Honda CBX 1000 Pro-Link

Honda reconfigured the CBX for 1981 as a sports touring bike, with fairing and saddlebags. The rear suspension also changed from dual to mono shock, and saw the introduction of the progressive linkage system - hence the name Pro-Link. The mono shock was attached at the bottom to moveable linkage instead of directly to the swingarm, changing it from a fixed to a variable ratio of shock absorber / rear wheel movement.

In Europe the CBX1000 went through the only major specification change of its four year life span with the introduction of the CBX1000B (from engine number SC03E2301512 and frame number SC06-230065). From pure sports, it now devolved into a sports/tourer. Cosmetically the CBX1000B gained a full fairing with storage pockets, engine protection bars and a 54lb weight gain. The brakes were upgraded to help stop the extra bulk, now featuring ventilated discs with twin piston calipers.

The suspension was changed dramatically with the front forks being increased to 39 mm, with the rear suspension now sporting Honda's mono shock 'Pro-link' system and an aluminum swinging arm. This had the knock-on effect of increasing the wheelbase from 58 in to 60 in. Internally the motor was in the same state of de-tune as the American models, with output being a claimed 100 bhp at 9000 rpm. Other changes included adjustable handlebars, an adjuster for headlight level, together with the option of hard panniers. The bike was finished in a dark silver grey with reversed black Comstar wheels

Review

LIFE HAS ITS SURPRISES. HONDA'S CBX was fashioned in the image of an illustrious family of GP racing machines, made to stand as their surrogate among the muffled and headlighted, hailed as the ultimate in Super Sport motorcycles. But it proved to be just too much of the wrong kind of bike for the Super Sport game. It needed help and we were sure that help would be forthcoming. What we didn't expect was that the mighty six-cylinder Honda would be reborn as a sports-tourer, saddlebags and all. Even less did we anticipate that the born-again CBX would be more successful in its 1981 Grand Luxe role than it ever was trying to be a street-legal GP device.

Honda actually had scant choice but to do what was done with the CBX. This flashiest of all Hondas got off to a lame start in 1978 and never gained the acceptance it deserved. Cycle's February '78 report told the world there was a CBX, but early problems delayed deliveries to dealers until late that year -- by which time many potential CBX customers were riding the then-new Yamaha XS1100s and Suzuki GS1000s. Then came our report that the refined '80 CBX was slower than the original. It wasn’t -- after an ignition-advance mistake had been corrected -- but the bike continued to sell like cold-cakes. And it became clear that the CBX probably never would capture hordes of buyers' hearts and wallets, So, Honda couldn't justify a mega-yen effort to make the 600-plus pound CBX float like a butterfly and sting like a bee; they might succeed but not without raising the Six's price prohibitively high.

Facing facts, Honda decided that if the CBX wasn't going to be the world's fastest motorcycle then it should be the nicest. Let others contend for the fastest-quickest-nicest honors; the CBX would be transformed into a luxurious sportstourer, a faster and better-handling alternative to the big GL1100 Interstate. A fraction of Honda's CBX-update money would go for engine work; the bulk was budgeted for chassis and luxury-accessory development.

Too much money spent on the CBX's engine would have been money wasted. It's no secret that this magnificently smooth and elaborate 24-valve Six is markedly short-winded. You'd expect the CBX to make big power and it can, but fleetingly. Then the temperature of its closely packed parts rises and the output drops. That tended to remove from consideration all dreams of a hyper-horsepower CBX, which would only have faded faster and lost reliability. And in some parts of the world motorcycles having more than 100 horsepower are prohibited. Earlier CBX engines would flash about 103 at their cranks (we are told), which meant Honda had a second reason for shaving off power at peak revs and adding it down at lower engine speeds-which is what was done to the CBX for 1981.

Most of the power-curve reshaping seems to have been accomplished by giving the CBX a new set of camshafts. These close the intake valves five degrees earlier than before, and retard both the opening and closing of the exhaust valves by five degrees. Intake lift is up 0.2-millimeters, to 8.0mm; the exhaust from 7.0mm to 7.5mm. The cams' profiles also have been revised to reduce tappet noise, and the '81 CBX is quieter than first or second editions of Honda's Six even with the fairing beaming noise at its rider's ears.

Subtle exhaust system changes are included in the 1981 CBX package and these, too, are said to nudge midrange power upward. There's an exhaust cross-over just upstream from the bike's twin mufflers, and we are informed that the individual pipes terminate at different lengths inside the collectors. Presumably they have done this so that instead of hitting exhaust resonance together the cylinders come "on the pipe" in pairs at different engine speeds. This, too, spreads power range at the expense of the engine's power peak.

Into the factory phone booth went the CBX, wearing its Superman vestments. Then out it came as a marathon runner dressed in After Six apparel. The ultra-high-performance crowd may be unhappy with the transformation. Others will be delighted: Who liked Superman anyway?

