Test Categories
Overall Comfort
1. Suzuki GT550.............7.71
2. Suzuki GT380 ........ 7.14
3. Yamaha XS500C .... 5.71
4. Honda CB550F 4.71
5. Yamaha RD400C..... . 4.71
6. Honda CB500T 3.00
7. Kawasaki KH400 . 2.43
Overall Comfort incorporates aspects of several other categories—most notably Fit and Feet, Suspension Compliance and Vibration Control. This category very carefully examines a machine's touring suitability; 300 miles a day or more can become downright punishing without some measure of bodily comfort. Available alternatives, such as an air-conditioned car with bucket seats and a stereo tape system, mean a motorcycle has to be more than tolerable to have touring appeal to anyone not motivated by fanaticism. For the sporting rider, it's often a long way between the twisties, and he should not be expected to suffer just because his motorcycle gets its reputation from speed and handling.
Along with overlap from certain other categories, Overall Comfort ratings come mostly from the seat. This simple piece of leatherette-covered foam determines when your fanny muscles give out and leave you sitting on what feels like a hot rock. Indeed, the Kawasaki KH400 finished dead last in Overall Comfort primarily because its seat is contoured for a five-year-old's behind.
A complicated interplay of the bike's general performance determines its comfort level. All the aspects of suspension compliance, vibration, fit, noise, etc., combine with uncontrollables such as rough roads, winds, the weather and long distances to determine when fatigue sets in, The bikes which make you tired and sore the last rate first in this category.
The two Suzukis ran away with Overall Comfort because they have the best vibration control, a natural feel, decent suspension, quiet engines and wide seats. The same hefty weight which detracts from mountainroad handling adds stability and plushness to their feel. The 550 places higher because it can cruise with less shifting and its greater overall size provides more room for changing positions. Scores in the eights would have been easy for both GTs if the seats, which are well contoured, would have been softer and uninterrupted by passenger straps, which fall right about mid-cheek. Grips and levers—both too skinny—decrease comfort but don't actually promote fatigue, so do not effect scoring. Neither does the 550's kickstarter, which occasionally massages your right calf until you team not to crowd the engine so closely.
A score of 7.71 (which corresponds to "exceptional") pretty much sums up the 550's comfort. Of all the middleweights it comes closest to big bike comfort.
The Suzuki 380, which feels like a compact 550, finished a full 1 1/2 points above third place and just a half-point behind its big brother. It has all the 550's virtues except for a torquey engine. Therefore you shift a lot more and concentrate harder when going fast in the mountains or passing cars. Its 3-inch-shorter wheel-base crowds a tall rider more, but one of our six-footers still gave the 380 a perfect score of nine in overall comfort. Whatever it loses in size, it gains back in smoothness, and ends up being an enticing little mile-eater.
Yamaha's contra-rotating balancers can't quite settle the XS500C's buzz and thud completely, so vibration knocked down its comfort score more than any other item. Some people felt the seat would be better if it were slightly wider, and some complained that the handlebar bend caused lower back fatigue. It was also tiring to get jerked around by drive-train snatch in slow-and-go traffic. The XS is a long way from second place but it wasn't threatened by the bikes which tied for fourth.
Honda 550 owners may be outraged by the F's mid-pack tie with the RD400C, but to a man our seven testers all mentioned the same things: a hard, bench-like seat that had a passenger strap running across its one position; a stiff throttle with a too-long pull that got stiffer as the day progressed; a wide tank that put your knees out in the cold; and a snatchy driveline that is tiring to control. Of these criticisms the seat by far did the most damage to the Honda's rating. A 4.71 score is still a strong "average" rating.
In a tie with the Honda is Yamaha's hotshot RD400C, which cruises dead smooth at 65 mph, sits soft, barely hiccups at bumps and doesn't have much drive-train snatch. But high-speed riding brings out vibration, quick handling and a touchy rear brake that demands total concentration. And if you've got the wick up, be prepared to do a barrage of shifting and put up with a lot of intake drone and exhaust rap. The RD's seat is the spongiest of all, but not wide enough.
Vibration alone cancels the CB500T's chances in the comfort category, where it placed next to last. The handlebar could spin hula hoops at either end. With barely average suspension compliance, fit and noise control, the 500T would have to be parked to be comfortable.
The least comfortable of all is Kawasaki's KH400, partly because of a hard, skinny seat, vibration and the odd relationship between the pegs, seat and bars. Stiff suspension that's great for curvy-road handling but is nearly rigid on freeway seams ruined the KH's score.
Vibration Control
1. Suzuki GT380 . 7.86
2. Suzuki GT550 . 7.71
3. Honda CB550F.... .7.00
4. Yamaha XS500C 5.86
5. Yamaha RD400C . 5.14
6. Kawasaki KH400.... . 3.14
7. Honda CB500T 0.71
Vibration Control is very important in motorcycles, because most of them have engines that are natural vibrators. Single cylinder engines shake like mad vertically, horizontally, or a mixture of both depending on how much of their reciprocating mass is counterbalanced with weights on their crankshafts. Put two singles side-by-side to make a twin and there'll still be shaking even when the crankpins are spaced 180-degrees apart—as is almost invariably the case in today's motorcycles. No matter how the crank's balance weights are arranged there will be a rocking motion set off, and the rocking becomes a waggling when a third cylinder is added and the crankpins positioned 120-degrees apart. Adding a fourth cylinder, and a crank that pushes pistons one and four up while two and three are being pulled down, and you get rid of the rocking, but although in-line fours are in good primary balance there is a twice-crank-speed secondary shaking left to buzz your handlebars. Finally, even when the engine has two or more cylinders set in 90-degree "V" or opposed configuration (Ducati and BMW) there still is torque-reaction pulsing to be considered. Engines with six or more cylinders don't become rough until their piston displacements are much greater than anything suitable for motorcycfes, but there's only one six-cylinder bike—the Benelli—and it's not what you'd call a sporting middleweight by any means.
