Tag Archives: Takazumi Katayama

The Yamaha YSK3 “Sankito”

 

When is a factory racer not a factory racer? The enigma of the “Sankito”.

The ascendency of the Japanese factories in Grand Prix motorcycle racing during the 1960’s brought with it a technical revolution that escalated at a breathtaking pace. The battle for supremacy in the different capacity classes between the advanced two-stroke racers from Yamaha and Suzuki to take on the might of the multi-cylinder four-stroke Honda’s forced the governing body of Grand Prix racing, the Federation Internationale de Motocyclisme, to act. 1969 saw new regulations that placed a restriction on the number of cylinders and gearbox ratio’s allowed as well as a new minimum weight for the different capacity classes. The aim was to allow European manufacturers to remain competitive by reducing the cost of developing new Grand Prix machinery.

Unfortunately, it saw an exodus by the Japanese works teams from the World Championships heralding in a new decade of the privateer, with Yamaha and Suzuki providing reasonably priced production racers to individuals and dealer teams, while their European importers received the latest factory versions. To a certain extent, it levelled the Grand Prix racing playing field; a good privateer could develop their production racer to be competitive against even the factory-supported teams.

However, what is uncommon for this period is a privately built racer to be adopted by a Japanese factory through its European arm and used to win a World Championship. The story of the “Sankito” (an amalgam of the Japanese words for three and cylinder) used by Takazumi Katayama to win the 1977 350cc World Championship is indeed an unusual one.

The engine was offset due to the additional cylinder.

The origins of the Yamaha triple lay with Swiss sidecar racer Rudi Kurth, an innovative and talented engineer. Kurth had built a 500cc three-cylinder engine based on the twin cylinder Yamaha TD3 by having special crankcases cast that would accept an extra cylinder. Built specifically for sidecar racing, it proved, in 1976 form, that with a bore and stroke of 64mm x 51.8mm and a capacity of 499cc, to be more powerful than the World Championship winning Konig engine and was on a par with the hybrid Yamaha TZ 500 four-cylinder engine (TZ 750 crankcase and heads using TZ250cc barrels) but was lighter and more compact.

But although the genesis of the Sankito belonged to Kurth, it was former Yamaha racing mechanic Ferry Brouwer that developed the concept to a point that Yamaha Motor in the Netherlands adopted it as an official project.

Brouwer had been the race mechanic and friend to rising star Jarno Saarinen. But after Saarinen’s tragic death at Monza in the 1973 Nations 250cc Grand Prix, he decided to leave the Yamaha race team and take a job as the head mechanic at a new motorcycle dealership in Amersfoort Holland called Ton van Heugthen Motors. Ton was a successful sidecar motocross racer, and besides developing an XS 650 Yamaha powered outfit for his boss, with which he won the European Championship, Brouwer was also given the freedom to set up a road racing team to compete in mainly Dutch road racing events with Kees van der Kruijis as there rider.

During his years at Yamaha Ferry had developed an extremely good relationship with Minoru Tanaka who had run the factory race team. When Tanaka heard of Brouwer’s plans to set up the Ton van Heugten Racing Team running 250 and 350 Yamaha’s, he spontaneously offered some help by supplying spare parts and tuning data. Tanaka later mentioned that he had been in contact with Rudi Kurth and suggested that they visit him in Biel, Switzerland. Tanaka’s idea was to see if Kurth could make some crankcases, cylinders and cylinder heads for Yamaha so that T.v.H. Racing Team could build a 500cc three-cylinder solo racer.

With the modified bodywork the YSK3 had its own unique look.

After receiving the parts Brouwer built up the 500cc triple using standard Yamaha components. The bore and stroke were 64mm x 51.5mm giving an engine displacement of 496.7cc. The only non-standard piece of hardware was a German Krober ignition and Brouwer even used a modified TZ frame for the chassis.

While working on the 500cc triple one night, Brouwer came up with the idea of building a 350cc triple. By using the standard 54mm cylinders bore of the TZ 250cc machine and the splined crankshaft of the TD2 that had a stroke of 50mm, it created a capacity of 343.3cc with the added benefit that the individual crankshafts could be set at a 120 degrees firing order. Ferry rang Tanaka who organised the TD2 crankshafts, which Yamaha in Japan still had in stock and within a week work began on the 350cc triple.

