At the time, it seemed like the greatest idea since the invention of the wheelie: a dual-purpose bike with performance. "It" was the KL600R, Kawasaki's long-awaited entry in the Open-class dual-purpose sweepstakes. And when the KL was introduced late last year, it looked to have it all: a 600cc, single-cylinder, four-stroke engine that not only had four valves but dual overhead cams; that was not air-cooled but liquid-cooled; that used not just one engine counterbalancer but two.

Not only that, the engine's top end had the same profile as the new 900 Ninja's, and the whole business was carried in a single-shocked, disc-braked chassis that featured a box-section aluminum rear subframe. And when all of this was combined with the fact that the KL600R was being built by Kawasaki, the Oriental hot-rod company that had brought us such legendary pavement-wrinklers as the Mach III Triple, the Z-l, the GPz series and the fearsome 750 Turbo, there was only one conclusion to reach: The KL600R is one serious machine that is going to be the most fire-breathing dual-purpose motorcycle ever built. Period.

Apparently, something got lost in the translation. The KL600R's performance is, shall we say, a bit off the bull's-eye. And you only need look as far as our recent road tests of Honda's XL600R and Yamaha's XT600 to see just how far it is off. Our KL's best run at the dragstrip was 14.28 seconds with a trap speed of 88.88 mph. That's about half a second and 6 mph slower than both the Honda and the Yamaha. The Kawasaki's 97-mph top speed is 3 mph below that of the XT and 6 mph less than the Honda's. A look at top-gear roll-ons is equally distressing. The KL takes 5 seconds to accelerate from 40 to 60 mph; Honda 4.3, the Yamaha 4.6. From 60 to 80 mph the the Kawasaki requires a full 7 seconds, while both the Honda and Yamaha need only 5.6, which is almost a second and a half less. In fact, even Honda's XL350 is quicker in that respect.

From these figures, an educated guesser would say that the "technologically advanced" Kawasaki is about 5 horsepower down on its more-conventional competitors.

Just why the Kawasaki is lacking in power is a mystery, even to the company's U.S. officials, who just shrug their shoulders when asked where the horsepower went. At an actual 564cc, the KL gives away displacement to the 595cc Yamaha and the 589cc Honda, but the engine seems like it has enough techno-features to make up for the handicap.

Liquid-cooling, for example, has been associated with high-performance motorcycles because it provides more-uniform engine cooling, which allows closer tolerances and, theoretically, a higher state of tune. But the KL, if anything, seems to have a lower state of tune.

In design, the Kawasaki's cooling system is just like those used in recent moto-cross engines. There are two small radiators mounted in front of and just below the gas tank, and the coolant, a recommended 57/43-percent mix of water and anti-freeze, flows from the rightside-mounted water pump to the cylinder head. From there, coolant is pumped through a thermostat to the right radiator, behind which is mounted a small, eight-bladed fan to help out when things get really hot. The coolant then crosses the frame to the second-stage radiator and is routed via a rubber hose back to the pump. Black, cowcatcher-style air shrouds made of plastic direct air through the radiators.

In practice, the bike's cooling system worked nicely. The instrument-panel temperature-gauge needle usually hovered at the halfway mark, and the fan cut in only a few times during the KL's 2000-mile, late-spring test. One drawback to the system is that the rider's legs are warmed by hot air flowing through the radiators. Not bad on a cool spring night, but stop-and-go traffic on a humid summer day is another story. We also expected the liquid-cooling to be more effective as an engine-noise buffer, but the KL made enough banging and rattling racket that several bystanders gave a quizzical, is-that-thing-all-right look at the idling Kawasaki.

Water-cooling isn't the only area where the KL's engine differs from its competition. Both the Honda and the Yamaha have four-valve cylinder heads that's almost expected of four-strokes these days but their valves are operated by a single camshaft. The Kawasaki has two cams, chain-driven from the crankshaft. The use of double overhead camshafts is usually reserved for high-revving engines, where the lighter valve gear yields less reciprocating mass compared with a single-cam design. And while it's true that redline on the Kawasaki is set 1000 rpm higher than it is on the other dual-purpose big-bores, the twin cams haven't helped the KL close the horsepower gap.