Among the middleweights participating in our test the two Suzukis vibrated least, and showed that vibration control can be effectively imposed secondarily even if nothing can be done at the source. Inline triples cannot be kept from shaking, and the Suzuki engines did their share. But the fours that power most small cars vibrate worse, and their vibrations would be enough to rattle the windows if transmitted straight into the cars' chassis. Rubber engine mountings do the trick for small cars, and have been used extremely successfully in the Suzuki GT380 and GT550, You do get some torque pulsing under full throttle, but at a steady statu-tory-limit-plus-15 mph cruising speed only a quivering gets from the GT550's engine to your body, and the smaller GT380 is dead smooth. We know the Suzuki triples were vibrating; that could be proved by stabbing a toe against the engine cases or exhaust pipes. But the vibration wasn't getting through to the frame, or shake-sensitive hardware like instruments and lightbulbs, or to the rider.
The Honda middleweight Four always has been smooth, and the present CB550F continues in that tradition. Our test 550 was as smooth as the Suzukis when cruising below 60 mph, and finished behind them in its Vibration Control score only because it begins to buzz at higher speeds and tingles your body pretty smartly when you're crowding the engine redline. So the way you'd rate the CB550F would depend very much on how hard you chase the revs. Cycle's test riders chased vigorously, and rated the Honda Four third in this category—almost a full click behind the winning Suzuki GT380.
A high-speed, high-frequency buzz cost the CB550 points, but not so much as to keep it from a high-exceptional rating. Yamaha's 500 twin didn't make it out of the "average" bracket, or out of fourth place. The XS500's flailing, chain-driven counterweights cancel about 90-percent of the vibrations generated by its two left-right, left-right pistons; the remaining 10-percepercent reaches the obtrusive level when you use the revs lavishly. And, of course, there's that twin-cylinder torque pulsing to shiver the 500's timbers, which does for the bike's low-revs running what dynamic imbalances do at big-number tachometer readings. The Yamaha XS500C is quite smooth under light throttle at a safe, sane (and abysmally dull) 55 mph; we treated it more roughly and it responded exactly in kind.
Yamaha pulled a page out of Suzuki's engineering-procedures book, and used rubber isolators to make the RD400 twin almost as smooth as its balance-shafted big brother. They stuffed tricky rubber sleeves between the engine/transmission case and its mounts, put rubber biscuits between the frame and the crossbar that carries the footpegs, inserted yet more rubber at the muffler attachment points, and rubber-bushed the handlebar mounts. It's a very extensive system of vibration-isolating devices, and it almost works. Here again, when the bike is ridden gently it's extremely smooth, but the RD400's engine won't make enough power to pull your eyelids open unless you get the crank spinning around 70-percent of redline revs, and right there's where you discover that rubber can only do just so much. What it does is a lot better than nothing, and provides respite from the old two-stroker tingle when you're joust cruising along, but falls well short of the Suzukis' vibration control.
Poke around the Kawasaki KH400 and you'll find about the same assortment of rubber-bushed attachments as on the Yamaha RD400, and more than are used in the Suzukis—which have the same inline triple engine configuration as the Kawasaki. The big difference is that the Suzuki vibe-isolation system works very well; the Kawasaki's, less than well. Even the Yamaha 400 twin, which is inherently rougher than a triple of the same displacement, was smoothed enough by its rubber mounts to score a full number ahead of the Kawasaki. We are inclined to think (and the KH400's fairly ferocious vibration level speaks for this hypothesis) that the Kawasaki was designed, but never fully developed. All the elements of shake-free riding are there, but only in the way that there is music in every guitar: both need careful tuning and shouldn't be expected to please until they've had it.
Honda's CB500T is long of tooth, long of stroke by today's standards and long overdue for either retirement or some kind of vibration control measures. You have to expect that a pair of side-by-side 250cc cylinders are going to set up a considerable shaking, especially at high crank speeds. And you should expect that the vibration created will be transmitted to the whole motorcycle if the engine is bolted solidly into the frame. That's what you'd expect, and the Honda CB500T isn't going to disappoint you. It shakes like the relic it has become, reminds everyone Who rides it that the good old days weren't all that good, and sends anyone with half a brain scuttling for the shelter of the nearest CB550F. The Honda twin finished last in this category, with a score low enough to put it tenth in a field of seven.
Overall Noise Control takes in more territory than the puffing of exhaust pulses through plumbing and mufflers, and the rider will hear things the EPA's sound meters might not even register—like the hollow jangling of fuel tanks against frame brackets at certain speeds. There's also that old two-stroke devil (which sometimes afflicts four-stroke engines as well) "intake honk," the rattle of drive chains and the gnashing of gears. Our personal evaluations of noise control are obviously biased toward overlooking mellow notes and acutely sensitive to sounds that grate on the nerves, which is another divergence from the results obtained in formal, instrumented noise testing. We won't bother to apologize for that divergence; we're more interested in telling you what seven human beings found appealing, and what was painful to their ears, than worrying about the opinions of soulless instruments.
