some stopping. However, the Akront alloy rims, Magura handlebar and levers, Aprilia switchgear and headlamp, Preston Petty flexy plastic mudguards with a small zip-up documents pouch on the rear one, Arieto numberplates and Nino Verlicchi spring-loaded footrests, were all quality components on an entry-level bike that was competitively priced versus its competitors at Lire 868,000 incl. tax ($490 in US dollars at the time, which is about $2900 today) – the Sachs-powered KTM GS125 was more than 20% more expensive, albeit 25% lighter and 10% more powerful than its Ducati rival….

In order to gain some two-stroke credibility with potential customers in a segment where up till now it hadn’t featured, Ducati supported various 125 Regolarità riders in local Italian Enduros and in France, the only other country the model was catalogued in. That extended to the 1975 ISDT in which the test bike competed, but success was slow in coming. Italo Forni was thus hired by the factory to race the Regolarità in the 1976 Italian MX and Enduro championships, as well as compete in the ISDT in Austria – in the course of which he developed an uprated version which Ducati introduced for 1977 under the Six Days label, replacing the previous model.

Boasting more aggressive off-road styling with an 8-liter aluminum fuel tank and black-painted motor, the new bike came in two versions, Cross and Regolarità, each with revised porting for the new chrome-bore cylinder and altered ignition timing, which coupled with a new design of combustion camber and piston with more squish, a larger 32mm carb, and compression raised to 14.6:1, delivered a healthy claimed power increase to 25 hp at 10,250 rpm. The weight issue was addressed via a chrome-moly frame, magnesium sliders on the Marzocchi forks, and measures such as a much-lightened steel clutch basket shot full of holes to combat the weight, down from 2.9 lbs to 2.1 lbs. Dry weight was slashed to a claimed 218 lbs, which actually turned out in magazine tests to be 229 lbs, but the front brake was increased to 140mm in size, and most important of all the exhaust was rerouted to run up and over the top of the cylinder, exiting under the seat on the left. The price was however raised to a more realistic Lit.1,271,100 (US $718) that was comparable with the competition – it’s doubtful that Ducati made much profit out of the 2,786 examples of the 125 Regolarità it made and sold in 1975-76.

“The Six Days was a much more competitive mount,” says Italo Forni. “It had an improved riding position because of a better shaped fuel tank and the tucked in exhaust. However, it was still rather fragile, and was quite highly stressed to deliver competitive performance, although by the middle of 1977, we’d begun to win races with it. But the sales had failed to meet expectations, so just as we had it coming good, EFIM decided to end the project! The original Regolarità model had lost Ducati credibility, in giving the impression it didn’t know or care about Enduros – which was indeed partly true! It was born out of a compromise, because the EFIM management wanted to have a streetbike that their 16-year old customer could ride to the café with his girlfriend sitting behind him, yet could also win races – and in the 1970s 125cc off-road sector, that didn’t happen, because there were some very specialised rival products. It was too bulky, and too heavy to ride – indeed, it was quite old-fashioned even by mid-’70s standards. It had a very peaky power delivery because to get the necessary engine performance, they had to narrow the powerband, so there wasn’t much torque, which in Enduro is a problem. It was actually better as a motocrosser, once we started removing weight, and those were the races I won on the bike before they closed everything down. Ultimately, it had everything it needed to be successful, but it just wasn’t thought through properly at the beginning – probably because Taglioni hated two-strokes, and resented being forced to produce this model, even if he did redesign the engine in 1976 to produce a smaller, lighter version. But because of the disappointing sales, the budget wasn’t there to re-tool to produce it, so it never happened. If this had powered the Regolarità from the outset, it would certainly have been more successful than it was.”

Still, that wasn’t the end of the Ducati 125 Regolarità story – for in 1979 the defunct engine project was acquired from Ducati by Leopoldo Tartarini, the owner of the Italjet factory located at San Lazzaro di Savena, on the other side of Bologna from Ducati’s Borgo Panigale base. He’d raced for Ducati as a factory rider in the 1950s, before undertaking a remarkable 13-month round-the-world trip in 1957/58 with a colleague on a pair of 175cc Ducati singles, a trip which brought the marque untold publicity that helped it stand out from its dozens of competitors just as it was getting established as a sporting brand. By the late ’70s, Tartarini's talents for building good-looking, fine-handling bikes of all capacities under the Italjet label – most notably the acclaimed Triumph Bonneville-engined 650 Grifon – were well established, leading to a close collaboration with Ducati, for which he designed all the Mark III singles, including the iconic Scrambler, as well as Taglioni's new range of 750cc V-Twins, most notably the glorious 750SS green-frame desmo Imola replica.

This close relationship, and the demise of the Enduro project, meant that Italjet was able to acquire the 125cc two-stroke engine design in all its various forms from Ducati, badged with its own name for use in various models – and doing so neatly squared the circle for company boss Leopoldo Tartarini. “I was aware of the Regolarità’s engine from its four-stroke origins,” he explained, “so I knew it had a very strong bottom end design that was capable of handling a lot more power, whether two-stroke or four-stroke in derivation, in the category I wanted Italjet to attack – this was the Trials sector, that was then gaining fast in popularity. So early in 1979 I therefore acquired all the Regolarità’s engine drawings and patterns, and modified it to produce three new engines all using the same Ducati 125cc base – a 350 two-stroke, a 250 two-stroke, and a dry sump 350 four-stroke with a single overhead camshaft that delivered 38 bhp. I used this in the Italjet Scott trials bike that debuted in 1983, of which we made about 100 examples, and Taglioni was especially pleased to see this, because it represented the form in which he had always intended the engine to appear.”

It was the end of the road for the Ducati two-stroke project – one that can only be characterised as confused, having started out as a four-stroke, entered production as a two-stroke, then given away for adoption like a problem child to a satellite company that actually did okay with it in the end. And in doing so, it actually ended up coming home – because it was Italjet boss Leopoldo Tartarini who designed the original 125 Regolarità for Ducati! “I did it over a long weekend late in 1974,” recalled Leopoldo, “and the man who helped me design it was Joe Berliner, Ducati’s American importer. At that stage there was a chance that he might import it into the USA, where the two-stroke Enduro market was now an important market sector, so he worked with me in styling it in – he was very intelligent and passionate about design, maybe surprisingly so for such a hard-headed businessman. But in the end they decided just to concentrate on the V-Twins – but we created the Regolarità together!”

But that’s not quite the end of this multi-faceted story – for as Italo Forni recounts, in 1975 he and Ducati R&D engineer Franco Farnè developed a four-stroke Enduro model for Ducati’s Spanish affiliate Mototrans, complete with disc brakes, monoshock frame, and an all-new 500cc bevel-drive SOHC engine which Taglioni had produced, using many parts and much technology from the 864cc version of the V-twin engine that was by then in production. This four-stroke Enduro was conceived one year before the XT500 Yamaha appeared which duly became the class benchmark, and was apparently a very small, light, advanced design which was not much bigger than a 125 Husqvarna. “We built two prototypes which went to Spain, but the reason it never entered production was because of Mototrans closing down,” says Forni. “This was a very good bike which pre-dated the arrival of the four-stroke Enduro boom – ironically, the EFIM guy who insisted that Ducati should build an Enduro bike got it right, but he should have let Taglioni do it the Ducati way and build a four-stroke, in which case they would have led the world!”

If only!