SENSATIONAL SIX!
Honda’s CBX was first sold 40 years ago this summer. John Nutting, who was at its launch, recalls its impact and talks to Honda UK executive Gerald Davison who rode the prototype in 1977 and has enjoyed a four-decade love affair with the six-cylinder supe
Forty years ago this summer, TT fans in the Isle of Man got their first view of Honda’s CBX in action when it was used by the travelling marshals. Although for news value the use of the new six-cylinder superbike on the 37.73-mile Mountain circuit was partly overshadowed by Mike Hailwood’s legendary return in 1978 after an 11 years absence from the island, it was a great coup for Honda. The appearance of the CBX at the TT that year was the result of a last-minute effort by management at Honda UK to have four machines flown from Japan, and the culmination of just over two years of research and development that started at the beginning of 1976. At the time, Honda had been refocusing its efforts after a reorganisation with a new R&D facility and motorcycle division at Asaka near Tokyo headed by Shoichiro Irimajiri, the still-young engineer who had been responsible for some of Honda’s racing engine designs that had been so successful in the 1960s. Irimajiri had already been responsible for some innovative and unique road bike designs, leading the team that developed the Gold Wing tourer launched for 1975 and the equally-novel CX500. In the spring of 1976, Irimajiri created a project team to develop two motorcycle engines, one with four-cylinders the other with six but both with double-overhead camshafts and four-valves per cylinder, the arrangement used on the earlier racing machines that offered more potential for power than the single-overhead-cam two-valve set up used until then on Honda’s four-cylinder road bikes. Independently, the Honda Racing Service Centre at Suzuka, under former GP team manger Michihiko Aika had revived its racing programme with special machines developed for endurance events in Europe. These were based on the CB750 Four and featured DOHC 16-valve heads and gear drives and known as the RCB1000. Gerald Davison was at the time senior manager of Honda UK. After forming the Honda Britain Racing Team, which among other things raced the RCB, he would later become Honda UK’S director of operations and set up what would become HRC. He recalls being involved in the decision-making process that would influence the final design of the CBX. “After the tremendous success of the Cb750-derived DOHC RCB endurance racers and the very successful, but interim, update to the road bike in the form of the CB750F2, I was really anxious that we add an entirely new sports model to the top of our range to maintain our competitive edge,” said Davison, who is now retired and lives on the Isle of Wight. “There were now other Japanese four-strokes beginning to eat into our market position with more up to date specs. Although rumoured inside the company to be the
answer, the Gold Wing when it appeared was not the answer for Europe, being much more suited to the US market. Nevertheless, it soon developed quite a following as a tourer and eventually created its own niche in the market. But it wasn’t the ‘Super Sport’ we needed. “At Honda we were used to the constant plaudits for and sales domination of our increasing fourstroke range of four-cylinder models and suddenly our thunder was being stolen by others. We were also smarting from the ‘Universal Japanese Motorcycle’ moniker that was increasingly used by the press to criticise almost all new models coming from all Japanese manufacturers who were accused of bland designs. What we urgently needed was a machine, both lean and fast. “I had already started the V4 discussion within Honda during 1976 but I knew that it would have to wait until we moved to water-cooling, not only for reduced emissions but for rear-cylinder cooling. I was being reassured that at last something was coming that would fill the gap at the top of our sports bike range and provide the then much vaunted ‘halo effect’ for our entire line-up. There was tremendous secrecy surrounding the engine configuration of the new model, known internally as ‘The King’ – I began to imagine at first the DOHC CB750F and CB900F fours that finally appeared just a little later in 1978.” The new four- and six-cylinder engines were developed in parallel for six months. At that point it was decided by Irimajiri that the six, with its more pleasing high-revving exhaust sound, had more potential than the four. He also wanted to design an engine that rivals would find difficult to match and that harked back to early racing successes. “The six was a piece of Honda’s heritage,” says Davison. Project 422, as it was called, was led by Shunji Tanaka, with engine design by Masahuri Tsuboi and the styling by Minoru Morioka: an early mock-up of the six shows that various parts were used from a number of models, but what is interesting is that this was based on OHC CB750 crankcases, with the cylinder block and head welded up from CB750 components, and topped by dummy camshaft covers and drive. The design team viewed this monster of an engine and concluded that it was “impossible”. “This would be a motorised brick wall,” they said, adding, “Do they expect us to build a frame to carry this monster?” Work concentrated on getting the best riding position around the massive engine which was finalised using a layout similar to those found on the