Overall Noise Control
1. Honda CB550F.... .. ....8.43
2. Suzuki GT550 ...... .. ..5.77
3. Suzuki GT380 ..... ...5.74
4. Yamaha XS500C. . ....4.77
5. Yamaha RD400C.... . 4.43
6. Honda CB500T .........4.43
7. Kawasaki KH400 . .4.14
Honda's flying trench horn, the CB550F, won the Overall Noise Control contest hands down, with a score almost as high as the combined total of the sixth and seventh-place losers. The Honda Four doesn't make much noise at all, and what you do hear is nice. There's a high-pitched, subdued singing from the single muffler, and counterpoint notes played by intake resonance. We're sure there must be a percussion section, if only in the slamming of chain rollers against sprocket teeth in the Honda's final drive, but any jarring sounds are lost in the wind whipping around a rider's helmet. The Honda gives you sound; it spares you noise.
The good folks at Suzuki probably will be surprised to find that their GT550 and GT380 triples didn't finish the noise category in a tie. After all, the two bikes are very similar in design, are creatures of the same technology, and were created by the same design team. The difference is that one is bigger than the other, and the little GT380 had to keep up with the bigger Suzuki, which meant more throttle, more revs and more noise. You don't hear much mechanical noise from either of the Suzukis, but they do work up an exhaust bark when pressed hard and back it with a deep, hollow honk from their triple carburetors. The amplitude of these sounds is very much a function of throttle setting; the GT380 made most of the distance we traveled with its throttle cables stretched tighter than banjo strings; and that's how it came to be scored below the GT550.
We found another close throttle/amplitude relationship in the Yamaha XS500C, and an exhaust beat with a curious waffling quality one of our testers likened to "A herd of small, flatulent bison." With enough throttle applied, the Yamaha's riders couldn't hear more than a hint of its exhaust noise, as the intake drone then overwhelmed everything. Everything, that is, except for some fuel tank rumbling and the rattling coming from inside the engine—which seemed to be the chain driving the Yamaha's balancer. Ridden at moderate speeds and on light throttle the XS500C makes about the same noise, in quality and intensity, as a sewing machine. Push it, and you get a moderate-but still very noticeable—hoot, waffle and clatter.
You won't find any balancers in the Yamaha RD400C; only rubber vibration isolators keep the rider from feeling the engine shake, and this approach has worked to the extent that Yamaha's new two-stroke twin is smoother than last year's RD350. Alas, although the engine shaking can't be felt, its effects can be heard. The RD400's mufflers are effective, to a point, and the intake sounds are damped by a baffled air cleaner box—also to a point. But when the Yamaha is head-down, throttle-slides up and charging, you do hear air going in, exhaust gases passing out, and the drumming jangle of hardware which (unlike the rider) is not protected from engine vibration.
Honda's CB500T is now more than a decade old, and vibrates worse than most 1966 motorcycles, and the vibrations set off the kind of racket those who were around the sport during the Sixties will remember well, if not fondly. Muffling is now being done more effectively than in days of yore, and the system on the Honda twin left it with a flat splatter that pleases sound meters but offends people—and unmasks a cacophony of whirs, clicks, and tinny ringing. The Honda twin isn't loud, but then neither is a strangled whimper. We liked the bike better when it still had its roar.
The Kawasaki KH400 triple was loud in every way a motorcycle can be and still squeak past the government's maximum sound level test. Two-stroke engines tend to have a sharp, rattling exhaust note, and a deep-throated intake growl. The Kawasaki had those. All things mechanical produce gear-whine, bearing rumble, and a cowbell thonking when there are thin-walled castings surrounding the moving parts. And the KH400 had those noises in abundance, including a rhythmic yowling that said a "hunting-tooth" primary drive gearset had at least two teeth that weren't friends, and helped make this fast, good-handling triple less friendly than it otherwise might have been.
Suspension Compliance
1. Yamaha XS500C.... ...6.43
2. Yamaha RD400C.... ..6.00
3. Suzuki GT550 ....... ....5.71
4. Suzuki GT380 ...... ... 5.77
5. Honda CB550F ..... ....4.77
6. Honda CB500T ..... ....4.74
7. Kawasaki KH400 . 3.29
Suspension Compliance has for many years been a quality markedly lacking in sports-touring motorcycles, and only recently has the situation begun to improve. Motocross bikes' great leap forward has been in the areas of suspension travel and damping, and it would be nice if the lessons learned there had direct application in the development of road machines. Unfortunately, while better suspension dampers can be applied to your favorite street tooter without undesirable side-effects, sheer suspension travel is not without its darker aspects—producing the kind of fore/aft pitching that makes pavement pounders behave very peculiarly. The real improvement in road-bike suspensions has been in the area of multi-rate springs, an overall softening of spring rates permitted with better damping, and measures taken in the interest of reducing to more tolerable levels the static friction between fork tubes and their sliders.