The first race meeting for the 350cc triple was a Dutch Championship round at Mill. Although proving to be fast the triple was also unreliable as the crankshaft was causing problems. Brouwer suggested to Tanaka that they ask Hoeckle in Germany to make crankshafts for the 350 and 500 triples. Hoeckle crankshafts were being used successfully on TZ250 and 350 Yamaha’s and it would also give them the chance to increase engine capacity slightly. With the new crankshaft, it enlarged the stroke from 50mm to 50.5mm taking the capacity from 343.3cc to 346.79cc with greatly improved reliability.

Meanwhile, Van der Kruijis was having success winning several international races and the Dutch 250cc Championship on a TZ250cc Yamaha as well as finishing 5th in the 500cc class behind the likes of Wil Hartog, Boet van Dulmen and Jack Middleburg on the 500 triple. This success prompted Tanaka to enter the 350cc triple in the World Championship for 1977. The “Sankito” now was an official Yamaha Motor NV project and put in the care of 1973 and 1974 125cc World Champion, Swede, Kent Anderson who would with Trevor Tilbury develop the project.

The triple produced 15bhp more the TZ350cc twin.

Hard-charging Japanese, Takazumi Katayama and the legendary Giacomo Agostini were named as the riders for the 1977 season. Brouwer and his team would carry on developing the 500cc version building a completely new machine with a strengthened clutch by adding two plates and larger diameter carburettors and different port timing that boosted power output to 98bhp at the rear wheel. Nico Bakker supplied the frame and the new 500 became a real threat to the RG500 Suzuki’s.

Bakker also supplied frames for the official “Sankito” 350cc project although a standard TZ frame would also be available. At the same time, Spondon Engineering in the UK was asked to build a chassis as well. Brouwer and his fellow mechanics, Jerry van der Heiden and Melvyn Frey continued to develop the 500cc triple trying out ideas that would help improve the official “Sankito” project. The T.v.H. Racing Team still had a workshop to run and could only work on the race bikes in the evenings and weekends. Their hard work though resulted in a 3rd place for Kees van der Kruijis on the 500 in the 1977 Dutch Championship behind Grand Prix regulars Will Hartog and Boet van Dulmen.

But it was the 350cc “Sankito” that would prove to be a world-beater. By now the triple was producing approximately 15bhp more than the TZ twin and on a rainy March weekend it was entered in a Dutch national meeting at Tilburg and immediately set the fastest practice lap. Race day dawned with pouring rain and Katayama elected to use his TZ 350cc twin as the ‘Sankito” had revealed some handling issues in practice. The TZ 350 twin did the job and Katayama notched up the win. The next outing for the triple was in April at Mettet in Belguim and its performance was sensational. With no 350cc class to compete in Katayama ran the machine in the 500cc class. On the first lap, the engine would not fire cleanly putting Katayama in18th place before the motor came on full song. By the end of the race, he had passed numerous RG500cc Suzuki’s to take third place while closing in on the leaders.

Meanwhile, the World Championship had kicked off in Venezuela without either Katayama or Agostini. It was left up to Venezuelan and Yamaha’s 1975 350cc World Champion to represent the Yamaha factory, which he did in style with a decisive win riding the TZ350cc twin. The second round of the championship was in Austria at the Salzburgring and things did not go well, with Katayama crashing the “Sankito” in Friday practice necessitating a major rebuild for Saturday’s qualifying. Katayama could only manage 3rd on the grid but a major pileup during the race, including one fatality and Ceccotto breaking his arm, saw the race abandoned with no points awarded.

Katayama hard at work on the “Sankito”.

Next in the World Championship was the West German Grand Prix at Hockenheim and the result vindicated Brouwer and Tanaka’s belief in the “Sankito”. Both Katayama and Agostini were entered on the 350cc triple, but it was Katayama that romped away to win by over 15 seconds from Agostini. “Ago” had got a poor start, but in fighting his way up to second place he had also set a new lap record. Katayama had used the standard TZ chassis but felt its weight and the bulkier engine was detracting from even more potential performance.