“Early tests were supervised by Yoshio Nakamura, designer of the Nakajima Sakae radial engine used in the Second World War Mitsubishi Zero fighter”
Grand Prix racers. To keep the engine as narrow as possible, the alternator and ignition units were located behind the cylinder block above the gearbox. A number of styling ideas were tried before creating full-size clay models. Irimajiri later described the development of the CBX in a letter to Mike Brown of the US CBX owners club, who had invited the engineer to one of its rallies in 1990. “The biggest problem with the CBX was the weight,” said Irimajiri. “In order to guarantee sufficient horsepower, the weight had climbed to over 200kg and how to get it down was our biggest headache. This fact became extremely clear on the test track, but nevertheless we felt there
was something exhilarating and exciting about the six-cylinder CBX that was lacking in the four-cylinder version. The deep rumble of the exhaust, the feeling of acceleration, the vibration, its smooth high-rev engine – something in the CBX could not be measured in numbers like speed and weight that made it a very sexy machine.” Davison first saw what would be the CBX when he was in Japan early in 1977 to ride the prototypes. The early tests were supervised by Honda main board director Yoshio Nakamura, designer of the Nakajima Sakae radial engine for the Second World War Mitsubishi Zero fighter and Honda’s early Formula 1 V12 engines. “The morning mist at the Suzuka circuit was just starting to lift when the covers came off the prototype new model that I was so anxious to see,” said Davison. “I was not prepared for the stunning prototype that emerged. When the early sun breaking though the mist picked up the highlights of its massive engine and exhausts I have to admit
this was not so much love at first sight – more likely pure lust! And so began an affair between the CBX and myself that has lasted undimmed now for 40 years! Starting the engine for the first time was also an experience that matched its looks. I had ridden faster bikes but to feel for the first time the turbine-like balance of six cylinders was unique. Revving very freely without any notable vibration it was impressive. “Of course, today’s superbikes can easily outperform this 40-year-old giant but they still can’t deliver that mid-range punch with such élan. Cornering was never a problem, even with the narrow tyres used then and many of the later tales of poor handling were down, I believe, to inexperience or heavy-handed riding. It was possible at very high speed to get something of a weave going but this was in the main due to suspension settings and was not difficult to control although it looked much worse to track-side observers. In fact after a couple of hours that morning at Suzuka, I was becoming so enthusiastic that I got black flagged by Nakamura. It wasn’t a big deal at the time. I think this ultimately led to company President Kawashima ensuring that I stopped testing a year later when I became director of the GP racing team.” The design of the CBX was completed in March 1977 and its name changed from Super Magnum to Super Sport. By the summer of that year a batch of 40 pre-production Z models were made for testing, photography and press launches. These machines differ in a number of details from the eventual production versions and most of the batch was scrapped, but a number survive in private hands and can be identified easily by their lack of a bolt at the extreme ends of the cylinder head. Motorcycle magazines had been aware that a new sports Honda was under development but, even so, were shocked when Irimajiri revealed pictures of the CBX during the launch of the CX500 in France early in December. The speed at which events that would lead up to the launch was intense. To meet the needs of American magazines, bikes were made available there in October, while another batch was prepared for the international press launch in Japan just before Christmas in 1977. I was one of the motorcycle press contingent invited to test the bike. The CBX was fantastic, both in its style and specification and the way that Honda’s project team had managed to create a practical motorcycle. It was nothing like as bulky as I’d expected. Of course you could see the cylinder heads below the nose of the fuel tank – at 23½in across you couldn’t miss them – yet they were only slightly wider than the CB750 Four. Being canted forward 30º the cylinders were well out of the way. Up front the controls and instruments – all black and purposeful – presented an image of barelycontrolled potency waiting to be unleashed. The use of an ammeter between the clocks helped reinforce the image of functionality. Detailing was exquisite with cable adjusters machined from aluminium alloy to keep the weight low. The twistgrip, with its twin cables looping up and clear of the frame,