Yamaha stole a march on the rest of the Japanese motorcycle industry by grasping the full import of, and doing something about, the telescopic fork's "stiction" problems. Fork sliders would move easily on their tubes if presented perpendicularly to the road surface, but the requirements for stable steering have produced the familiar inclined fork mounting, which places a cantilevered toad on the sliders and tends to make them bind. Forks' static friction is rarely great enough to compromise their ability to move for large bumps (which, if sufficiently large, either cancel or even reverse the cantilevered load). It's little ridges, like highway expansion seams, that are still responsible for the typical road bike's ride-harshness problems, and most of the jolting comes right up through the fork. BMW handled fork stiction by using very long sliders, making room for them with forward-mounted axles, with sheer length and precise manufacturing techniques reducing the binding. Yamaha has taken a different approach, with forks that have a low-friction plastic liner in the top of each slider—and this solution works extremely well. Yamaha also seems at the same time to have invested development time and money in the more subtle aspects of suspension technology, including the sorting-out of spring rates and damping with closer attention to results and less fixation on manufacturing costs.
Differences between the Suspension Compliance King, Yamaha's XS500C, and the RD400C that finished slightly more than a half-point behind, were in degree rather than in kind and were about what you'd expect from the differences in weight. Both Yamahas had very supple, well-controlled suspensions and, though riding on quite soft springs, did almost none of the leaping and pitching once associated with low spring rates. We had their tires inflated at the maximum recommended pressures (this was done with all the test bikes) and their cast-aluminum wheels seem to make the Yamahas' ride a bit harsher under some conditions, so the XS500's and RD400's rides were not in the Cadillac class. These bikes, did, however, offer a ride quality markedly better than the others and really earned their first-second finishing order.
Our two Suzukis tied for third and fourth places in the Suspension Compliance category, and did it on entirely conventional but obviously well thought-out suspensions. They have the same problems with high unsprung masses and low polar moments of inertia that presently (and perhaps forever) make all motorcycles ride a trifle jouncy. But you would be hard pressed to fault Suzuki for effort: the firm's engineers have made the most of a suspension layout everyone uses; the others just don't use it as well. The Suzukis didn't make it across expansion seams with quite the unruffled equanimity of the fric-tionless-fork Yamahas, but they were awfully good.
Honda has a well-deserved reputation for making exceedingly refined and reliable engines, and the Japanese giant has demonstrated with the CB550F that it knows what to do about balance and steering geometry. But even though the 550 is one of Honda's best efforts in terms of ride quality, the Four simply is no match in suspension compliance for the Yamahas and Suzukis. You ride those bikes for a couple of hundred miles, then climb aboard the Honda, and suddenly you're back in 1966. The CB550F is too stiffly suspended, its damping doesn't feel especially well-suited to anything except a cost-accountant's edict, and the bike simply jiggles around a lot.
Honda's CB500T will take you back to the worst of 1966. Its suspension is all springs and no damping, and the most that can be said of the way it rides is that it's a match for its own engine harshness. The 500T fork and rear suspension struts will move, albeit reluctantly, for major potholes and bumps bigger than a breadbox; it treats lesser road-surface discontinuities with a disdain worthy of nobility— but badly out of place in a motorcycle.
And in last place we find the Kawasaki KH400, which hands you the kind of ride quality that should be reserved for convicted axe murderers on their way to the execution dock. The bike's dampers don't work much, but then its springs are stiff enough so the suspension doesn't move but about twice a day anyway. Kawasaki's 400cc triple handles well and it goes like a little rocket, but the bike is such a stiff-legged brute, so clattery on even the smoothest surfaces, that it may as well not have a suspension system at all. You may like the way this bike goes, as we did; you won't like the way it feels. That's the way we saw it, and scored the Kawasaki solidly and uncomfortably into Suspension Compliance's very last place.
Fit & Feel
1. Honda CB550F.......... .6.29
2. Suzuki GT550 ....... . ...6.14
3. Suzuki GT380 ...... ...5.86
4. Yamaha XS500C..... ..5.77
5. Yamaha RD400C... ....5.29
6. Honda CB500T ..... ....4.29
7. Kawasaki KH400... ..3.00
Fit and Feel scores reflect very subjective judgments of how well motorcycles function as control platforms. Some bikes lend themselves to the formation of a man/machine centaur, in which the rider is able to use brakes, engine, transmission and steering in almost the same way he uses his limbs. Others tend to keep a rider thinking, and trying to cope with handlebar grips, levers and footpegs that simply aren't where they should be—causing cramped muscles and cricked necks on the straight-and-level and requiring the sort of awkward compensations that put a ragged fringe on the most polished of riding styles. We don't know how Fit and Feel could be weighed, smelled or tasted, we don't know that it could even be dimensioned, but after years of riding all kinds of motorcycles and after days on the road with this sampling of machines, we sure know what it is, and isn't.
It's worth noting that even the category-winning Honda CB550F scored nowhere near an "outstanding" (nine). Most of its points were earned through having very smooth-working controls, and seat/handlebar/footpeg relationships that were at least fairly close to being right. Points were lost because the 550's shift lever, while falling readily to foot, was notchy and uncertain, and because the wonderfully precise throttle takes 120-degrees of rotation to pull the slides wide open, which is roughly twice the twisting movement a human wrist can comfortably provide.
The two Suzukis, GT550 and GT380, finished just behind the Honda Four, and might have come in ahead of it in this category but for an unfortunate (for them) set of conditions. In fact, the Suzukis have just about the nicest placement of seats, pegs and handlebars we've found, and the handlebars themselves are marvels. Both Suzukis have their footpegs a bit far forward for anything but just teetering around town, and that's true of most touring bikes. Where the Suzukis really went wrong was in having too-narrow handlebar levers, which began to cut into one's fingers after the twentieth hard squeeze, front brakes that required a lot of squeezing before they'd work effectively, and seven test riders who were unable to resist the temptation to crowd their luck on any road with curves in it. So luck was crowded, narrow brake levers were squeezed mightily, and the fingers that suffered the consequences held the pencils when score sheets were marked. On a less frenzied, non-white-knuckle tour the Suzukis would fit, and feel, better than anything in the class.
