When it was introduced in 1982, the CX500 Turbo was, and still is, one of the most futuristic motorcycles ever made. Unfortunately, the CX500 Turbo was only made for one year. The Honda CX500 Turbo was the world’s first production turbocharged motorcycle. It was also the first Honda motorcycle to feature electronic fuel injection. The machine featured turbocharging and programmed fuel injection--both computer controlled. The engine also had electronic ignition. The futuristic style was designed by Italian stylist Giovanni Michelotti.
The 51 mm IHI turbocharger provided approximately 19 psi of boost--nearly doubling the engine’s output in non-turbo form (50 hp). To accept the extra power, the engine case was modified to accept larger crankshaft bearings. The suspension, fairing, and brakes also differed significantly from the earlier CX500 the Turbo was based on. The Turbo bike featured the Pro-Link rear suspension and the TRAC (Torque Reactive Anti-dive Control) front suspension.
The CX Turbo was not happenstance, but a direct response to factors shaping the market in the early 1980s. Yamaha was battling Honda for supremacy in the motorcycle market, and Honda was fighting back. Honda management decided to show the world that their company was capable of a design and engineering feat that was far ahead of what any rivals could do. That showpiece was the CX500 Turbo.
Normally, Honda exhibited new motorcycles to the press only when the development work had been completed and the bike was almost ready for sale. Although nowhere near ready for the market, Honda put the CX500 Turbo on display at the 1980 Cologne International Motorcycle Show, and later had it on exhibit at the Honda Research and Development Center in Tokyo.
Honda claimed 82 horsepower @ 8,000 rpm and 59 lb-ft at 5000 rpm from the 7.2:1 compression ratio 495 cc engine. The Turbo could attain a top speed of 128 miles per hour. The machine was capable of a quarter-mile time of 12.3 seconds at 106 mph. Not bad for a bike that weighed 571 pounds.
Honda produced more than 230 patents for the components on the CX500 Turbo during development. The turbocharger was mounted in front of the engine to take advantage of space as well as additional cooling. The front fender had small scoops to direct more cooling air to the engine.
Riders found the bike exhilarating on acceleration from 4000 rpm and above, but the engine suffered from turbo-lag at lower speeds. The bike was very “peaky,” either suffering from turbo-lag or blasting ahead aggressively, making the machine a handful on a road course. On an open stretch of road, the bike was great fun!
The Turbo bikes did not sell well. Only 5400 were sold; roughly 2000 remain today. By 1986, Kawasaki was the only manufacturer still building a turbocharged motorcycle.
A turbocharger is used on an internal combustion engine to provide more power, typically at higher rpms. Exhaust gases rushing out of the engine under pressure spin a turbine, which spins a compressor, which in turn compresses the intake air charge over atmospheric pressure providing more air and fuel to the engine..
In motorcycling, the turbo concept began with experiments by race teams looking to get more combustible mixture into engines faster. Most of the GP race teams of the Thirties tried supercharging, a different means to reach the same result. In the 1970s, drag racers installed turbo kits on their motorcycles, and automobile manufacturers began to research turbocharging as a way to get extra performance out of the small engines being produced during the “fuel crisis.” Turbo kits began to migrate to street motorcycles, and in 1978, Kawasaki America came out with a limited production turbo, the Z1R-TC.
The basis of the CX Turbo was the CX500. Powered by a V-twin that was often criticized for looking like it came on an air compressor, the CX500 was the sort of bike you bought to get to work every day, no matter the conditions. The bike was reliable, just not very exciting. As a platform for innovation, however, the CX500 had potential. It had liquid cooling, shaft drive, and mag wheels. The first V-twin ever built by Honda, it had four valves per cylinder, fed by constant velocity carburetors. The 1981 version of this bike had Honda’s innovative Pro-Link monoshock rear suspension, which moved weight under the rider and featured more progressive damping.
Honda took the CX and re-engineered it into the Turbo. Reasons for choosing this bike as the platform for turbocharging included its liquid cooling, which enabled the engine to cope with the increased heat of turbocharging. Another was displacement — midsized bikes had quite a following in the late Seventies.