At this point Agostini decided to concentrate his efforts on the Yamaha TZ350cc twin and Katayama also used the twin for the next round at the Italian Grand Prix at Imola, picking up a third place podium. The TZ350cc twin was proving more suited to handle the tighter sections at some circuits. Next came Jarama in Spain and another 3rd place for Katayama on the TZ350cc twin. The sixth round of the championship was the high-speed circuit of Paul Ricard for the French Grand Prix. As if to underline the potential of the triple, Katayama won the Grand Prix by over 24 seconds and also set a new lap record. This “Sankito” used the Spondon chassis although Katayama still was not happy with the handling.

When the chassis was destroyed in a fiery crash at a race meeting at Chimay in Belgium the Nico Bakker monoshock was put into service for the rest of the season. Katayama had broken his collarbone in the accident but it did not hold him back from winning the Yugoslavian Grand Prix at the Adriatic coastal town of Opatija. Coming from behind on TZ350cc twin he set the first 100mph lap of the circuit and established a 30-point lead in the championship.

Katayama suffered his first DNF of the season with a broken gear lever at the Dutch TT at Assen after fighting his way up to fourth, again on the TZ350cc twin. The points gap now narrowed to 18 over title rival Michel Rougerie who finished second. The Finnish Grand Prix at Imatra was next on the calendar, a track well suited to the “Sankito” triple. Despite a mediocre start in damp conditions and on slick tyres, Katayama would not be denied, winning by over 3 seconds and taking the 350cc World Championship title. Known affectionately in the paddock as “Zooming Taxi”, Takazumi Katayama became first Japanese to win a World Championship. Of the eight rounds, he contested he claimed five 350cc Grand Prix victories two third place podiums and a DNF. Three of his five victories were on the adopted “Sankito” and two on the official TZ350cc twin. In fact, apart from the abandoned 350cc Austrian race, the “Sankito” won every Grand Prix it was entered in.

Katayama on his way to becoming Japan’s first World Champion.

Politics at Yamaha Japan now started to play out, as the factory was not interested in developing the 350cc triple. Their main focus was the TZ twin cylinder racers whose bloodline could be traced back to the road going models the company sold. The “Sankito” once again became a mainly private project for 1978. Separate cylinders were cast to replace the one-piece block of the previous year and Lectron carburettors, as well as a White Power monoshock, were used. It also had the expansion chambers reversed with two exiting on the right and one on the left.

This last version of the “Sankito” was shipped to Venezuela for the first 350cc Grand Prix of the 1978 season for Katayama to use but problems with the machine saw him revert to the TZ 350cc twin to win the first race of the season in his title defence. At this point, the “Sankito” project was abandoned, as Yamaha Japan had no real interest in developing this unique triple any further.

Words © Geoff Dawes 2017. Images courtesy of http://www.cml.blogs.editions-lva.fr, http://www.icpbrasil.wordpress.com, http://www.vk.com

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The 1982 NS500 and 1984 NSR500 Grand Prix Racers.

 

The Honda NS500 V3.

The Honda NS500 V3.

When Honda made the decision to return to the premier class of Grand Prix motorcycle racing in 1975 it did so with a great deal of optimism. The Japanese company had withdrawn in 1967 for numerous reasons (see the Honda NR500 story) yet when it officially announced its return in 1977 the 500cc Grand Prix landscape had shifted dramatically. The two-stroke racing engine reigned supreme; even the four-stroke Grand Prix racers of the mighty MV Agusta team had withdrawn in 1976 leaving a two-stroke monopoly on the class. Honda’s Japanese rivals, Yamaha and Suzuki, had by now both won 500cc world titles, Yamaha winning Japan’s first 500cc World Championship with the great Giacomo Agostini in 1975 and Suzuki winning titles in 1976 and 1977 with the talented Barry Sheene. This must have been a severe “loss of face” for Honda who pioneered Japan’s first foray into Grand Prix racing.

And the decision by Honda to build a four-stroke racing engine within the limitations of the regulations was a bold one. Honda’s approach reflected the philosophy of the companies’ founder, Soichiro Honda, a stalwart of the four-stroke design. However, the plan documents for Honda’s “New Racing” engineers stipulated three years to win the world championship. By 1982 it was clear that the four-stroke racer was unlikely to get on even terms with the two-strokes. In a racing sense the oval piston eight-valve NR500 V4 was indeed a racing failure, but as a technical exercise it was an outstanding achievement.

