The term “superbike,” formerly used imprecisely to refer to motorbikes with 500–750cc engines, would acquire a distinct connotation as the 1980s and 1990s drew near. The way bikes are built and made has changed over the past 60 years due to advancements in technology, research, and manufacturing. Simple casting processes have evolved to almost forging perfection in motorcycle engines, from cast iron air-cooled cylinder engines to water-cooled electro-plated sleeveless ones.
Motorcycle manufacturers began experimenting with more significant and powerful engines around the middle of the 20th century. One of the first superbikes is commonly recognized as the BSA 1949 Gold Star ZB34, available in 350cc and 500cc single-cylinder, four-stroke displacements. Each hand-built motorbike, with a top speed of 110 mph, was accompanied by a dynamometer test report indicating its horsepower. But the superbike mania began with Honda’s 1969 CB750, which had several ground-breaking features.
As Japanese producers Kawasaki, Suzuki, and Yamaha entered the market, intense competition resulted. The early evolution of superbikes in India and globally persisted throughout the 1990s, marking the start of sophisticated electronics and other improvements that demonstrated the industry’s ongoing progress in engineering and technology.
The Sixties: 1969 Honda CB750
Many people considered Honda’s CB750, which debuted in 1969, the first superbike. Its 4-cylinder bike engine, disc brakes, four-into-four exhaust system, and electric starter—something never seen before—revolutionized the motorcycle business. It marked a dramatic change from the bulky, lumbering traditional American and British motorcycles. The CB750 was more dependable, lighter, and faster than its rivals.
It was an enormous success when it was first publicly displayed in October 1966 at the Tokyo Motor Show. Until today, Honda vehicles used a split-type, press-fit crankshaft lubricated by needle bearings. The four-cylinder CB750 made a unique switch from needle bearings to an integrated crank with simple bearings because of the integrated crank’s resistance to torsional twisting and engine friction. When it debuted in showrooms in January 1969, the air-cooled, 8-valve, SOHC CB750, which weighed 736.5cc and produced 67 horsepower at 8,000 rpm, was an instant smash.
The Seventies: 1973 Kawasaki Z1
When Honda Motorcycles debuted the CB750, Kawasaki wasn’t far behind in designing their four-cylinder motorcycle, the 750. This forced Kawasaki to abandon its intentions to build a SOHC 750 four and instead develop the more considerable, fabled 900 Z1 in 1972 after being beaten to the line.
Known internally as the T-103 and given the moniker “New York Steak” during its developmental phase, the Z1 retained roller bearings for its crankshaft but had cams that rotated within plain insert bearings, in contrast to the CB750, its competitor. Japanese manufacturers would not use simple steel bearings for their crankshafts until the mid-1970s. With a 903cc engine and 82 horsepower available, the Z1 might have been superior to the CB750, but its handling and braking were suspect at 506 pounds.
Even though it was deficient in this area, it was nevertheless the superbike to purchase and gained popularity immediately. It was unquestionably the quickest of a new generation of bikes that would lay the groundwork for liter-class Kawasakis in the next ten years, with 92 Nm of torque and a top speed of 131 kmph.
The Eighties: 1984 GPZ900R | 1985 GSX-R750 | 1988 Honda RC30
Eleven years after the Z1 was first introduced, 1984 was a significant year for Kawasaki because of the new standards they set with their motorbike lineup. Engineers at Kawasaki set out to build a new motorcycle in 1980 that would be just as deserving of being the Z1’s successor. Although it was overly broad and had two valves per cylinder on a transverse six, their prototype was an air-cooled DOHC engine that satisfied their design requirement for a powerful and smooth engine. Their second prototype was a counterbalanced, air-cooled, DOHC, 16-valve engine that produced excessive heat.
By the end of 1982, the solution included liquid cooling, which marked the beginning of all future superbikes. The intake camshaft was driven from the right side of the crankshaft, while the exhaust camshaft was moved from the left. When the GPZ900R went into production, it had a single camshaft cam chain powered by the engine’s left side to maintain its thin design.
Without computer analysis, test riders would relentlessly test the frame over hundreds of kilometers each day until one was found. The definition of a superbike was utterly upended when the GPZ900R was introduced. The bike was initially sold under the name GPz900R, then KMC came up with a more appropriate moniker that stuck: GPZ900R Ninja. It featured straight-cut primary drive gears, a balancer shaft, 38mm air-assisted forks with anti-dive characteristics, a one-piece forged crankcase with a jackshaft-operated alternator behind the cylinder bank and a uni-trak mono-shock absorber at the back.
