1979 Honda CBX Road Test - page 3

Immediately Otsuka realized that the bike needed more between-the-knees room for the rider. From that came two significant engineering decisions: to tilt the engine forward in the chassis 33 degrees, and to mount the carburetors on V-shaped manifolding so that all six of them angle in towards the centerline of the motorcycle.

Achieving a satisfactorily narrow knee-to-knee dimension was but a single subcategory of the major engineering and styling problem, "Engine Width." At the very heart of the solution is what Irimajiri identifies as his favorite component: the jackshaft. He likes it because it made the six-cylinder engine a feasibility; he likes it because it posed a very difficult design problem in that so many forces act on it; he likes it because it has to do so many things. The jackshaft is turned by a 34mm-wide Hy-Vo chain driven by a sprocket machined in the middle of the crank. One end of it drives the alternator. The other end times the ignition, accommodates the starter motor gear and carries power from the crankshaft to the clutch housing, which in turn spins the oil pump through sprockets and chain. Conventionally, both the alternator and the ignition system are driven directly off the end of the crankshaft; this is true of all modern multicylinder motorcycle engines. But because the CBX is a high-performance sporting bike in need of cornering clearance commensurate with its character, and because six cylinders all in a row occupy a large and irreducible amount of transverse territory, to hang the alternator and the ignition on the ends of an already broad crankcase assembly was unacceptable. From end to end, the CBX engine measures 23.4 inches - only two inches more than the CB750. The jackshaft makes this possible. That's why Irimajiri feels such a warm affection for it.

In nearly every case the race track is the enemy of the street bike. A race track is not a road. It has been designed for one purpose: to cause separations and create gaps between riders and between motorcycles, and thus to convert a random assortment of competitors on the start line into a carefully ordered procession of truth at the finish. The track provides an opportunity for the rider to spelunk on down to the dim-lit basement of his motorcycle, where its character is kept. Motorcycles built for racing-TZ750 Yamahas, RG500 Suzukis-maintain coherent dialogues with the track. Street motorcycles as a rule do not, the track asking many questions they have not been engineered to answer.

Still, the basement is the basement, Willow is Willow, and this is where the CBX has been brought. Two immediate realities present themselves: the CBX's speed is disguised by its smoothness and its buttery spread of engine torque; and while its high-speed handling is certainly acceptable considering what it is (a street bike) and where it is (a race track), it has been incompletely developed.

Climbing on the bike for the first time, the journalists were awed by the bulk below and in front of them. Its cistern of an engine in no way intrudes into the rider's space, but parts of it seem always to be in the line of sight. And any impression of the fuel tank as a tight-skinned sculpturing vanishes when the tank is viewed from the saddle. From there it takes on a rounded, flowing voluptuousness made necessary by the bridgework beneath it. The seat is comfortable, and close to the ground. The handlebars, a pair of black aluminum forgings clipped to the tops of the fork pipes and drilled for lightness, are exactly where they ought to be - and can be adjusted if they're not. The fuel tank filler apparatus reflects stylist Otsuka's quest for the appearance of function: it's large, finished in black, and is secured not only by its own threads but by a polished hasp which swings down across its top and locks in place. This mechanism is derivative of nothing, but evocative of performance and efficiency. Below the instruments, a voltmeter; below that, a pod where idiot lights are displayed; and below that, mounted on the top triple clamp, is a covered fuse box.

The bike's rear springs were immediately adjusted to maximum preload, the engine was brought to an acceptable temperature by the attending technicians, and the high-speed laps began.

   

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