No changes in the CBX's transmission have been made-all the ratios are exactly as before-but the shock absorbing medium in the clutch hub is now coil springs. Earlier CBXs had rubber-loaded clutch hubs, which were fine until age and exposure to hot oil converted the rubber from elasticity to malleability. The coil springs probably won't be quite as good as new rubber; they'll be considerably superior to the solidified article.

Honda wanted the revitalized CBX to be the equal of its toughest competitor with respect to handling. It should come as no surprise that Suzuki's GS1100 was selected as the target bike, nor that Honda should resort to modestly heroic measures in an effort to make the CBX as good.

One thing Honda did was to revise the CBX's steering geometry and its fork very extensively. They re-angled the frame's steering head to provide 29.5 degrees of rake, two more than before, and then made up fork bridges with more forward offset to hold the trail at 120mm (4.72 inches). The new bridges also space the fork tubes 10mm farther apart, on centers, which is necessary because the tubes' diameter has been increased to 39mm. We always thought, and said, that the earlier CBX's 35mm fork tubes were too skinny for its weight and overall performance; the new ones aren't.

The CBX fork sliders have been enlarged to take the larger tubes, but are otherwise much as before-featuring fixed damping and Honda's excellent near-stictionless Syntallic bushings. As in 1980 the CBX fork is air-pressurized, at 10 pounds per square inch (plus or minus three psi, depending on preference), but it now has a balance tube connecting the two, fork caps and a single air fitting. Air pressure fine-tunes the fork, which also has a pair of light triple-rate coil springs installed in its tubes.

You may see "Pro-Link" used in advertising descriptions of the CBX's rear suspension and assume that it is the same layout as the one Honda employs for motocross. It isn't. There wasn't room for a large single shock standing above the CBX's swing arm, as space in that direction is occupied by a battery and other electrical components. So Honda lowered the shock and hooked it to the swing arm with a completely different system of links. Only the Pro-Link name is the same, which is fair because even though the parts are different the principle is not: it's a rising-rate suspension. The ratio between axle travel and shock compression is 2.78:1 when the CBX's rear suspension is fully extended; it becomes 1.92:1 at full bump.

 Leverage makes the CBX rear suspension progressively stiffer as it jounces upward, and it is made more progressive by its primary reliance on air as a spring. There is a coil spring built into the shock but it's there only as backup, to keep the suspension from collapsing down against its stops in the event that pressure should be lost. In fact, the relative importance of steel and air in this case is revealed by the existence of a pressure sensor and warning light. The shock is supposed to be pressurized between 28 and 57 psi, and if a leak drops it below the lower figure a panel light goes bright red. You are then instructed to reduce speed and seek out the nearest service station.

With the progressive action of the rear suspension's linkage creating progressive damping, Honda probably did not need to provide an adjustment. But they did, with three settings, which are selected by moving a push-pull knob located a few inches above the right-side footpeg. Pushed all the way in, the knob moves (via a clevis and rod) the damper valving to its softest rebound setting; fully out is fully hard, and anybody who can't tell the difference has totally numb hindquarters.

Now that nearly all high-performance motorcycles have triple disc brakes, two in front and one at the rear, Honda could give the CBX distinction only by doing something difficult. That's what they did, creating for the occasion a brake rotor of such intricacy that few manufacturers would attempt to make its equal. Rather than drill the expected pattern of holes through the sides of an otherwise solid disc, Honda cast (in stainless alloy) a rotor much like those fitted on large cars. That is, Honda cast in ventilating holes leading from the rotor's hub to its perimeter. It is a dazzling display of mastery of the foundry arts and admirable even if it actually accomplishes little more than all the drilled holes.

Only the CBX's two front brake rotors are radially vented; the single rear-wheel disc is solid. But the same twin-piston calipers Honda introduced last year are fitted front and rear, which is nice. The calipers use paired tandem pistons to apply braking pressure more evenly over longer, narrower pads, and are said to behave much better when wet for that reason alone. We know that Honda's tandem-piston calipers work well in the wet, and they also seem superior in rigidity.

There's a distinctly European flair to the new CBX's fairing, which is lower and narrower than those we are accustomed to seeing. The flair is understandable, if you know that the same fairing is fitted on Honda's European CB1100R. But the concept seems oddly abbreviated, trimmed, truncated, as though persons outside the styling department had been given jurisdiction over its final form. And that is exactly the case: Styling was allowed to propose, but the right of final disposition rested with Honda's wind-tunnel staff. Aerodynamic considerations decided the size and shape of the fairing, and even the saddlebags. Not because wind resistance was thought to be of paramount importance but because aerodynamics have a large influence upon high-speed stability. Big, blunt fairings and bulky saddlebags can provoke horrendous speed wobbles, and Honda thought it inappropriate that a genuine sports-touring motorcycle should have to operate under any speed constraints.