According to Kazuo Inoue, Honda’s top man in R&D at the time, the project was made more difficult by the CX’s V-twin configuration and its smaller displacement. But Honda was able to make the CX500 Turbo work despite difficulties and produced more than 230 patents for components in the process. The turbocharger was built to Honda’s specifications by IHI. Honda mounted it in front of the engine to take advantage of available space and additional air-cooling. It was one of the first production bikes to feature computer-controlled fuel injection.
The front fender employed small scoops to direct more cooling air to the engine, while air-assisted front forks and dual front discs, each with twin-piston calipers, took care of the stopping power. The front end used Honda’s innovative TRAC (Torque Reactive Anti-dive Control) anti-dive system, which linked the brakes to the fork valving. As the brakes were applied, the calipers pivoted, pressing on fork valves to restrict compression damping. The wheels featured the ComStar rib pattern, with a wind tunnel-tested fairing adorning the bike.
With at least 5 large “Turbo” graphics on the bike, it’s clear Honda was making a statement graphically as well. Outside the US, the Australian and the Japanese home markets got a fairing with a large red ‘OBRUT’ backwards-writing graphic. All the better to let those cagers in front know what was approaching from behind.
Basically, air was routed from the front of the CX though an oiled foam air filter and then into the compressor portion of the turbocharger. From the turbo mounted in front of the engine, air traveled to a plastic box (called a surge tank), and then through reed valves and intake tubes into the cylinder head. Fuel passed through a fuel filter before being pushed under pressure by an electric fuel pump, where it was fed to fuel injectors that released a precisely calibrated flow of fuel to the intake tubes. The whole operation was controlled by a mini computer in the tailpiece, which got continuous feedback from multiple sensors. Fail-safe systems were built into the computer so that even if several sensors failed, the bike would run well enough to make the trip to the dealership.
After more than a year of allowing the public view the project, the CX500 Turbo finally arrived at dealerships in the spring of 1982. Several motorcycle magazines, Cycle World, Road Rider, and Cycle tested the bike and offered similar reviews. Most reviewers agreed the bike was a comfortable and reliable sport tourer. The fairing worked well and the riding position was comfortable. Vibration was low and controls, except for a somewhat heavy shift lever, were easy to operate. The boost came in at about 4,000 rpm and proved to be exciting. Reviewers also noted the bike’s considerable weight, poor low-speed handling, a lack of low-end power, and difficulty controlling the motorcycle when the boost came on so strong. Others noted high fuel consumption and a lack of a fuel reserve. The turbo bikes were a sometimes scary Jekyll-and Hyde affair – slogging one moment and scalding acceleration the next. But that boost was pure, grin-producing, and shoulder-wrenching fun!
Time of change
A steep recession took hold from July 1981 through November 1982, and the bottom dropped out of the motorcycle market. Honda and Yamaha had been exporting lots of bikes to the U.S., and to get unsold inventory out of warehouses, both were selling motorcycles for rock bottom prices. Threatened in the market, Harley-Davidson petitioned the International Trade Commission for relief, resulting in the ITC imposing tariffs on 700cc or larger Japanese motorcycles.
Despite the gloomy economic outlook, Yamaha introduced its own Turbo shortly after the launch of Honda’s Turbo. Kawasaki and Suzuki were not far behind with their own offerings, with the KZ750 Turbo and XN85D, respectively, introduced for 1983.
For 1983, Honda punched out the CX Turbo from 497 cc to 674 cc and raised the compression ratio somewhat (7.8:1 versus 7.2:1) for an increase in horsepower from a claimed 82 to 100. It would prove to be the end of the CX Turbo. 1983 was basically the end of the road for the turbo wars. The motorcycle market was not improving, and Honda, Yamaha, and Suzuki dropped their turbos, with only Kawasaki holding out, producing their turbo until 1986.
1982 Honda CX500TC General Specifications
Claimed power: 82 hp @ 8,000 rpm
Top Speed: 121 mph (period test); claimed 128 mph
Engine: 497 cc liquid-cooled OHV 80-degree V-twin, 78 mm x 52 mm bore and stroke, 7.1:1 compression ratio
Weight (w/half tank fuel): 571 lb
Fuel capacity/MPG: 5.3 gal / 35-50 mpg
Price when new: $4,898