Yamaha's XS500C situates its rider squarely between a rock and a hard place. If he slides back on the seat until the handlebar begins to feel comfortable, the footpegs become a long, awkward way forward; sliding forward to get the pegs under his body's balance point gets the hand/handlebar relationship out of kilter; the midway position treats him to both discomforts, and neither is much diminished. Most of us alternated between the extremes, sitting forward until our wrists began to go and then sliding back until leg-cramps set in. The XS500 was so close to being right we rated it better than average, and far enough from an unqualified right to fall into fourth place.
Everything said about the Yamaha 500's mismatched handlebar and footpeg locations is true of its smaller, two-stroke brother, the RD400, which has the same problem but in slightly more severe form. Also, for no logical reason, the smaller bike's clutch action is much heavier, and its throttle return springs more determined to overwhelm its rider's efforts to hold the throttle slides open. Beyond those things, none of the controls work as smoothly as they should, and the man who buys a Yamaha RD400C could increase the bike's controllability and his own riding pleasure by doing a bit of custom fitting and adjusting. The Yamaha 400 is as sudden as a thunderclap; you wouldn't want any misunderstandings about what you've asked it to do.
And then there's the Honda CB500T, which fits about right but feels horrible.
Apart from having pegs and handlebar positioned for the mouth-breathers who never venture beyond the city limits, the Honda twin isn't a bad fit. But even though you can work the controls without undue effort, the control response is just wretched. Throttle response in particular is enough to provide a rider many trying moments, because there's no modulation between closed and what feels like quarter-open. You might as well try to turn on the Honda's headlight slowly as to find a power setting between idle and 25-percent. And the gear change mechanism feels like it must be full of sand, or malign spirits, and the way the right footpeg stands out farther than its mate on the left doesn't help matters a bit.
Kawasaki's KH400 can be made to whip around very smartly, but not without some extraordinary exertions on the part of its rider. Name your control-platform poison, and the Kawasaki triple will serve up a magnum-size swallow: its handlebar is wrong, its pegs are far too far forward, the shift lever has to be forced into movement, the clutch engagement point is no broader than a point, the distance between pegs and the narrowness of its fuel tank have you sitting knock-kneed, and there's a thicket of sharp-edged hardware jabbing at the insides of your ankles.
In-Town Ease of Operation
1. Suzuki GT550....... ..6.29
2. Yamaha RD400C.... .5.57
3. Honda CB550F ........ .5.29
4. Kawasaki KH400 5.29
5. Suzuki GT380 .........5.74
6. Yamaha XS500C .... .4.71
7. Honda CB500T 2.71
In-Town Ease of Operation is based on braking, clutching, gear-changing, carburetion, performance and general layout of the controls. Steering response, balance, vibration, acceleration, noise and ground clearance limits also come into play.
The ease with which the Suzuki GT550 can be ridden through traffic is mainly attributable to its exceptionally torquey engine. It departs from a dead stop smoothly, moving quickly within a power spread that begins at 2500 rpm. The clutch engagement point is broad and progressive and free of snatch. The engine's broad torque band makes for a minimal amount of gear-changing. The first three—sometimes four—gears handle most in-town situations.
The 550 Suzuki's slight amount of compression braking reduces throttle shut-off snatch to a minimum. Exceptional comfort and smooth performance above 2500 revs minimize irritation and fatigue inflicted on a rider during multi-mile commutes. The Suzuki 550 feels large and somewhat clumsy at walking speeds. Sharp left hand turns, if taken too briskly, will catch the side/center stand tangs.
The next four bikes, while scoring below the 550 Suzuki, were grouped closely together in the points tally. Yamaha's 400cc two-stroke twin is the most exhilarating and nimble of the bikes (or running stoplight-to-stoplight. The relatively close-ratio six-speed gearbox provides a tall first cog, but the abundant power of the Yamaha engine gives rocket-like acceleration from a stop.
Of all the bikes, the Yamaha 400 has the quickest steering and, delightfully, knifes through thick traffic with minimal rider effort. Prudence must be used with the throttle hand because of the Yamaha's near-explosive power surge, which can bring the rider past the speed limit entirely too quickly. The saddle is comfortable around town and the supple suspension soaks up potholes and surface ridges. Good tires and superb brakes are accompanied by generous ground clearance. Kick-lever starting is a hindrance if the engine is stalled at a stop light, and the grabby clutch and sudden power peak require full attention on sandy or damp pavement.
Honda's 550 Four has a tremendous power spread, which allows for two-gear in-town cruising. Its exceptionally quiet exhaust and intake baffling keep it from annoying other commuters. The engine's decelerating force on closed throttle is convenient when running up and back within a ten-mph speed range.
The CB550F has an irritating amount of throttle-to-rear-wheel lash and wind-up. The engine has to be run high in its rpm band to develop maximum power. Honda's quick-connect clutch doesn't promote smooth gear changes or leap-free departures from a stop when the rider is in a hurry or when the revs are high in the engine's speed range.