Another difference in this atypical engine is the oiling system. Most large-displacement dual-purpose and off-road four-stroke Singles use dry-sump systems. Although this type of oiling requires the use of a separate oil reservoir—the Yamaha uses a side-mounted oil tank, the Honda a frame-tube reservoir it allows a lower engine height, which is an important consideration for inherently top-heavy four-strokes. But the KL600 utilizes a wet-sump oiling system, mainly because the company's recent streetbikes and its dual-purpose 250 all use wet sumps, and that's the type of oiling system Kawasaki's engineers are most familiar with. Plus, the feature-packed KL600 already is $50 more expensive than the Yamaha and $103 higher than the Honda, and a dry-sump system would have added to the KL's price.

Indeed, but the wet-sump system has added to the KL engine's height, for the need to carry the oil under the crankshaft has made the engine taller about one and a half inches taller than the Yamaha's engine, for example. Surprisingly, the KL doesn't feel any more top-heavy than the Honda or Yamaha. This despite the extra height of the engine, the high location of the radiators and a test weight, at 325 pounds, that is seven pounds heavier than the Yamaha's and 10 pounds up on the Honda's. The KL's engine does, however, have a distinct advantage over the XL's and XT's in that Kawasaki fitted the 600 with counterbalances to smooth out the big Single's vibration. Both the Honda and the Yamaha use single, gear-driven counter-balancers, and while these systems help quell the shaking, there's enough left to spoil long highway trips. The Kawasaki, on the other hand, is smoother at cruising speeds, smoother, even, than some road-only bikes. At an indicated 60 mph (actually 54 mph, the speedometer is hopelessly generous) the footpegs are almost buzz-free and the handlebar passes only a slight tingle to the rider. As the revs climb past 5000 rpm, a typical big-Single vibration returns, but the KL600 is nonetheless the smoothest thumper we've ever ridden.

Next on the things-done-differently list is KACR, pronounced cacker, which stands for Kawasaki Automatic Compression Release. Almost every other four-stroke Single sporting an automatic compression release for easier starting has the device linked by cable to the kickstarter mechanism. The Kawasaki is different in that the KACR unit is mounted on the exhaust camshaft and comes into play only at cranking speeds. At those speeds, the centrifugally operated KACR opens the right exhaust valve one millimeter. This provides enough decompression to substantially reduce kicking effort. When the engine fires, the cam speeds up, the KACR retracts and the valve operates normally.

Still, despite all its new-fangled features, including KACR, the Kawasaki can be as difficult to start as the infamous big Singles of yesteryear. And just as with those motorcycles, there is a starting drill. If it's done right, the KL will fire in three kicks or less. Get it wrong and the KL acts like a two-wheeled Nautilus machine designed to develop leg muscles. The drill: Move the handlebar-mounted choke lever to the full-on position, do not, under any circumstances, touch the throttle, push slowly down on the kick start lever until some resistance is felt (that's the piston coming to top dead center), keep pushing slowly until the piston is just past TDC (the resistance will go away), let the kickstarter return to the top of its stroke, think good thoughts and, while wearing sturdy boots, kick the lever through. The drill worked well enough that by the end of the KL's test period, our testers were disappointed if the bike didn't start on the first or second kick.

Once running, the KL wasn't bothered by the stalling problems that plagued our XL600R or the mid-rpm stumble that persisted on our XT600. Credit here goes to the 40mm CV carburetor, which uses a flat slide rather than a standard round one. Kawasaki claims that the flat slide is lighter and takes up less room than a round slide. Engineers will also tell you that a flat-slide carb offers better atom-ization of the incoming fuel and, hence, better throttle response. Certainly, the KL's consistent, if slightly stunted, power characteristics bear out this claim.

Attached to the carburetor is a large plastic airbox that won no fans during our test. To get to the air filter, you must remove two screws holding the right sidepanel, then the panel itself, followed by four more screws that secure a door to the side of the airbox. The filter a flat, smallish panel of foam can then be slid out. Our test bike's filter wasn't sealing properly when we first got the machine, a situation remedied by the application of grease around the foam's edges. In addition, the airbox itself didn't ward off water all that well. After 45 minutes of splashing around in a shallow stream— more severe treatment than most dual-purpose owners will put their bikes through, admittedly—the air filter was wet enough to choke the engine. Wringing out the filter had us on the move again, though the KL wasn't very happy about the whole ordeal, and required a few miles of riding to dry out completely.