provided just a quarter turn to full throttle, just like race bikes. The test bikes had been brought to the pit lane already warmed up so a touch of the button brought them to life: and what a sound. A snap of the grip was pure joy as the revs jumped and the rev needle danced into action towards the red line at a heady 10,300rpm. With claimed peak power of 105bhp at 9000rpm, the engine and its specification read like science fiction. The six 64.5mm pistons and the 53.4mm stroke of the one-piece crankshaft with 120º spacings added up to 1047cc. Thanks to the centre chain drive to a countershaft, it was slim across the five-speed gearbox and clutch cover, so the footrests and levers – lovely forged-alloy items – were narrow. It didn’t feel bulky, making the sensation of being in control of naked power all the more intoxicating. Full production of the CBX then started early in 1978 with engines being made at the Wako factory and shipped for assembly into the rolling chassis at Sayama: demand was so great that getting the bikes for use by the travelling marshals at the Isle of Man TT in June was a struggle. Roger Etcell, who later became manager of Honda UK’S motorcycle division, recalls that it took a last-minute effort to get the bikes to the island. “Honda had committed to providing half-a-dozen bikes for the travelling marshals, and the plan was to use the CBX, but they were coming late off the production line in Japan,” he said. “We had some of the new CX500 V-twins, but we really wanted the CBX. We campaigned vigorously to get the factory to fly four machines from Japan to us. They arrived at Heathrow on the Thursday evening before the TT fortnight and we took them straight to Honda UK’S base at Chiswick where we prepared them overnight. On the Friday we rode them to Liverpool to catch the ferry to the Island. Yorkshire dealer Padgett’s looked after them, fitting crash bars. It was really close!” Allan ‘Kipper’ Killip, now 85 and chief travelling marshal at the
time, remembers the CBX well. “I was happy with the bike and had no problem with it,” he said disarmingly from his home at Crosby on the Island. “But we weren’t racing, just doing a job.” Everyone who came in contact with the CBX was amazed that a machine that so effectively evoked the memories of Honda’s glory days could be developed so quickly. In almost every way, the CBX was miles ahead of any other mass-produced bike at the time of its launch, 40 years ago. Gerald Davison remained enthralled by the CBX and over the years regularly visited his former boss Shoichiro Irimajiri, who rose to head-up Honda’s US car operation before returning to Japan as a board director. “Riding the CBX today still has some of that wonder about it and I always liken it to dancing with an old flame,” said Davison. “Since those early days I’ve maintained my affair with the model initially through a ‘red head’ in the 90s and more recently a ‘silver grey’. The Perseus Silver version was always my preferred choice and when a little used, low mileage one turned up in an H&H auction a few years ago I just couldn’t resist it. It had a strange history in that it was a UK model but shipped to the USA. The UK could not sell all of the units imported for 1979-80 and so some were shipped out. It had come back to Europe and then sat in a German museum for the next eight years. The bike was very original apart from a USA market exhaust system (identical to the original) and missing mirrors. “Although it started easily, re-commissioning needed to be very thorough, starting with new tyres and brake lines. It was sporting a kph speedo and I was lucky to find a NOS mph replacement. Overhauling the six carbs is a major task as it entails almost removing the engine to get at them and likewise the tappets need the use of a shimming kit. All in all, including UK registration, it was about six months before it was on the road. Apart from riding it regularly, work during the winter each year (in addition to regular maintenance) has included continuous gentle restoration dealing with a few issues at a time. Never having been too keen on ‘over’ restoration this has often been a matter of small paintwork and chroming jobs. The main items like the tank are still sporting original paintwork but many small items have been powder-coated, always trying to keep the bike as close to its original spec and appearance as possible. It was heartbreaking for example, when the original seat cover split but the replacement is at least a very accurate copy.” Due to ill health, Davison recently sold the bike, through H&H again, for almost £15,000 including commission/taxes. Overall, slightly less than 36,000 CBXS were made, including 24,500 Z models and 4950 A models, 3754 B models and 2737 C Pro-link models. Of these, 2500 Z examples were imported in the UK – at a price of £2750 plus £18 delivery charge – and one A model. Around 350 Pro-link CBX versions came to the UK and many serve as a more affordable base for specials to those who want that lusty roar of Honda’s very special six-cylinder motor. Here’s to the next 40 years!