But regardless of Honda’s aversion to the two-stroke engine, it did have experience with the concept going back to 1974 with the release of the highly successful Honda Elsinore CR125 and CR250 motocross racers. Veteran engineer Shinichi Miyakoshi, who had designed four-stroke GP machines for Honda that dominated Grand Prix racing in the 1960’s, was assigned to the task of developing Honda’s first two-stroke GP racer. The experienced Miyakoshi had been designing two-stroke engines for the motocross group within Honda, which proved to be invaluable to the gestation of the new two-stroke NS500 Grand Prix racer.

Spencer in action on the NS500 V3.

Spencer in action on the NS500 V3.

In June 1981 Miyakoshi visited the Dutch TT at Assen in Holland. There he noted that the fastest of the 350cc GP machines would have qualified on the second row of the grid for the 500cc race. Hence the concept for the NS500 became one of a compact and light machine with a small frontal area of a 350cc GP racer. The engine would be designed for usable power and optimum control, not top speed. A compact V3 layout was chosen using reed valves for smoother power delivery and easier starting (push starts were mandatory at that time). The idea was to have a machine with total balance and again Honda would utilise its motocross experience for the suspension of the NS500. Interestingly the V3 engine configuration had been used before. German manufacturer DKW had utilised it in the 1950’s for its 350cc GP racer. The NS500 also used similar engine architecture to the DKW with two upright cylinders, but unlike the DKW the third cylinder pointed downwards at 112 degrees instead of the more conventional 90 degrees of the DKW.

DKW's air-cooled 350cc V3 two-stroke engine.

DKW’s air-cooled 350cc V3 two-stroke engine.

Another major part of the NS500’s rationale would be its ability to maximise its tyre wear. Racing slicks at this time were still using bias belt construction and the harsher power characteristics of the more powerful rotary valve engines from Yamaha and Suzuki punished the tyres, particularly towards the end of a Grand Prix. The more agile Honda would be able to maintain higher corners speeds for longer, which would negate to a certain degree its lower top speed down the straights.

The NS500 debuted in 1982 in the hands of reigning 1981 World Champion, Italian Marco Lucchinelli, whom Honda had lured away from Suzuki. Korean born Japanese Takazumi Katayama was again part of Honda’s 500cc rider line-up alongside the promising 20-year-old American Freddie Spencer who was promoted full-time to the Grand Prix squad.

It was not until the seventh race of the season in Belgium at the Spa Francorchamps circuit that Honda tasted victory. The win was Honda’s first in15 years and remarkably it was at a circuit renowned for its high speed. And it was “Fast” Freddie Spencer that had ridden the NS500 to victory, his main opposition suffering tyre and mechanical problems. By the end of the season, Spencer had won two races (Belgium and San Marino) and achieved three podiums. Katayama also won the Swedish Grand Prix, but this was just a taste of what was to come.

Spencer chases Takazumi both on the NS500.

Spencer chases Takazumi both on the NS500.

The 1983 season saw an epic battle between “King” Kenny Roberts and “Fast” Freddie Spencer. At the penultimate round in Sweden Spencer had claimed a forceful victory with Roberts running off the track before finishing in second place. In the twelve round race series, it was Spencer that had accumulated six race wins to Robert’s five. If Roberts won at the last round in San Marino Spencer would have to finish second to claim the championship. Indeed Roberts won in Italy, but despite slowing tactics by “King” Kenny in an attempt to put his teammate Eddie Lawson between them, Spencer was still able to finish in second place claiming Honda’s first 500cc World Championship by two points.

Although the lateral thinking behind the V3 triple had borne the fruit of victory it was clear to Honda that with the introduction of radial racing slicks and the limitations of the Honda’s V3 engine architecture that a V4 would be needed against the more powerful opposition from Yamaha and Suzuki for the 1984 season. Honda decided to enter the power war, but again in typical Honda fashion.

In contrast to the twin crankshaft OW76 Yamaha V4 and the twin crankshaft Suzuki RG500 XR45 square four, the 1984 Honda NSR500’s 90-degree V4 used a single crankshaft as this design reduces frictional losses to maximise horsepower. But if anything it was the chassis of the ’84 NSR500 that pushed the envelope.