It also featured wet cylinder liners. Even though it weighed 503 kg, its 115 horsepower at 8,500 rpm allowed it to reach 151 miles per hour and complete a quarter-mile in 11.18 seconds at 121.65 mph. Up until the middle of the 1990s, the GPz900r Ninja served as the model for all Kawasaki motorbikes and the standard for all superbikes.
Suzuki debuted the GSX-R750 in 1985. It was a race replica heavily modeled after Suzuki’s Works endurance motorbike, which had won the 24-hour World Endurance Championship at Le Mans. Constructed under the tagline ‘Born on the circuit, back to the circuit,’ the 750 was a street-legal, detuned version of the GS1000R, with all parts lightened to achieve higher revs. Its output was derived from a smaller mass without the complications of a water jacket; instead, Suzuki’s Advanced Cooling system was used for oil cooling. Almost all components were knifed to reduce weight further, and the magnesium rocker covers replaced the aluminum ones.
Because it was lighter than any competitor in the 750cc class, the 749cc high-performance two-wheeler—famously dubbed “slabby” due to its slab-sided stylistic features—had an advantage in power-to-weight ratio. According to the manufacturer, the Suzuki’s aluminum frame weighed only eighteen pounds, half as much as a steel counterpart. The motorcycle’s Mikuni flat-slide carburetors allowed it to reach speeds of over 7,000 rpm and over 100 horsepower at 10,500 rpm, sufficient to run 145 miles per hour. Although the Suzuki’s 18-inch front wheels made steering difficult, the design was inspired by factory endurance racers and made wheel replacement easier. Later, the racers would wear 16-inch rims; nevertheless, 17-inch rims soon followed.
Honda started looking into new strategies in the late 1970s to challenge Suzuki and Yamaha’s two-stroke dominance in racing. Soichiro Honda’s distaste for two-stroke engines made sense, of course. Due to its filth and pollution, motorcycles could only have 500cc and four cylinders when the racing regulations were changed. It would be challenging to defeat the two-strokes, but Honda also realized that their new vehicle would need to rev twice as high.
It resulted in the 1988 Honda VFR750R, which returned to racing after an 11-year break and was profoundly influenced by the oval-piston NR500. Based on the RVF750 Works motorbike, which had dominated the Formula One World Championship and endurance racing in the mid-1980s, the Honda RC30 was a limited-edition, homologation particular motorcycle designed exclusively for racing. Driven by a 748cc, V-4, gear-driven double overhead camshaft, the RC30 had a 360° big bang crank, just like the racers from RVF, and had a superior drive out of corners compared to the 180° 750F.
It was a lighter version of the Honda VFR750F with components made of exotic metals, such as titanium for the exhaust, intake, and conrods. It also featured a slipper clutch, Showa front forks that allowed the brake calipers to stay in place for quicker wheel changes, and a single-sided swingarm made by Elf. The French-built swingarm had an intriguing feature: the brake rotor was positioned within, with the chain and sprocket situated outside, and the wheel secured by a lone castle nut and cotter pin.
If it weren’t for the variations in the cylinder heads and engine side covers, the engines of the 750F and RC30 were nearly identical and hard to distinguish. With a redline of 12,500 rpm, it reached a maximum output of 112 horsepower at 11,000 rpm, an increase of more than 7 horsepower over the VFR750F. It operated smoothly at low revs and pulled through the gears. Fred Merkel of the United States and Carl Fogarty of the United Kingdom competed against the Factory Works motorcycles while riding outfitted RC30s. Merkel won the first World Superbike Championship in 1988 and again in 1989.
The Nineties: 1990 Kawasaki ZX-11 | 1992 CBR900RR | 1994 Ducati 916 | 1998 Yamaha YZF R1
The ZX series served as the foundation for the nineties and what we see now if the GPZ and GPX were the models of the eighties. Kawasaki was creating the groundwork for some powerful horsepower that would be released in the shape of the ZX-11 as the ZXR-750 raced on. The GPz900R served as the foundation for the ZX-11, which was essentially an evolution of the ZX-10 Tomcat, albeit there were few similarities between the two.