That the engine doesn't capitalize on its hi-tech credentials is a shame, because the rest of the motorcycle works well; in some instances much better than the competition. The seat, for example, is a good compromise between the

Honda's, which is too soft, and the Yamaha's, which is too hard. Together, the seat and the relatively smooth, relaxed power characteristics of the engine make the Kawasaki's KL the best choice for the dual-purpose owner who spends most of his riding time on the highway. Regardless of the terrain, all KL riders will appreciate the gearbox's slick shifting and properly spaced ratios as well as the bike's clutch, which survived its ordeal by test a lot better than those on some other dual-purpose bikes we've tested recently.

For riders with a preference for sporting backroads, the big Kawasaki is an able partner. It's no roadracer, but the standard dual-purpose traits of light weight (compared to that of most streetbikes) and virtually unlimited ground clearance allow the KL to negotiate a twisting section of asphalt with enough speed to embarrass more than a few knees-out riders on purebred sport machines. The only unsettling component in backroad adventures is the front disc brake. Though it's not lacking in stopping power, it gives little feedback to the rider and requires high effort at the lever. During braking tests, the best results were obtained when our rider pulled the brake lever in until it hit the handlebar grip. The drum rear brake provided adequate stopping power and predictable control.

The KL may be able to out-handle some road-only bikes on the street, but it'll never show its heels to a motocross or enduro bike off-road. That's to be expected. The KL is a lightweight on the street, but it is a bit heavy for serious trail riding. And while nine inches of suspension travel will soak up just about any road obstacle, it gets used up in a hurry when jumping a 325-pound motorcycle off of ledges and hopping it over rocks.

Not that the Kawasaki doesn't account well for itself in off-road situations. Remember its limitations and the bike will take you almost anywhere. Just don't expect to get through the rough stuff first with the least amount of effort when in the company of a real dirt bike.

Credit for the amount of dirt prowess that the KL does have belongs to the sturdy frame and compliant suspension. In talking with Kawasaki officials, we learned that the frame was originally designed as an open-cradle type a la the Yamaha XT Late in the development program, however, bottom frame tubes were added for increased rigidity. And if the rear of the frame looks like it was intended for an off-road racer, that's because many of the accompanying components were. The single rear shock, with adjustable spring preload and four-way adjustable rebound damping, is from last year's KX500 motocrosser, although the spring is softer and there is no remote oil reservoir. The Uni-Trak rising-rate rear suspension system attaches the shock to a beautifully crafted aluminum swing-arm that pivots on needle bearings and features eccentric chain adjusters. The eccentrics not only allow easy chain adjustment, but rotating the eccentrics 180 degrees effects slight changes in ride height (and thus, steering geometry) which can help speed up or slow down steering response.

The rear frame tubes that support the seat also show off-road heritage. Made of square-section, extruded aluminum tubing, the whole assembly attaches to the steel mainframe with four Allen-head bolts. Removable rear frame sections are popular with motocrossers because they allow easy access to the rear suspension when it comes time to clean, adjust or replace the shock. Most KL owners will never have to take off the frame section, but there's no denying that the nicely welded aluminum tubes do look stylish and probably are lighter than any steel counterparts.

At the other end of the bike, an air-cap-equipped fork assembly with 38mm stanchion tubes handles the suspension duties. Kawasaki recommends zero psi, however, as the best starting point. Like the rear shock, the fork is light on springing and bottoms easily when the bike is ridden very aggressively in the dirt. The KL could use slightly stiffer springs front and rear—not enough to ruin the bike's compliance to small street irregularities, but enough to give the bike more of a fighting chance in the rough.

Putting things in perspective, the Kawasaki KL600R is a dual-purpose motorcycle bristling with technological features, but it's nonetheless out of the horsepower hunt. That isn't as heavy a burden for the KL to bear as it might at first seem, because in all other aspects the Kawasaki can hold its own against the other big-bore street/trailers, if not do better.

Still, there's no getting around the fact that the Kawasaki gives away horsepower to the more established Honda and Yamaha. For the casual street-and-trail rider, that's not much of a problem. But for riders who like to pack all the fun they can into their rides, sooner or later the extra five horsepower is going to be wanted or needed; and getting that power if and when speed parts become available in the aftermarket is only going to widen the price gap between the KL and its competition.