Honda had been supplying its four-stroke RSC1000 endurance-racing engine to the avant-garde ELFe endurance racer. With the financial backing of the French oil company ELF and Honda itself, Andre de Cortanze and his team had devised a radical alternative to the conventional motorcycle chassis. Using a single sided swingarm at the rear for quick wheel changes, the front also boasted twin swingarms utilising a steering system that could loosely be describe as hub centre steering that again allowed the front wheel to be removed from one side. The objectives of the ELFe were “reduced weight, lower centre of gravity, improved anti-dive under braking and elimination of a conventional chassis”.

Freddie Spencer and the innovative NSR500 Honda.

Freddie Spencer and the innovative V4 NSR500 Honda.

The lower centre of gravity of the ELFe was achieved by mounting the fuel tank under the engine with the exhaust exiting over the top of the engine. It should also be noted that English endurance race team Mead and Tompkinson preceded the ELFe with their creation nicknamed “Nessie” in the mid 1970’s which used Difazio hub centre steering and the same under engine fuel tank and above engine exhaust layout. But it was the ELFe that the Honda engineers took inspiration from. Although retaining a conventional suspension layout, the lower centre of gravity of the ELFe underslung fuel tank was deemed a desirable asset.

The NSR500 first appeared at the 1984 Daytona 200 in Florida, and the initial result was promising with Freddie Spencer setting a lap record of 116.87mph (188.08kph) in qualifying to take pole position. During the race though, tyre problems and a slipping clutch relegated Spencer to second place behind Kenny Roberts. But two weeks later at the opening round of the 500cc World Championship at the Kyalami circuit in South Africa disaster struck. During practice another innovation of the NSR500 V4, its carbon fibre composite rear wheel, collapsed causing Spencer to crash and sit out the race.

The reigning World Champion bounced back, however, to win the Italian Grand Prix at Misano on the V4. This was then followed by another crash while leading the fifth leg of Trans-Atlantic Challenge races at Donnington. This forced Spencer to miss the Spanish Grand Prix at Jarama, returning to race at the Austrian Grand Prix at the Salzburgring. It was clear to the spectators watching the race that the NSR500 V4 had handling issues, especially under power exiting the esses onto the main straight. Indeed Randy Mamola on the factory Honda NS500 V3 allowed his team leader through to take second place behind championship leader Eddie Lawson infuriating the crowd who showed their dislike by booing Spencer and Mamola on the slow down lap.

Spencer's chief engineer Erv Kanemoto and mechanic George Vukmanovich walk the V4 NSR500 back from the pits in Austria.

Spencer’s chief engineer Erv Kanemoto and mechanic George Vukmanovich walk the V4 NSR500 back from the pits in Austria.

Freddie by now was getting desperate to bridge the points gap to Eddie Lawson and demanded the NS500 V3 for the next race at the Nurburgring. A mad dash was made to take Marco Lucchinelli’s NS500 out of mothballs in time for the race which Spencer duly won on the V3. This was a bitter pill for Honda to swallow and an embarrassment to a company where new is seen as better. The problem lay with the underslung fuel tank, which by lowering the centre of gravity also affected weight transfer under braking and acceleration which was not generating enough force onto the front and rear tyre, thereby reducing grip. Heat build up from the over the engine exhaust system was also a problem as it heated the air going into the carburettors. The positioning of the expansion chambers themselves also made it difficult to check and change spark plugs and to undertake fine tuning of the carburation, all crucial to a two-stroke racing engine within the time limitations of the practice sessions.

Spencer somehow went on to win the next two Grand Prix on the V4 at Paul Ricard in France and Rijeka in Yugoslavia. The next race was the Dutch TT at Assen. After practicing on the V4 Spencer decided to switch to the V3 for the race after practice had finished. This was scuppered by the supplementary regulations and Freddie was forced to start on the V4. A broken spark plug cap put an end to Freddie’s race as the title started to slip further from his grasp. Again Spencer opted for the V3 for the Belgium GP at Spa and again won the race. Then once more fate played a hand with Freddie crashing at an international meeting at Laguna Seca in California. The crash re-broke an old fracture Spencer had suffered two years before so the reigning World Champion would miss the three final races of the season at Silverstone in Britain, Anderstorp in Sweden and the San Marino GP at Mugello in Italy. This effectively handed the riders World Championship to Honda’s great rival Yamaha and gave Eddie Lawson his first world title. Honda did have the consolation of winning the manufacturer’s trophy, but this was more due to the number of factory, factory supported and privateer riders competing on the NS500 V3.