 The CBX's fairing seems totally successful in terms of high-speed stability. We ran our test bike up to a tachometer reading in fifth gear equal to 120 miles per hour and it was completely steady at that speed-which we feel is near the new CBX's absolute top speed. You might be able to upset the bike's stability by stuffing its saddlebags with lead ingots, thus shifting its center of gravity considerably rearward, but we believe that in any normal operating mode it would remain stable. With respect to weather and bug protection the CBX's fairing is only mostly successful. It does shield your body, legs and upper arms very effectively. The narrow side skirts may look skimpy, but they serve only to extend the protection afforded by the engine's wide cylinder block; your legs definitely are in out of the breeze. But the '81 CBX does nothing more to shield its rider's hands than last year's unfaired model. And the windscreen is too low to serve as a face and eye protector; a CBX rider will need a face shield or goggles.

 According to our contact at Honda, the CBXs bound for Europe will get tinted windshields; those on American models will be clear. Our test bike had a tinted screen, which makes us wonder, but this is a point of small consequence because you look over the windshield rather than through it. If there is to be a change, we'd prefer that it involve shape, not color, as the CBX's windshield sends a streamer of highly turbulent air back to buffet its rider's head. The buffeting is noisy, and at times it snatches a rider's helmet around like a giant hand. All of our test riders hated the turbulence. The only difference of opinion about it was that some of us felt we could become accustomed to it; others did not.

Everyone here at Cycle especially regretted the buffeting because in every other way the CBX does a lot to keep its rider comfortable and in control. It gives a seat/handlebar/footpeg spatial relationship that's near-perfect. Tall riders can be comfortable on the CBX; so can the short guys. They've even provided the means by which your riding position can be finely adjusted: The CBX has individual right and left handlebars clamped to the fork tubes’ extended upper ends. If you don't like the reach provided by the bars you can simply loosen their clamps and move them to where they feel better.

Elsewhere, Honda managed one comfort-related triumph and one flop. You'd have to rate the job done with the fuel tank as a victory of shape over capacity: The CBX's tank holds nearly six gallons of fuel, yet its contoured sides fit comfortably against your knees and thighs. Some people may feel that the tank is too broad to look right, but it isn't quite broad .enough to reach the cylinder head's ends, and in any case the bike needs all the fuel that can comfortably be provided. Gentle highway cruising may get you about 43 miles per gallon; slightly more brisk travel will pull the CBX right down into the 36-38 mpg range, and we got one hard-flog reading at 24 mpg. You wouldn't want a smaller tank.

Where the CBX conspicuously failed to please in long-duration rides was with its seat. This seat isn't as bad as the old Kawasaki Z1 Vinyl Crucifix, being much softer, but it does have the same deficiencies of shape. Honda has made the forward part of the seat sharply crowned, to give the CBX rider's legs a shorter reach to the ground. Our test riders, even the short ones, said they'd prefer a broader, flatter seat-which might not be as convenient at stoplights but would be less numbing.

At any temperature that invites riding, the CBX starts readily. You thumb the handlebar-mounted lever forward, hit the starter button, and the engine runs. No muss, fuss, or bother. The CBX needs only a minute of running before it's ready to go without the choke, and it keeps running almost as though the EPA had never heard of motorcycles. There is a softness in throttle response right in the 5060 mph range, in fifth gear, but under most conditions the CBX's accelerator pump compensates for its lean jetting.

CBX owners should hold themselves above contests of speed with Yamaha, Suzuki and Kawasaki Superbikes, maintaining in the face of challenges a cool aristocratic hauteur. They must hold themselves aloof because for all the CBX's lustrous looks and impressive specifications it's not a match for, say, a Suzuki GS1100. Our test CBX ran wonderfully consistent quarter-mile sprints, but it ran them a half-second and six mph slower than the original version we tested late in 1977. Still, you couldn't say that a motorcycle capable of running the standing-start quarter in 12.02-seconds at 111.52 mph is actually slow. And the number of showroom-stock full dressers able to run with the Honda CBX can be counted on the fingers of one foot.

This newest CBX has, as previously noted, very fancy front brake rotors. These have a diameter of 296mm, which is 20mm larger than last year's solid discs and about 50mm more than seems necessary. Maybe the big rotors are Honda's equivalent of power brakes. Anyway, they work well, though the front brake impressed us as being a little less solid-feeling than the last tandem-piston Honda brake we tried. One of our test bike's front discs had a dreadful squeal when lightly applied, but the brakes were effective even when literally smoking hot; and if the brake feel was slightly less good than Honda's best then it still was better than almost anything else.