It was the first motorbike to employ the idea of ram air induction, an outdated American hot-rodder tactic to increase horsepower, with a 1052cc, liquid-cooled, DOHC, 16-valve engine. The idea was straightforward: the engine’s power also increased as the motorcycle’s speed increased. Massive volumes of air were forced through a single hole in the front fairing, passing through a snorkel and an air intake duct before arriving at an enormous airbox. Thanks to its aerodynamic bodywork, the ZX-11C model produced 147 horsepower at 10,500 rpm with ram-air assistance and was incredibly stable at its terminal velocity of 175 miles per hour. At 4,500 rpm, it had a distinctive flat spot similar to some carburetted superbikes, but after it passed it, it took off like crazy. Cycle Magazine demonstrated the ZX-11’s mettle by finishing a quarter-mile at 132.21 mph in 10.51 seconds.
With a new Y-type aluminum twin-beam frame from the previous model, Kawasaki updated the ZX-11 D model’s styling in 1993. The main changes were made to the upper fairing, where a twin ram air intake system routed from within the front of the frame led to a 20% larger airbox and new side panels that gave it a more upscale appearance. Although Kawasaki lost the speed championship to the Honda CBR1100XX Super BlackBird in 1996 by a few miles per hour, the company’s creation of the ZX-11 ensured that the motorbike would remain the best option for years.
In 1992, Honda unveiled the CBR900RR FireBlade, which completely changed the motorcycle business. Because of its 893cc displacement, the CBR900RR was not designed as a racing copy; however, throughout development, the German Autobahn, where some sections had no speed limit, served as the development environment. Honda created a motorcycle that could simultaneously accelerate from 0 to 60 miles per hour as a motorcycle in the liter class.
Ducati was preparing its project while the Japanese were engaged in a full-scale conflict. From the invention of the four-valve Ducati Desmoquattro engine, through the development and racing of the older Pantah versions to the road-going 851 and 888 models, the Ducati 916 is one of the most exquisite motorcycles to come out of Italy in 1994. Massimo Bordi created the V-twin engine, and Massimo Tamburini and his team at the Cagiva Research Centre in San Marino developed and styled the motorcycle. The water-cooled engine 916 was an upgrade over the Ducati 888, with a more significant displacement and a new engine control system.
With its single-sided swingarm, 43 mm Showa upside-down front forks, and trellis frame, the 916 cc liquid-cooled, 4-valve Desmodromic, 90° V-twin engine was a masterpiece. The motorcycle was sleek and slender, with a wonderfully designed fairing that extended from the front through the tank and ended at the tail. The 916’s excellent handling on various uneven road surfaces and its attractive appearance are a credit to Showa’s suspension, and the amount of research and engineering the Japanese had put into the vehicle.
The Japanese motorcycle industry would take six years to produce a really exceptional machine. When Yamaha initially decided to develop the YZF-R1, the chassis was built first, and the displacement was agreed upon later. The engine of the Genesis 5 was potent. The four-cylinder engine with a displacement of 998cc, 20 valves, and an 11.8:1 compression ratio generated a wide power range with a maximum output of 150 horsepower at 11,750 rpm. The 1998 Yamaha R1’s remarkable engineering made it the lightest and most compact motorcycle ever produced, weighing only 390 pounds. The engine served as a stressed member alongside the Delta Box structure that didn’t need to be unduly strong because it had a one-piece cylinder and crankcase, which made it stiffer than most conventional engine designs. As a result, the motorcycle had a lower weight than some 600cc bikes models.
Yamaha elevated the gearbox input shaft on the engine side so that the gearbox output shaft could be positioned underneath it. Other manufacturers adopted this “stacked gearbox” design, resulting in a small engine and a 1,385 mm wheelbase with an optimized center of gravity. Fuel was supplied to the engine via four 40 mm Keihin CV carburetors; fuel-injected versions weren’t produced until the third generation. Motorcycle Consumer News tested the 1998 model year YZF-R1, and the results showed a 2.96-second 0 to 60 mph pace and a 10.19-second 1/4 mile time at 131.40 mph.
While the 1980s set the stage for the development of motorcycles in the 1990s, the Honda CB750, widely regarded as the first superbike, is mainly responsible for the rapid advancement in computer technology that occurred in the new millennium. This led to the development of motorcycle design and engineering.