Randy Mammal on the NS500 V3 leatds Eddie Lawson on the Yamaha V4 Yamaha, Ron Haslam V3 Honda and Spencer V4 Honda.

Randy Mamola on the Honda NS500 V3 leads Eddie Lawson on the Yamaha OW76 V4 , Ron Haslam Honda NS500 V3 and Spencer on the Honda NSR500 V4 in Austria.

It would be unfair to say the 1984 NSR500 was a disappointment; the V4 did win three GP’s and a podium second place. Considering Spencer only contested 6 of the 12 rounds (missing 2 races through mechanical problems and a further four races through injury) fourth place in the rider’s championship was quite a remarkable achievement for Freddie.

Spencer also won 2 GP’s on the NS500 V3 while Randy Mammola won 3 GP’s and accumulated 5 podiums also on the V3 Honda. Which begs the question, would Spencer have defended his title had he campaigned the proven NS500 V3? Hindsight, of course, is a wonderful thing, and one has to admire Honda for empowering its engineers to look for new solutions with the 1984 NSR500. The single crankshaft V4 engine, however, more than lived up to Honda’s high expectations and the NSR500’s that followed, utilising a more conventional chassis, became the most successful 500cc machines in Grand Prix racing history.

Words Geoff Dawes © 2016. Photographs © Geoff Dawes 1984 and courtesy of http://www.blogs.yahoo.co.jp, http://www.commons.wikimedia.org, http://www.s307.photobucket.com, http://www.southbayriders.com.

Below is a short documentary about the NS & NSR 500 Grand Prix racers courtesy of Honda.

The NR500 Honda

There is an age-old adage that “necessity is the mother of invention”, which is an apt description of the challenge that the Honda Motor Company faced on its return to the 500cc class of Grand Prix motorcycle racing in 1979.

Honda had withdrawn from motorcycle Grands Prix at the end of 1967 for a variety of reasons. The Japanese company had prioritized the R&D department to concentrate on its venture into road cars, while also supplying racing engines to the Brabham Formula 2 team and entering its own car into Formula 1 with former motorcycle and F1 world champion John Surtees at the wheel. The company’s resources were being stretched to the very limit.

And there were also changes in the wind for Grand Pix motorcycle racing with new regulations being introduced by the F.I.M. at the end 1969 season, which would limit the number of cylinders and gears for the different Grand Prix classes, in an attempt to reduce costs, that also played a part in the decision by Honda to withdraw.

During the mid sixties, Honda, a stoic champion of the four-stroke engine, had been fighting a rearguard action against the ever-improving two-stroke engines of its Japanese and European rivals, particularly in the smaller capacity classes. To overcome the more frequent power strokes the two-stroke engine design, Honda could only improve the four-stroke engines volumetric efficiency with more cylinders, higher engine rev’s and more gears, which were effectively to be outlawed by the FIM in 1969.

How could Honda respond to this technical conundrum? The answer is one of the most technically innovative motorcycle engine designs of all time.

The NR500's revolutionary  engine.

The NR500’s innovative engine.

The decision to return to the Grand’s Prix was officially announced in December 1977 by the President of Honda, Koyoshi Kawashima. In true Honda tradition the group of young engineers brought together to develop a winning machine had little if any racing experience. This “clean sheet” approach was indeed a risky one. No four-stroke had competed in the 500cc class since 1976 when the mighty MV Agusta team withdrew, conceding to the supremacy of the two-stroke engine.

With the official title of “New Racing”, the development team came together in 1978 at the Asaka R&D Center. Takeo Fukui, who would later become director of R&D and president of Honda Racing Corporation, would lead the team, while Soichiro Irimajiri, the man who was the father of the CBX road bike and the fabled RC166 250cc six-cylinder GP racer would help guide the group. It soon became clear to the young engineers that, within the limitation of four cylinders, to get on a competitive footing with the two-strokes they needed to double the number of engine revs and improve intake efficiency by doubling the number of inlet valves from four to eight. To accommodate eight valves the team decided to free themselves from the traditional round piston and use a revolutionary oval design. In effect a V8 with 4 sets of two cylinders fused together. According to their calculations an estimated output of 130hp at 23,000rpm was possible.

