2020-01-23 CBX Retrospective by Clement Salvadori

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This retrospective look at the Honda CBX appeared in Rider magazine's October 1996 issue. 

 

When Honda pulled the wraps off the CBX late in 1977 the moto-world was mildly bemused and immensely impressed. Bemusement came from the six-pack of cylinders and two dozen valves, impression from the colossal power. There were 85 honest horses at the rear wheel (the only place they really count), prompting a quarter mile in 11.5 seconds with a speed approaching 120 mph. Wow!

Round two of the Horsepower Wars had recently begun. Round one had been a long one, beginning with the H-D Sportster in 1957 and ending with the Kawasaki Z-1 in 1973. The Americans and Europeans had dropped out, and it was strictly intra-Nipponese battling. In anticipation the four manufacturers had been working away in their secret labs long before the four apocalyptic motorcycles met in the winters of '77 and '78.

Kawasaki fired the first shot of Horsepower War II, so to speak, with the KZ1000. That company knew the competition was going to be ferocious, but had taken the lazy-man's approach. Building upon the highly successful KZ900, they bored the engine out to 1,015cc, did a few motor and chassis mods, and sat back to see what the other three would do. Then came Yamaha's stump-pulling XS1100 and the agile Suzuki's GS1000 -- variations on the DOHC, eight-valve, in-line fours. But the CBX1000 (in reality, 1,047cc) was another mind-blowing innovation from Honda R&D. This corporation had knocked the the rather complacent motorcycling world back on the heels of its Bates boots with the CB750 back in 1969, and now it was doing it again. Bigger, better ... and a lot more complicated.

An in-line six was not a new idea, since Benelli had brought out its 750 Sei version in 1975, with SOHC and three twin-throated Dell'Orto carbs. And Benelli's connection with Honda was well-known ... but what the Italians could do, the Japanese could do better.

Much had to do with the fellow who led the development of the CBX engine, Shoichiro Irimajiri. As a young designer with Honda in the '60s, he was instrumental in building the 250 GP bike -- the one with six cylinders set across the frame. If you can win races with this kind of engine, why not quadruple the size and win a big portion of the street market?

It was a superb piece of engineering. Irimajiri kept the DOHC engine as narrow as possible, utilizing power takeoffs from the middle of the crank. A centrally located Hy-Vo chain ran the exhaust camshaft, and another Hy-Vo ran from exhaust to intake cam. An industrial-strength Hy-Vo served as primary drive, while a jack-shaft powered all necessary secondary components, like the alternator. Engine width was only two inches more than that of the CB750.

Six 28mm Keihin carbs bolted to the head. Small valves, 24 of them, went up and down at a dizzying 9,000 rpm, which was about a thousand revs more than the competition. Irimajiri's idea was that small oversquare (64.5mm bore by 53.4mm stroke) cylinders and a light valve train would be the key to rpm and subsequent horsepower.

The engine was hung from a backbone frame, with the cylinders inclined forward to give the rider knee room. Looking at the CBX from a frontal vantage point gave the viewer an idea that the rest of the bike was merely there to frame the engine. The whole package was attractive, but the motor overpowered the machine.

Wheelbase was almost 59 inches, an acceptable distance between axles for a bike that boasted sporting pretensions. By the time the tank was filled with four gallons of fuel, the weight was up to 600 pounds, which was enough to test the adhesion of the tires when charging around at full tilt. But the CBX did handle well, with conventional twin-shock swingarm and 35mm fork tubes. As a matter of fact, it did everything well ... except sell.

Somehow it did not strike a chord in the hearts of motorcyclists. Everyone admired it, everybody wanted to ride it, but few people were buying it.

Honda, not wanting to abandon all this developmental work on the CBX, spent some more money turning the twin-shock rear end into a single shock Pro-Link system, fattened the fork tubes to 39mm and altered the rake, extending the wheelbase by an inch and a half. New camshafts shifted the power curve slightly, a little more midrange, a couple less ponies at the top end. A larger five-gallon gas tank was designed, and Hondaline accessories bolted on a good-looking fairing and rather small saddlebags -- sport touring, following the European lead of the BMW RS and Moto Guzzi SP, was coming to Honda.

But all for naught; the CBX, even in the 1981 touring guise, just wasn't going places. Later that year Honda introduced the CB900, with four cylinders and four valves per combustion chamber; perhaps if Honda had done that in 1977, motorcycling history would have been substantially different.   -- Clement Salvadori

For those with an interest in the CBX, the International CBX Owners Association will keep you in spare parts and useful tips. Contact Clint Hooper, ICOA, 1603 City View, Wichita Falls, Texas 76305, for particulars.