The 1980s was a time of rapid developments for motorbikes. While European companies floundered, Japanese brands innovated and so much good stuff that we now take for granted: fairings, four-valve heads, water-cooling and even anti-lock brakes emerged and became commonplace throughout the decade. By the time the Eighties rolled into the Nineties, the Universal Japanese Motorcycles (UJM) was a thing of the past, replaced by more focused and technologically advanced machines we could barely have believed 10 years earlier.
But not all the ideas that appeared in the Eighties were a success. As all the Japanese manufacturers experimented with their own technology, not all would succeed. It is to these failed ideas that we’d like to pay tribute…
16” front wheels
If you ride a modern street or sports bike, chances are it’ll have 17” wheels front and rear – with fairly standardised tyre sizes between the various manufacturers’ models.
But that wasn’t the case at the start of the 1980s. Most sporty bikes ran 18” wheels, shod with skinny crossply tyres, but by 1981 Grand Prix race teams were experimenting with smaller, 16” wheels.
The theory is simple. A smaller wheel is lighter and more agile, and the concept quickly found itself trotted out to street bikes. If you rode a Honda VF750F, Suzuki GSX750EF or a Yamaha FZ750, among many others, your bike rolled out of the factory with a 16” hoop up front.
The problem was that while the smaller wheel gave a quicker turn in, it compromised the bike’s stability and gave less rider feedback. As tyre technology improved and radials came in, riders failed to see the benefits of the smaller wheels and 17-inchers became the industry standard.
Not that it was the end of the 16” wheel. As part of his uncompromising design brief, legendary Honda designer Tadao Baba specced a 16” front for the original CBR900RR FireBlade in the early 1990s. While he achieved his aim of saving weight and creating razor sharp handling, the design polarised opinion and made finding aftermarket rubber a chore. Since 2000, the FireBlade joined the other sports bikes by switching to 17” wheels up front.
Five valve heads
In the 1970s, motorcycles (and all but the most high performance cars) had two valves per cylinder – one for the inlet and one for the exhaust.
By the early Eighties, high performance street bikes like the Suzuki GSX series and Honda’s CBX models were being specified with four valve designs – 16 in total for a four-cylinder machine – but Yamaha went one better with a five valve design.
The 20 valve four cylinder engine was part of Yamaha’s ‘Genesis’ design concept, which was launched on the FZ750 of 1984. Multi valve designs worked on several levels. Not only did they allow more fuel into the cylinder, they also allowed for higher revs, because the individual valves themselves were smaller and lighter.
Genesis not only featured five valves per cylinder (three intake and two exhaust) but had the cylinders canted forward to allow the use of downdraft carburettors to feed more fuel into the motor.
The concept remained a feature of the Yamaha range for almost 20 years, even if other manufacturers didn’t buy into the idea of five valves per cylinder. The design made Yamaha’s racing R1s and M1 MotoGP bikes peaky and difficult to ride, and the concept was eventually killed off with the introduction of the 2007 YZF-R1.
While the ‘16v’ (16 valve) badge was proudly displayed on the back of every self-respecting boy racer’s hot hatch in the 1990s, in the 1980s ‘Turbo’ was the ultimate go-faster status symbol.
With all kinds of car getting the turbo treatment, motorcycle manufacturers sought to get in on the act too.
Between 1982 and 1984, all four Japanese manufacturers brought turbocharged bikes to market: Honda brought the CX500 Turbo, Yamaha boosted the XJ650, Suzuki came along with the ill-judged XN85 and even though Kawasaki’s GPz750 Turbo was the best of the breed, it remained a relative sales flop.
Behind the marketing headlines the bikes were complex, expensive and just not that good. As other, more conventional, technology (four valve heads, water-cooling and improved engine design) came through, turbos were quickly forgotten and never spoken of again.
Funny front ends
While mainstream manufacturers are constantly striving to improve their designs, 40 years ago it felt like many were trying to completely reinvent the wheel.
One of the flaws in the basic motorcycle design as we know it today has been the steering, braking and suspension functions are all carried out through the front forks. That means that under braking, the suspension compresses and cannot cope with bumps, while the geometry constantly changes under braking and acceleration.
The solution, said engineers, was to separate the functions. Hub centre steering systems appeared in racing in the 1980s, led by French petrochemicals giant, Elf, which had been experimenting with novel systems using steering pivots inside the front wheel hub, with a swingarm attached to the main frame.
The system was most famously used in 500cc Grand Prix racing, with British rider Ron Haslam gaining some respectable results in the mid-1980s.
Despite being lauded for its ability to brake late and hard, the systems were generally criticised for the lack of rider feedback. The 1990s saw Italian boutique bike builder Bimota introduced a similar system for its Tesi, while Yamaha’s GTS1000 was another notable hub centred machine.
Only BMW’s K-series models, which used a version of the system developed by Scot Gordon Hossack, persisted with an unconventional front end for any period of time. Called the ‘Telelever’ it used a wishbone to add structural stiffness, but used conventional looking telescopic forks rather than a single-sided hub steering set-up.
Taking a different approach to the same problem, anti-dive forks were another technology tried by all the Japanese manufacturers in the early 1980s.
All took a slightly different approach (along with their own catchy acronym) but the majority used a hydraulic system that closed a valve in a fork when the brake lever was operated, which would restrict the flow of oil in the forks and therefore stiffen it up under hard braking.
The technology wasn’t well received by many riders, who criticised the lack of feel. Many enthusiasts blanked off the system and the rapid development of standard forks meant the technology was quietly dropped.
That said, modern electronic suspension has reopened the ‘anti-dive’ subject in a modern way, while Aprilia has even filed patents recently for a mechanical anti-dive system which uses a rotating brake calliper in the way that Honda’s 1980s ‘TRAC’ system did.