Kawasaki's 400cc two-stroke triple tied with the CB550F in this category, but the bikes' performances were vastly different. The Kawasaki, like the Yamaha 400, is light, quick and fast. The KH400 produces more mid-range torque than the Yamaha two-stroke while having a near-identical power surge.
The Kawasaki weighed in as the lightest in the field, which is beneficial when flicking through congested streets. Steering is precise and the taut suspension and generous ground clearance make for surefooted cornering. Marring the KH 400's performance in town are its bone-hard seat and rigid ride; they jar the rider and make him feel every ripple on rough surfaces. Electric-shock vibration, a weak rear brake, odd-shaped handlebars and manual starting detract from the 400's in-town suitability for most riders.
The Suzuki 380 triple offers great comfort for short-haul riding. The rubber-mounted engine certainly does not deliver any of its vibrations to the chassis or rider. The six-speed gearbox allows for the exact setting of engine speed to meet most situations. Power delivery is smooth and without the rush produced by the Kawasaki and Yamaha 400s. Steering is neutral and the suspension softly sprung.
The Suzuki is heavy for its displacement and acceleration suffers. Gear staging in the lower two cogs is not especially well-matched to the engine's power and minimal ground clearance prevents cornering speeds from reaching a frisky level.
Yamaha's revamped 500cc four-stroke twin is smooth, quiet and superbly suspended for comfort. Front and rear discs offer excellent stopping power, although a gentle touch is required with the grabby back brake. Like the Honda 550, the Yamaha has a lot of slack in the throttle-to-rear-wheel connection; that requires the rider to use lower engine speeds on slippery surfaces. The high-revving twin demands wide-open throttle for brisk acceleration and the valve train clatter is an annoyance to the round-town rider.
The CB500T has an adequate amount of power, is geared correctly and steers with only a slight heaviness. Comfort on the street is acceptable and the saddle is low enough for most riders to touch both feet to the ground. Quick acceleration requires high engine speeds, which generates fierce vibration, vicious shaking of the bike's extremities and total blurs in the rear view mirrors.
Engine Performance
1. Suzuki GT550.............8.00
2. Yamaha RD400C.... ...6.77
3. Honda CB550F ....... ..6.43
4. Kawasaki KH400..... ..6.14
5. Yamaha XS500C..... ..5.29
6. Suzuki GT380 .... .......3.77
7. Honda CB500T... ..2.43
Engine Performance, as pragmatically defined by our testers, involves a host of difficult-to-separate characteristics. Peak horsepower, of course, is one primary consideration. So is top speed, useful torque range, willingness, and what we call "accommodation," or that peculiar ability to perform tasks the operator calls for when he calls for them. The category winner, with the second-highest average score of the entire comparison, is the GT550. The bigger of the two Suzuki two-stroke triples makes just under 32 bhp on the dyno at 7000 rpm; more importantly, it produces 21.5 Ibs/ft of torque at 2500 rpm and doesn't fall below that figure until it reaches 7500 rpm, which means that the GT550 will respond aggressively to increases in throttle opening at practically any engine speed and in practically any gear. The engine is responsive, gentle and easy to get along with, and it doesn't need an expert's touch. It does well with brisk engine speed, but it doesn't absolutely demand it, and the 550 can trickle peacefully through the center of town without a lot of clutch-slippage and shift-kicking. Beyond the outskirts, watch it—the 550 Suzuki proved, over a series of head-to-head flat-out charges, to be the fastest bike in the comparison, just edging out the CB550F Honda. Its fuel economy is nothing to rave about—33.9 mpg average—but it's not the worst either, that dubious distinction having been claimed by its little brother. It does a nice job of isolating its rider from vibration and noise, leaving the operator with nothing but pleasant sensations from below.
Ranking second in the Engine Performance category is the Yamaha RD400C two-cylinder two-stroke. The long-stroke motor, new for 1976, is a perfect example of compromise without sacrifice. It's a tad torquier than its 350 predecessor and notably less abrupt—but it can jump up on top of its power curve and streak if that's what you want. It's an easy starter, rough on spark plugs (our first set was scabbed-up after less than 400 miles), smooth, somewhat noisy, and willing to a fault. The RD was the most demanding bike of the seven—but its engine rewarded an enthusiastic wrist with absolutely thrilling acceleration and response, and contrary to what you might think, the 400 has enough torque to make traveling with restraint an attractive option. (It could outpull the GT-380 Suzuki even if the Yam was in sixth and the 380 was in fifth.) But we were a bit surprised that this particular RD400C wasn't even faster. It had entered the comparison at the last minute after our original (and fresh) RD had suffered a transmission problem, and although its engine performed notably, the replacement 400 wasn't as good as we know typical RD powerplanls to be.
The Honda CB550F's four-stroke multi-motor finished third in this category, again penalized by a laziness more apparent than real. To make the Four really sing, the rider has to grab it by the scruff of the twistgrip and wear out his right hand to overcome the heavy return spring and the long-travel throttle. With a more responsive linkage the Four would have done considerably better; it's smooth, energetic and potent, qualities which rapidly over- power its cold-bloodedness on chilly mornings and its drive-line snatch.