Cylinder head for the Honda NR500.

A cylinder head for the Honda NR500.

To prove the potential of this design a single cylinder “slave” engine was built, initially with two valves, which proved the engine would rev. The number of valves was then increased step by step to eight valves. This was not without teething problems with the engine self destructing at anything over 10,000rpm. The problem was with the two connecting rods the oval piston design required, which distorted and pulled the piston pins out of position. Sealing of the piston rings, not unexpectedly, was also a major problem.

However, it was the persistence of the team that one by one identified and found solutions to these problems. The achievement of effectively sealing of the piston ring in particular was a considerable boost to the feasibility of the overall design. With that, the test target moved from the single-cylinder ‘slave” engines to a full four cylinder engine.

Toshimitsu Yoshimura was responsible for designing the 100-degree V-four and bench testing of the revolutionary engine began in April 1979. The Grand Prix season was already well underway. But the 0X engine was still giving the team problems, from a damaged gear train to broken valves. Nevertheless, the engine was producing around 110 horsepower, and the engineers knew that to understand its real world potential it needed to be assessed in the white heat of competition. “We wanted to identify the weaknesses in our new engine by seeing how it performed in an actual race,” remembered Yoshimura.

Oval piston from the NR750 Honda.

Oval piston from the NR750 Honda.

However, it was not just the engine of the NR500 that was innovative, the chassis was as well. Designed by research engineer,Tadahashi Kamiya, it was constructed as a true monocoque. The engine, with swingarm attached, slotted into the stressed skin of the fairing, tank and seat unit. Radiators for the liquid cooled engine were mounted on the sides of the fairing, utilizing the air funneling through the front of the “fairing” to flow onto the engine and out the sides of the fairing through the cooling radiators. Although the rear suspension was a more conventional monoshock system the front forks were unusual by using an “upside down” design in which the triple clamps held the fork tubes and the stanchions held the front wheel axle. The Honda design used external fork springs to enable quick changes of spring rates and a greater volume of fork oil and larger damping components in the fork tube.

Oddly the disk calipers where mounted in front of the forks, which to a degree was offset by an unusual trailing front axle. Again the team of engineers pushed the envelope by opting to use 16inch Comstar wheels with tyres developed by Dunlop as opposed to the commonly used 18inch rims with Michelin tyres in search of a lower unsprung weight and a smaller frontal area for the NR500.

The revolutionary NR500 Honda of 1979.

The ground breaking NR500 Honda of 1979.

It was at the 1979 British Grand Prix at Silverstone, the 11th World Championship race of the season, that the NR500 made its debut. Veteran English rider Mick Grant, an Isle of Man Senior TT and 250cc Grand Prix winner, along with Takazumi Katayama, a Korean born Japanese rider and 1977 350cc World Champion, had been recruited to race the groundbreaking machine. Both had tested the bike in Japan and Grant in particular understood the frustration of developing the avant-garde Honda.

“By that time I knew what to expect.” Commented Grant. “They had open practice and on the straight a 250cc Yamaha was pulling away from me – not a lot, but pulling away and that was enough to show me the scale of the problem. I had never ridden harder.”

Even with Grant and Katayama’s best efforts they qualified on the last row of the grid. Grand Prix racing in those days required a push start by the rider to fire up the engine when the starters flag was dropped. The Honda at that stage would only idle at 7000rpm and getting the engine to fire up was a hit and miss affair. Katayama caught his engine but waited for Grant’s engine to fire so they could circulate together around the circuit. It took several embarrassing seconds before Grant could get away. With his weight too far back on the saddle the Honda pulled wheelies through the gears. As he approached the first corner the NR500 slid out beneath him and started to catch fire. The wheelie had caused oil to spill out the carburetors and onto the rear tyre. Katayama retired several laps later with engine problems.

The revolutionary oval piston technology.

The revolutionary oval piston technology.

The next race was the French Grand Prix at Le Mans where the Honda team suffered the humiliation of not even qualifying for the race. It was the last race of the year and Yoshimura was moved to tears, “I felt miserable, just miserable,” he said. “Tears welled up in my eyes. Except for ours, all the bikes were using two-stroke engines. To be honest, I’d been hoping they would go to the final race and give us a really good run, even if it meant trailing at the very end. After the race they asked me to watch the video, but I couldn’t bring myself to see it.” If anything it underlined how long the road would be for the NR500.