Honda's dual front brake did not cause the unsprung-weight-related wheel hop we've discovered in some of its rivals. Perhaps this is because the forged-aluminum Honda ComStar wheels are themselves a lot lighter than those stylish cast "mag" wheels you see everywhere these days. In truth, they are aluminum castings, not ultra-light magnesium. Honda representative Jon Row, who takes such things seriously, says scornfully of the cast wheels, "They should be calling them 'als,' not 'mags.' "

 For 1981 the CBX gets another broadening of rim widths. The 19-inch front rim is now 2.50 inches across instead of the original 2.15; the rear rim, which first had a 2.15-inch width and widened to 2.50 in 1980, is now a 2.75 x 18. Both front and rear tires are V-rated Dunlop Gold Seals, safe at sustained speeds above 130 mph. As before, the CBX's front rim is fitted with a 3.50-19 tire. But the extra-wide rear rim now carries an extra-wide tire: a 130/90-18, which would be about a 5.00-18 if they'd labeled it in inches, and it actually measures 5.175 in. across its tread.

With its longer aluminum Pro-Link swing arm and increased 29.5-degree fork rake, the CBX has acquired a couple of extra inches of wheelbase, stretching it to 1535mm, or 60.43 in. This unusually long wheelbase and the strongly raked steering geometry should make the CBX slow-handling, a truck in traffic and a muscle-builder on fast curving roads. Further, the extra-wide rear tire should give the CBX a tendency to stand up in corners, requiring its rider to apply correction either as handlebar pressure or by shifting sideways on the seat like Kenny Roberts. In reality, the CBX has none of these characteristics.

Specifications notwithstanding, the CBX has totally neutral handling, and steering that is surprisingly light for such a heavy motorcycle. The bike is no joy in the confines of a crowded parking lot, as it has a lot of its weight invested in high places (the cylinder head, for example), and when it starts tipping you must either catch it fast or catch it firmly. But if you're rolling fast enough to bring the speedo needle off its peg, the CBX behaves very well, responding to commands without any show of reluctance. Its steering isn't light in the absolute sense; it isn't as heavy as that of some motorcycles the CBX outweighs by a hundred or more pounds. And the CBX also has a light, easily controlled clutch, excellent brakes and light, positive shifting to help its traffic manners. You can even get it shifted into neutral without a struggle. Our test bike's transmission would slip into neutral every time at the nudge of its lever.

marvelously sporting ride. We don't think it handles quite as well as the GS1100, but it's worlds better than anything else carrying saddlebags. The Honda's considerable weight seems perfectly distributed for rapid curved-roads travel, and for any given steering input you get the same response every time. It also has a marvelously steady way of coping with bumpy corners. Crank the CBX over, establish an arc, and that's how it goes until you issue other instructions. You get no nervous foot-shuffling and no unrequested course changes. If you keep the pace below a 50-percent (of peg-dragging, tire-sliding racing) effort, you won't even have to move the rear shock's damping-adjustment knob from its softest position.

For riding much above the 50-percent level you'll want to pull that rear suspension damping knob fully out. We know the knob only controls the rear shock's rebound damping, but pulling it feels as if there's slack taken in all over the chassis. With the knob pulled, the fork pumped up to its highest recommended pressure and the rear shock pressurized at 42 psi, we judged the CBX to be as good as it would get on adjustments alone. And it was very good. Nearly perfect, if kept below an 80-percent effort. Pushed harder, the CBX's weight takes over, it starts scuffing its way through wider arcs than you anticipate and its chassis no longer feels entirely solid. If your riding style entails diving into turns with closed-throttle, the CBX will shake its head a little, too, at the 80-percent level. The bike's steering remains neutral at a forced pace, and it is more competent at the game than all but a handful of other motorcycles. Even so, it loses some of its composure when hard pressed; both you and it will be happier with less forceful riding.

Maybe the best way for you to understand the CBX, to grasp what it truly is, would be to imagine that all of our highways had been made to curve around and follow the landscape rather than slashing through it. In that case America Honda's 1981 CBX would be incomparably the finest touring motorcycle. Others might be faster around a road race course or down a drag strip; others certainly will haul a bigger load of luggage. But if you were going to hurry long distances on roads not scribed as the shortest distances between points, the CBX would be hard to beat. So it isn't perfectly steady at the extremes of cornering, with the pavement striking sparks from its pipes; it's nearly effortless at 75 percent and can be ridden at that pace all day. So it doesn't have saddlebags much more commodious than big briefcases; it will carry a change of clothes. In short, the '81 Honda CBX will do what the best sports-touring vehicles have always done: It will take you to your destination quickly, and in glittering, riff-raff dazzling, six-cylinder style. Other considerations are beside the point. It can be shown by facts and figures that a 427 Corvette is better than an Aston-Martin, but ask yourself which one will make service station attendants call you "sir."