EXTRACT FROM SLICK #8 – released in August 2020
The first Desmoquattro in the 748 IE is made on the cheap using the engine block from the old air-cooled Pantah series that equips the Ducati 750 F1 at the time. Modified to accommodate the new heat units and with the cooling system water pump mounted in the left crankcase that is driven by the timing gear reduction shaft. Bore by stroke measurements are 88x 61.5 mm for a displacement of 748.1 cc.
Heads and cylinders are aluminum, with silicon carbide particle surface coating. The heads have a central spark plug and a roofed combustion chamber to allow the Desmo’s rocker arms to work on the four valves (intake Ø 32 mm, exhaust Ø 28 mm) tilted 40° apart, driven by the two timing shafts.
Each shaft, equipped with four eccentrics working on eight rocker arms, is controlled by the usual system of pulleys and rubber toothed belts connected to a central gear shaft at the V of the cylinders, following the system invented by Taglioni in the late 1970s on the Pantah series engines and the only legacy of the recent past that Bordi and Mengoli will carry with them. The monolithic crankshaft rests on two ball bearings; the titanium connecting rods, machined from billet, are decomposable and work instead on bushings.
One of the limitations of the Pantah series crankcase is that it cannot accommodate a six-speed gearbox. An experimental unit is set up with this number of ratios-which, however, is not used on the bike that runs the 1986 Bol d’Or because it is deemed unreliable-keeping the gearbox primary and swingarm of the 750 F1 air-operated gearbox and making room for the sixth gear by moving the gearbox secondary back and reducing the wheelbase between the two shafts (from 57 to 61 mm).
The engine’s greatest innovation, however, is electronic fuel injection, a solution that was already quite common in the automotive field in the mid-1980s, but at the time still had little application in the two-wheeler industry and-especially in racing-was a first. The one on the Desmoquattro is the Weber Marelli IAW, an acronym for Weber Ignition Injection, with dual alphanumeric-type injectors. Through six sensing sensors-air temperature, coolant temperature, atmospheric pressure, engine speed, throttle valve opening, and phase sensor-an ECU controls the engine’s fueling and ignition parameters-that is, the amount of gasoline to be injected into the cylinders, the start of fuel delivery, the duration of injector opening, and ignition advance-using its mappings or EPROMs (Erasable, Programmable, Reading, Only, Memory) .
Normal administration on modern-day engines, but absolute science fiction in 1986! In fact, fine-tuning the system would be long and laborious and would occupy Ducati engineers and Marelli until all of 1988.
The adventure of the 748 IE at the 1986 Bol d’Or – entrusted to Virginio Ferrari, Juan Garriga and Marco Lucchinelli – ended at six o’clock in the morning due to the breakage of a connecting rod pin when it was in seventh position, but it made Ducati realize that the right way to go was the one indicated by Bordi and Mengoli.
Between October 1986 and February 1987, a new engine, with a wider crankcase to accommodate the six-speed gearbox discarded at the Bol d’Or and displacement increased to 851 cc thanks to an increase in bore (from 88 to 92 mm) and stroke (from 61.5 to 64 mm), was built and mounted on the first 851 that would win the Daytona “Battle of the Twins” with Lucchinelli in March 1987.
The thermals of the new engine are very similar to those of its predecessor, as are the timing components. Light alloy heads house valves made of Nymonic-a special alloy of nickel, chromium, and aluminum that is low viscous creep and resistant to corrosion at high temperatures-. which work in cobalt-bearing austenitic steel seats, maintaining the same diameter as those used on the 748 IE. The cylinders have Cermetal-treated liners (an anti-wear treatment Ducati had a Tuscan company called Tecnol perform), while the pistons, with a polished top and three segments, two seals and one oil scraper, have a friction-treated shroud and are lighter than their predecessors. The monolithic crankshaft is made of nitrided steel. The connecting rod pin is 42 mm in diameter, and the main journals are 35 mm. In 1987, billet, decomposable titanium connecting rods were used, working on bushings at both the foot and the head, with a wheelbase of 124 mm and a length of 142 mm.
