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| When Honda introduced the CBX, this six-cylinder, 24-valve Superbike seemed to be the atomic cannon of motorcycling. So, you may ask, what has Honda done to refine this mega-bike as it enters the 1980s? There's a catalogue of detailed changes, which add up to a more pleasant and wieldy cannon that produces a smaller mushroom cloud. Think of it as the SALT version of the CBX. |
This new CBX, like the first one, immediately gives its rider two distinct impressions. Once moving in a straight line at anything faster than a walking pace, the CBX feels as if it sheds 150 of its 606 pounds. There's a second, more powerful, impression. The CBX has a unitary sense about it; that is, the motorcycle feels as though it's all of one piece, much like one of those very expensive German automobiles.
You might need a Mercedes-Benz budget if gasoline mileage is of any concern, because the CBX consumes fossil fuel at an amazing rate. The lowest mileage figure recorded by the six-cylinder was 24.2 mpg, a number that reflected some hard traveling on winding roads. The best mileage resulted when one staffer deliberately rode the CBX to get a high figure - 42.0 mpg. To do this, he had to ride in a way that made little or no use of the accelerator pump for the carburetors. The CBX isn't likely to strand you, however. Given its generous 5.3-gallon tank capacity, you'll have about 150 miles behind you at our 28 mpg average before you begin walking.
The original CBX's healthy appetite for gasoline was evident back in the good old days when the precious stuff was only 65 cents a gallon. Bucks-up gas mileage wasn't the CBX's only shortcoming. As introduced, the bike had plastic swingarm bushings, throw-away shock absorbers, and an aggravating lean spot that disrupted the flow of mid-range power and created the impression that the big-muscle CBX had weak knees in the midrange.
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As it turned out, the original six cylinder suffered from a lean hesitation, and
it had a torque curve that rose steadily to 6500 rpm and then sagged back at
7000 and 7500 rpm, only to rise again at 8000 rpm. You couldn't say that this
was a midrange sag, because these engine speeds are above mid-range in the
CBX. The new CBX gives you the impression that it has far more mid-range
than the first six-cylinder Honda, but what it actually has is less mid-range
power (2500 to 5500 rpm) and no lean-spot asthma. Its torque curve rises to a
peak at 6000 rpm and then trails off nicely with a slight bump at 7500 rpm.
The 1980 CBX makes less horsepower and less torque everywhere than its predecessor. Our initial seat-of-pants notion ("Wow, what mid-range this new one has got!") was rudely disabused when the bike confronted the hard reality of the drag strip. Our best elapsed time, purged from two separate sessions, was 12.16 seconds at 111.11 mph. Those numbers are a long way from those produced by our first test CBX. It had run a jaw-dropping 11.55 seconds at 117.49 mph. Nor was that one motorcycle singular in its performance. Magazine tests in the CBX's first year repeatedly turned up times solidly in elevens. The 1980 Super Sport is six-tenths of a second and 6.4 mph slower than our original unit because it simply makes less horsepower.
Our first CBX, tested in February 1978, made 85.56 horsepower on the Webco dyno; the 1980 bike generated a maximum 71.59 horsepower, down almost 14 horsepower. The peak-horsepower engine speed in both cases was 9000 rpm. Maximum torque? The first test CBX: 52.27 pounds-feet at 6500 rpm (and 52.25 at 6000 rpm). The downside difference amounts to slightly more than five pounds-feet.
Anywhere you look on the dyno sheets, the 1980 model comes up with the short figures. From 3000 to 5000 rpm the horsepower spread between the old and new CBX ranges from 5.12 horsepower (at 4500 rpm) to 1.74 horsepower (at 5000 rpm); on the torque side the differences run from 7.90 pounds-feet (at 3500 rpm) to 1.82 pounds-feet (at 5000 rpm). If the new bike gets almost even with the old one at 5000 rpm, the 1980 model loses ground to 7000 rpm, and then is steadily overwhelmed by the old Super Sport to 9500 rpm.
Honda slipped the CBX out of the elevens by way of Germany. Within the last year, the Germans have adopted a stone-hard horsepower ceiling: 100 at the crankshaft. If a motorcycle had more than that, it wasn't going to be imported for use on German public highways. Honda's claimed peak crankshaft horsepower was 103 for the first CBX, and so faced with the German limit and concerned with its spread to other European countries, the Japanese decided to tune down the CBX.
According to Honda, the crankshaft horsepower was backed down to 98, a loss of five off the top, or roughly a five per cent drop. Clearly, our 1980 test unit lost more than five per cent in terms of rear-wheel horsepower to its predecessor; the drop was 16 per cent.
Honda's American spokesmen have noted that CBX production is so small by Honda standards that it made no sense to produce separate models for the United States and other countries. Besides, though a horsepower ceiling was a German problem, emissions were an American one. The carburetors have been rejetted to help make it possible for the 1980 CBX to pass the 1981 emission tests. There's no real reason to believe, however, that jetting accounted for the new CBX's shortfall since more fundamental changes have been made.
Honda's hop-down efforts are seen in the 1980 CBX's low-lift cams, which open the intake valves 7.8 millimeters and the exhaust valves 7.0 mm. These lifts are .5mm less than before, and they clearly are less than the engine needs for maximum power. There may be some emission-control benefits with the reduced lift, but the deepest bow in the EPA's direction was made with revisions in valve timing. Specifically, by advancing the exhaust cams five degrees and thus closing the exhaust valves at TDC instead of leaving them open further into the intake cycle. This shortening of the "overlap" phase cuts the time during which fuel droplets can escape past the exhaust valve and become those unburned hydrocarbons our government finds so abhorrent. It also shortens the CBX's breath, which is a bonus or a curse depending on how you feel about the performance.
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