Behind the Four came the Kawasaki KH400: an engine which acts much like the RD's but less so. The motor honks through its inlet system, shivers with vibration in the higher rpm ranges but is responsive, perky and hard-working. Its average fuel consumption rate was 32.5— which doesn't sound like a lot, but reflects an improvement that has been evident for the last three years. When introduced in 350cc form, the smallest imported Kawasaki triple would inhale gasoline at 23 mpg. The newest version is much better— the KH400 makes just over 100 miles before reserve is switched on. The engine is very much in the Kawasaki two-stroke triple tradition, and it's a tradition that our test crew (a sporting lot if ever there was one) found attractive.
The Yamaha XS500C finished fifth, its engine performance rating downgraded by its snatchiness, its valve-train/balancer unit clatter, the reduction in its power output brought on by heat build-up, and certain intrusive mechanical resonances. But the test staff was ambivalent about the SOOC's power band. Some approved of what felt like a nice, flat torque curve; others felt that the engine had to be revved exceptionally hard to produce good performance, and the higher the engine speed and the more abrupt the gear changes, the worse grew the carburetor/transmission lurch.
Next-to-last in the engine performance evaluation was the Suzuki GT380. Its power output is just under 31 on the dyno, and its peak torque is 20.8 at 7500. Those figures, combined with its all-up weight of 413lbs., hurt when compared to the bikes whose engines were rated above it. The engine is small; the bike is heavy. It ought to be slow, and it is: 15.14 seconds in the quarter-mile. Slow ain't all: the 380 consumed fuel at the highest rate (31.7 mpg), and during our test the bike had an oiling problem that turned the surrounding atmosphere blue.
Finishing last, with a 2.43 average score, is the Honda CB500T. The engine was beautifully credentialed ten years ago—but the passage of time has really punished it. When the 500T was a 450 and the year was 1971, the bike got a rave review in Cycle. But in 1971 none of the other bikes in this comparison existed. If the 500T can be seen as a living history lesson, well and good; but it's not so hot for anything else. Its engine vibrates and snatches and has a power peak so high (33.98 at 8500) that few of our testers were willing to explore it, the engine's shake-level being what it is. Not that the bike is an excruciatingly slow one—its 14.83 @ 85.55 figures in the quarter-mile are respectable enough—but it's just so doggone unpleasant.
Mountain Road Suitability
1. Yamaha RD400C...... .7.58
2. Kawasaki KH400....... 7.00
3. Yamaha XS500C...... .6.57
4. Honda CB550F ....... ..5.77
5. Suzuki GT380 ...........5.43
6. Suzuki GT550 ...........4.86
7. Honda CB500T . 0.86
Mountain Road Handling takes more of a motorcycle's characteristics and capabilities into account than any other category. To score well here a bike has to have more than satisfactory cornering clearance, a tight connection between throttle opening and ground speed, intelligent gear ratio spacing, predictable and decisive braking action, a solid chassis, and suspension components that function well and stay consistent. We weren't particularly surprised that the RD400C was a clear-cut winner here, even though, according to three testers, "It's an expert's bike." The hot-eyed little Yamaha has everything going for it blasting through the twisties: it's suspension is supple without being mushy, it's ground clearance is ample, its brakes if anything are too powerful, its engine is quick and eager (although it likes to be kept above 6500 rpm), and the ratios in its six-speed gearbox appeared to be perfectly calibrated to the motor's fish-hook power-band.
But the bike does have to be gotten used to. Its low center of gravity and its 52 1/2-in.wheelbase make the RD400 lightning-quick; every directional input is responded to instantly, so what you think you want to do better be what you really want to do.
Supple the RD400C's suspension may be; but the rigidity of its cast wheels transmitted a certain harshness going over severe road-jolts that more resilient wire wheels may have absorbed. (The same characteristic was noted of the XS500 Yam, which also has one-piece alloy wheels.)
As demanding of one's concentration as the 400C is, and as difficult as it is to familiarize oneself with, the test crew learned quickly how to hustle it along through the mountains. Finishing second to the RD was a bike that nearly matched its character: the Kawasaki KH400. It may not be good for much else, as one of the test-crew pointed out, but it is fun to ride con brio. Its suspension feels stiff and springy buzzing down the Interstate, but the bike goes where you want it to go and does what you want it to do in slash 'n' terrorize winding-road riding. Our testers felt that the KH400 was penalized by its peculiar handlebar bend, its vibration level and by its heat-prone rear brake. Too, our KH went into detonation climbing up a twisting sea-level road, which didn't seem to hurt our bike but may demoralize yours. It also had a tendency, like the Yam RD400, to jerk its front wheel off the ground accelerating away from low-gear turns. Its transmission and clutch functioned flawlessly, and its enthusiastic engine response and decent power-spread made the Kawasaki easier to ride than the Yamaha RD.
Finishing third in the twisties was the slightly surprising Yamaha 500 four-stroke twin. Sound of chassis, the XS500 tracks accurately and has plenty of power, although it likes to turn up a fair amount of engine speed before that power becomes authoritative. Its brakes were rated second only to the RD's. It retains its composure nicely down ultra-fast winding roads, but feels a bit rubbery through bump-infested corners.
Its biggest problem in the mountains was the unpredictable connection between the twist-grip and the rear wheel. The XS's transmission slop, common to most Japanese street bikes, was aggravated by its Mikuni vacuum-slide carburetors. The "constant-vacuum" concept may work well in some applications; it has never worked well on motorcycles, and is particularly noisome on the Yamaha 500. The bike lurches when you roll the throttle off, it lurches when you roll the throttle on, it is oversensitive to small twist-grip adjustments (it sometimes even reacts to bumps in the road), and at high engine speeds the engine does not respond to the quick throttle-blip necessary for smooth downshifts. Still, the XS500, snatchy drive-line and all, was appealing for most testers, primarily because of its chassis integrity, exceptional cornering clearance, good suspension control, nicely balanced brakes and sufficient power.