The twin-cylinder 748 IE of 1986 had almost 93 hp, while the first Desmoquattro 851 soon reached 115 hp, and during 1987-a year of experimentation and testing in preparation for engagement in the fledgling World Superbike Championship-as many as 120 could be seen on the dyno. After the Daytona triumphs that season, the 851 raced with Lucchinelli in the “Superbike Trophy,” the forerunner of the Italian SBK championship, losing it to Fabrizio Pirovano due to the vagaries of electronic injection – which on several occasions left the former 500 world champion stranded – and overly delicate packing.
Ducati’s run-up to the first Superbike World Championship title in its history begins with this 851, with which Marco Lucchinelli in 1988 participated in the first edition of the SBK World Championship. The bike is still a prototype, and at the time of Lucky’s historic victory at Donington Park, not even all 500 examples required to have homologation to race had been built, but only a batch of seven pre-series bikes and an unspecified number of 851s already “kitted” track-ready.
But both the promoter Sports Marketing and the FIM turn a blind eye because the official presence of the Italian manufacturer lends luster to a World Championship that is taking its first steps and from the regulatory point of view still has many gaps.
Ducati’s opponents, on the other hand, are less permissive than the Federation. They would like his ouster from the championship and are appeased only when they realize that Lucchinelli does not pose a serious threat because the 851 has reliability problems. Over the course of the season, he will win only one other race-the first round of the Austrian GP at Zeltweg-forgoing the expensive double trip to Australia and New Zealand that closes the World Championship.
1989 is a pivotal year. Marco Lucchinelli, having hung up his helmet, becomes the team manager of the team. Which at the second edition of the Superbike World Championship enters two riders: the young Baldassarre Monti, thrown into the fray after winning the Italian Supertwin and the experienced Raymond Roche, who instead comes from the World 500.
The bike is completely revised. Engineer Bordi, taking advantage of the technical regulations that allow this change, increases the Desmoquattro’s displacement again. The first step brings it to 888 cc (bore per stroke of 94×64 mm, instead of 92×64 mm) and is the version used by Roche and Monti for most of 1989. The second step, on the other hand, used exclusively by Roche in the last GPs of the season, raises the displacement to 916 cc (bore per stroke 95.6×64 mm) thanks to a new re-bore of the cylinders up to the maximum limit allowed by the castings.
The engine is then revised in all those details that had given it reliability problems in 1987-88: stronger packing, revised cooling system, new timing, and increased compression ratio.
At the chassis level, the old chromium-molybdenum steel tube trellis frame that has accompanied the 851 since its beginnings, built by Verlicchi and inspired in geometry by the old Pantah F1 family of the mid-1980s, gives way to a revised structure better suited to ever-increasing power. The chromium molybdenum steel (25Cr-Mo4) trellis has perimeter tubes with a diameter of 25 mm and a thickness of 1.5 mm, while those of the seatpost frame (bolted to the rest of the structure) together with the tubes of the triangulation inside the trellis are instead 22 mm and maintain the same thickness. The inclination of the steering head, on the other hand, increases from the 27.5° of the 1987-1988 frame to 25°, with a reduction in the trail from 125 mm to 95 mm and a consequent decrease in the bike’s wheelbase to 1,430 mm.
Suspension is Ohlins rather than Marzocchi, with a 41.7-mm upside-down fork at the front; at the rear, however, a single shock absorber adjustable in spring preload and compression works with a rectangular-section light alloy swingarm lacking lower triangular reinforcement.
The brakes are Brembo Serie Oro, with 320 mm (front) and 260 mm (rear) discs with four- and two-piston calipers, respectively, but during the course of the season they are tested-and then discarded. also four-piston Lockheed calipers, like those used at the time in the 500 GP World Championship. Power is not stated, but it is higher than the 120-125 hp of 1987-1988, while running weight drops to 158 kg.