In fact the plan documents for the “New Racing” team had stipulated, “Become World Champion within three years.” Time was of the essence and the vast amount of new technology and innovation would take to long to perfect.

At the beginning of the 1980 season the team had returned to a conventional tube type frame and 18inch wheels. The focus could then be put into developing the engine, which in many ways was the fundamental problem. Due to the V4’s extreme engine breaking which caused the rear wheel to hop on downshifts in the lower gears, a back torque-limiting clutch was developed to cure the problem. By now the 1X engine was producing 115ps, but acceleration and throttle response in corners was still a problem. And as reliability improved so did the engines weight by around 20kg requiring the use of exotic materials such as magnesium and titanium to maintain the status quo.

The tube frame  for the 1980 NR500.

The tube frame for the 1980 NR500.

The 1980 grand Prix season however did not see much reward for a lot of hard work. Although Katayama had managed take a third place  podium at an international meeting in Italy, in the World Championship his best results were fifteenth place at the British Grand Prix (the first finish for the NR500 in a GP), and twelfth place at the German Grand Prix. This did not stop the motorcycle media from harshly criticising the NR500 Honda, tagging it as “Never Ready”.

The oval piston engine was further refined for the 1981 season in order to reduce weight, improve durability and increase power. The 100-degree V of the engine was narrowed to 90 creating a more compact unit but just as importantly it was now producing 130ps at 19,000rpm in its 2X configuration.

Freddie Spencer on the NR500 Honda at Silverstone.

Freddie Spencer on the NR500 Honda at Silverstone.

Honda had decided it would enter machines in the All-Japan Championship to help speed up development of the NR500. A fifth place at the second round of the championship saw the NR500 starting to compete on more equal terms with two-strokes. This was backed up with the NR500’s first win at the Suzuka 200 kilometre race where the four-strokes better fuel consumption was pivotal to the victory. Then in July Honda’s new rider signing, Freddie Spencer, scored a victory over 500cc Grand Prix World Champion “King” Kenny Roberts in a heat race for the final in an international meeting at Laguna Seca.

The NR500 (2X) machine that helped Kengo Kiyama to win the 1981 Suzuka 500-Kilometer Race, giving Honda its first victory with the oval piston engine

The NR500 (2X) machine that helped Kengo Kiyama to win the 1981 Suzuka 200-Kilometer Race, giving Honda its first victory with the oval piston engine

The competitiveness did not follow the Honda to Europe. Katayama managed a thirteenth place at the first round of the 500cc World Championship in Austria, but retirement from the subsequent races resulted in no points for the team that season.

For the 1982 season, after finally accepting that the rules favoured the two-stroke engine, Honda introduced the NS500 two-stroke Grand Prix racer. Although race appearances became fewer for the NR500, bench testing of the remarkable engine continued.

The technology continued to be developed resulting with the gestation of the NR750 to race at the 1987 Le Mans endurance race in France. Although not expected to win, (that was the job of the more “conventional “ Honda RVF’s of Honda France) and with two of rider line-up whom were motorcycle journalists, it was up to two time Australian Superbike Champion, Malcom “Wally” Campbell, to qualify for the race. Someone forgot to tell Campbell that for Honda it was more about publicity than racing and he put NR750 in second place on the grid behind the factory Honda RVF. Unreliability again put the NR out at the 22hour mark, but it did emphasise  how far the technology had come. Campbell would give the NR750 its first win in a heat of the Swan Insurance International Series at Calder Park in December that year.

The 1992 NR750 Honda.

The 1992 NR750 Honda.

In 1992, thirteen years after the NR500’s debut in the World Championship Grands Prix, Honda unveiled a production version of the NR750. Around 300 of these machines are believed to have been made with an extremely high price tag of around US$50,000. Recently an example was placed on eBay with an asking price of approximately US$100,000.

There is also a certain amount of irony that Formula 1 banned both oval piston and two-stroke technology for use in an F1 engine.

Perhaps a quote by an unnamed engineer that worked on the project best sums up the NR.        “ The true value of the engine lay in its remarkable potential”.

Words Geoff Dawes © 2015. Images courtesy of Honda Worldwide. Video courtesy Honda Worldwide, MCN and Youtube.