In the dead center of the Mountain Road Handling order is the Honda CB-550F, a bike with clearly ample power and good brakes but also with a host of small and subtle problems that plot against it. First, the CB550F's plusses: its four-cylinder four-stroke engine spins out power smoothly and in a direct relationship to engine speed. The red line is set at 9300 rpm; anything above 6500 rpm will yank you forward encouragingly. The Four is the most tightly-integrated bike in the comparison; the controls respond with a unanimity lacking on the others. The bike's feel is taut, bright in a silky way, not harsh but solid. One's initial impression of the 550F is that the bike has a sting muffled but not obscured by its sophistication and that you could live with it— happily—for a long time.
But the subject here is mountain roads, and the 550F left our test crew with a vague feeling that it was not all it promised to be. For starters, it's afflicted by the same snatchiness common to all high-performance Japanese multis, caused by its lack of flywheel inertia and the gaps between the engaging dogs in its transmission. The last thing in the world the Four is is unwilling—but its throttle linkage makes it feel that way. The resistance to twistgrip rotation is pronounced here, brought on by heavy return springing and by far too much twistgrip travel. The travel is necessitated by the return springing; a quick throttle would take an ungodly amount of wrist torque to manipulate. If Honda could shed its paranoia about sticking carburetor slides then they could lighten up on the return spring; if they lightened up on the return spring then they could use a quick throttle; and if they could use a quick throttle the engine would feel as perky and responsive as it really is. But as things stand now the Honda 550 feels like it has to be pushed hard to deliver brisk mountain road engine performance, and in a comparison that includes such light-switch leapers as the Yamaha RD400C and the Kawasaki KH400, the CB550 is going to suffer.
It also suffers in its attempts to negotiate bumpy sweepers. Its primary stability is just fine; once it's pushed just past its limits, it's less than fine. Blast it through some fast, rough stuff, especially after the suspension fluids have had a chance to get nice and hot, and a mild attack of the old pitch-and-wobbles sets in. To have an insufficiency of ground clearance on both sides is plenty bad; to have a problem on one side only is worse, especially if you happen to forget which side is the bad side. The Honda's trendy four-into-one allows unlimited cornering clearance on the left; on the right, nightmare-city. The 550 drags its header pipe, its collector system and its brake pedal, and when it's shooting sparks with all three you're only microns away from real trouble. The old 550 four-piper didn't have the F's cornering clearance problem; it's always a disappointment when trendiness intrudes upon function.
The two Suzuki triples finished fifth and sixth in the High Mountain GP, the 380 higher-ranked than the 550 because its hard-working little engine and its slight weight advantage respectively reduced its speed potential and gave it more side-clearance. Although the 380 never fell behind because of its power-down problem, it had to be thrashed to stay in the hunt—and thrashing's a dangerous deal on a bike that drags its belly on the ground whenever it faces a turn. The 380's brake
action was fine, and it is a responsive, willing little worker. But those things that helped its comfort rating—like soft suspension—hurt in the turns. The softer the springing the more a bike will squat under cornering loads; and the more it squats the less clearance it has. The 380 doesn't have much to begin with, and once you've used up the bike's allotment you're about to use up your own. In most regards the GT380 is a brilliant little piece. It's a mess in the mountains, and until Suzuki gets it in its mind that decent cornering clearance is obligatory rather than optional, a mess in the mountains is what the 380 will continue to be.
The same holds true for the 550, only more so.The GT550 earned its miserable mountain road score fair and square, and it was thought of as worse than the 380 primarily because it's faster, and consequently more dangerous. Too, the test staff resented this one great flaw in an otherwise superb presentation, causing its mountain behavior to stand out all the more glaringly. The 550 has a three-into-one-into-four exhaust system that may well be a chrome-plater's dream, but the system consumes so much under-chassis space that if the muffler section doesn't drag, then the various stands will—and do. Power delivery, braking force and control layout on both Suzuki triples are all above reproach—but a lack of cornering clearance ruins both bikes for energetic curve-charging.
Ranking last, with one of its two below-1.0 category averages, is the Honda CB-500T. It earned it with a conspiracy of shortcomings that can only be defined as magnificent. The 500 has everything and does everything necessary to guarantee that your teeth will be clenched and your knuckles white at the end of an even moderate lunge at a winding road. It has no system to mute the wicked vibrations coming from the vertical parallel twin engine; its brakes both feel mushy compared to the brake systems on the six other bikes; it is afflicted with a near-terminal case of drive-line snatch that's severe enough to make smooth riding a practical impossibility in any situation calling for throttle modulation; clutch engagement is grabby; the footpegs are too far forward, and stick out too far; the rear brake lever drags brutally going around right-hand corners, and the linkage is designed so that every movement of the swing arm causes movement of the brake lever; the bike's stability goes to hell whenever it's faced with a turn with a bump in it, or a bump with a turn on it. The seat is satisfactory, and the transmission is likewise. But not satisfactory enough to make up for the rest of it. Some candid test-staff comments: "Honda continues to build the CB500T to let you know how far they've come." 'This bike is too old." "I'll forget it if Honda will."