Roche in the debut race at Donington had impressed everyone by scoring pole position and fastest lap with the 851 (the initials, despite the increase in displacement, remained the same) before being forced to retire due to electrical problems. Reliability continued to be the Achilles heel of the Italian twin-cylinder still throughout 1989. Roche wins for the first time at Brainerd and then repeats in Germany, at Hockenheim, and at Pergusa, in the first World SBK GP held in Italy, winning more heats than anyone else (five, compared to three for World Champion Fred Merkel and four for runner-up Stephane Mertens), but he is third in the World Championship due to seven retirements out of a total of twenty-two heats. Monti, on the other hand – eighth in the World Championship – won the Italian Superbike title.
With the experimental 916 engine Roche finished with a fourth and a second place at the Australian GP without reaping much benefit in terms of lap times with this “big bore” version. The subsequent double retirement at Manfeild, New Zealand, thus prompted Bordi not to continue on this path and to concentrate, ahead of the new season, on the 888 cc engine.
The 1990 bike is not much different from the one that raced the previous year. Roche and newly acquired Falappa-who received the new 851 only on the eve of the first GP at Jerez de la Frontera-confirmed this after the first contact in Spain. Identical chassis apart from a new swingarm with a reinforced lower truss and modified suspension linkage. The Desmoquattro, on the other hand, has been revised by Bordi in terms of heads and camshafts to have more mid-range pull. The new crankshaft has stronger packing pins and lightened flywheels, lightened and rebalanced crankshaft, special alloy pistons. The ignition pickups-which went into the dock for the 1989 recalls-are replaced and the cooling system improved.
The 1990 851 has about 130-134 hp at 11,000 rpm. At the beginning of the season it weighed 154 kg in running order (with all fluids, but no gasoline), and the work of the Racing Department focused on improving the power-to-weight ratio by trying to lighten it to the minimum weight allowed by the regulations for twin-cylinders (i.e., 140 kg) without further work on the engine.
By using carbon and Kevlar for the fairing, tail and fender, fitting a new exhaust with carbon-fiber tailpipes, lighter wheels and a smaller curved radiator, the 851’s weight drops, at the Italian GP in Monza, by about ten pounds.
Weight and power (140 hp and 143 kg, respectively) would change in 1991 with the new version taking the name 888-as the engine displacement-and being entrusted to three teams: the in-house one with the confirmed Roche and Falappa and with Lucchinelli directing operations, the one managed by Eraldo Ferracci that fields the American Doug Polen and relies on the technical collaboration of Nepoti and Caracchi’s NCR, and finally the family-run one of Stephane Mertens-with his father acting as team manager-who leaves the Honda with which he raced two seasons to embrace the cause of the Borgo Panigale manufacturer.
In 1991 the 888 dominated Superbike to the tune of records, winning both the World Drivers’ Championship with Polen and the Constructors’ World Championship, and finally also won the European Championship (held concurrently with the World Championship) with Davide Tardozzi. But that of the 888 is another chapter in Ducati’s sporting saga. A parallel chapter to that of another fundamental model in the history of the Italian company, which began to take shape even on the eve of Raymond Roche’s 1990 triumph.
In fact, on the occasion of Giancarlo Falappa’s first test with the 851 (still in the old version) conducted at Misano on a cold January day, the journalists present are told that Massimo Tamburini is completing a new motorcycle, again with a chromium-molybdenum steel tube trellis frame-but completely redesigned equipped with technical solutions never before seen by Ducati, such as a single-sided rear swingarm. This new model will use the oversized 916 cc version of the Desmoquattro and possibly compete in some endurance races, such as the Suzuka Eight Hours and the Bol d’Or, before applying for homologation to run in the 1991 World Superbike Championship.
The bike referred to is, of course, the 916, which, however, would have a much longer gestation than expected and would only land in World Superbike in 1994 to bring the world title back to Borgo Panigale, after the previous year’s American Doug Polen with the Kawasaki ZXR 750, had broken Ducati’s positive streak begun by Roche in 1990.
CONTINUED ON SLICK #8