The Motorbike Archives

Kawasaki first ventured into the customized field with the KZ900LTD, a bike with more flash than function. The LTD went for about $1000 more than the standard KZ900 and was considerably less versatile, albeit much more eye-catching. But with the limited-production KZ650 SR, the latest of Kawasaki's factory-built, custom-like boulevard buzzers, the company has created a flash-cycle which will provide pleasure for more than profiling. Although the 650 SR has received a full complement of chopper-esque styling touches from its wide, 16-inch, flat-black-and-polished alloy rear wheel to its bobbed and pin-striped front fender, the stylists apparently remembered that after the ogling is over, someone has to actually ride the motorcycle.

For example, consider comfort, one of the most-often sacrificed aspects of semi-chopped boulevard cruisers. Look at the SR's carefully styled seat which recalls Triumph customs and yet still complements the Harley-like suggestions in the tank and rear wheel. When you're done looking, you can climb on and know that it will be over two hours before the saddle even begins to feel stiff. The handlebar looks right but isn't radical enough to ever cramp your arms or bend them at awkward angles. The lean-look front fork glides smoothly over most bumps and the rear shocks keep the ride comfortable, too. Only the short front fender reflects a comfort compromise for styling, and then it's noticeable only on wet streets where more water than usual is thrown up by the front tire.

The only real comfort concern is a minor one that isn't related to the custom flavor of the KZ650 SR. The mild vibration which buzzes the handlebar noticeably and blurs the mirrors slightly at highway speeds is subdued enough that just wearing heavy gloves will muffle it.

The tiny, peanut-shaped fuel tanks on most customized street machines go well with the theme of short-range comfort. But the SR's distinctive fuel tank offers a 3.8-gallon capacity, only .7 gallons less (about 27 miles less range) than the standard KZ650. The SR's tank permits the rider to go about 120 miles at our average of 38.5 mpg before he has to fish for reserve. That's enough gas to span the gaps between even the most remote gas stations and to get farther than most riders will choose to go without a break, even on a bike as comfortable as the SR. A few miles before you must switch to reserve, a "Fuel" light in the tach glows until you refill.

The SR uses the same 652.1-cc doubleoverhead-cam four-cylinder four-stroke engine as the standard KZ650. The internal specifications are identical, as is the hank of 22-mm Mikuni slide/needle carburetors. The torque and horsepower charts in the 650 shop manual claim that the SR has fractionally less power than the standard KZ, although the only difference between the two is the SR's 360-degree, crossover-style exhaust system. This system should deliver more power than the standard pipes, but evidently it doesn't.

The power difference is not perceptible in actual riding, however. If anything, the SR comes off as a better performer than the KZ. The engine makes excellent wide-range power and it's easy to ride with very little gearshifting. Despite a slight lag in throttle response when the throttle was suddenly pegged at cruising speeds, our KZ650 pulled away from a Suzuki GS750 in fifth-gear and fourth-gear roll-on acceleration contests starting at 50 mph. The SR doesn't have as much peak horsepower as the GS750, which the Suzuki demonstrated by pulling away when both machines began accelerating against each other in third gear at highway speed. But the Kawasaki has easily obtained acceleration for passing and more convenient power when dealing with city traffic.

At the dragstrip, the SR was almost four tenths of a second quicker and over two mph faster than the KZ we tested in December 1976. The difference was almost certainly due to the SR's 16-inch rear tire with its big, wide footprint. The extra rubber on the road prevented excessive wheelspin and provided more drive for a best run of 13.06 seconds with a top speed of 100.1 mph. We also suspect that the fat rear donut will last longer than the comparatively skinny 18-inch tires used on the back wheels of most big street bikes.

The fat rear tire doesn't make the bike track differently in corners. but it may be responsible for the Kawasaki's pronounced rain-groove wiggle. Both of the SR's tires grip the pavement well, although the lower height of the rear of the bike caused by the shorter rear tire contributes to the SR's slight lack of cornering ground clearance when compared to the standard 650 four. Even so, the SR offers reasonable cornering clearance, and the folding footpegs are the first thing to grind, followed by the centerstand on the left.

The SR's suspension offers a comfortable ride, but it's not 'quite as good in serious swoops and bends as most other current suspension systems. With 1500 miles on the odometer, the rear shocks on our machine were beginning to show the first signs of fading away. The minor suspension shortcomings probably contributed to the only quirk we noticed during fast cornering. If subjected to a sudden change in suspension load or if whipped quickly from one side to the other in a tight essbend, the SR would sometimes react with a small, unalarming twitch. Despite a very slight pogo-stick behavior in the suspension when cornering aggressively, the 650 was stable, precise and predictable.

The center of gravity isn't too high, so the SR may be pitched into a corner with very little effort. In spite of the minor increase in rake and trail which came about when the rear of the bike was lowered from the standard bike's specs by the 16-inch tire, the SR was also easy to ride at low speeds. where steering was still quite light. What's more, surprisingly little exertion was required to lift the 482-pound machine onto its centerstand.

Although the dual-disc front brake is almost certainly fitted for its visual appeal, it's also a much more effective (although heavier) stopper than the standard KZ's single-disc front brake. The dual-disc setup is controllable, progressive, fade-free and powerful. That power enables the rider to lock the front wheel at any speed, but never unexpectedly.

The rear wheel's single disc is also capable of locking up the rear wheel, and on a bike with a narrower rear tire the brake would be too easy to lock unexpectedly. This is another instance where that wide, chopper-style rear tire and wheel improves the bike's performance, since the tire has enough traction to keep the brake from overpowering it. The power of both brakes and the rear tire's traction enabled the SR to screech to better-than-average controlled-condition stops and quick, controllable panic stops in traffic.

Riders who buy the KZ650 SR to show it off at burger emporiums will probably be disappointed if theirs, like ours, seeps oil and develops a layer of mung around the base gasket and crankcase breather. Still, even though the bike smoked during the minute or so of choke-on warm-up which was required every morning, we never had to add oil. One chain adjustment was necessary during the first 1000 miles, hut no other maintenance was required.

Despite the SR's macho appearance, the bike has an ineffective horn which sounds like it belongs on a moped. Fortunately, the lighting engineers were more safety-conscious than those who chose the horn. Honda-style always-on running lights incorporated into the front turn signals make the bike much easier to see and identify in nighttime traffic and help keep drivers from overlooking the bike and cutting it off. The four-way flashers also make the SR more visible when necessary.

We're always mildly aggravated by Kawasaki's starter interlock, which requires the clutch lever to be pulled in before the electric starter will operate. This is intended to prevent inattentive riders—who don't check to see if the bike is in neutral before starting—from punching the starter button while the bike is in gear and on the side-stand, thereby causing the machine to lunge forward and topple over. Unfortunately, Kawasaki's system misses the point. An inattentive rider will just get in the habit of grabbing the clutch lever when he walks up to the bike to start it. Then unless he checks for neutral, the bike will lurch forward off the sidestand when the engine starts and the clutch lever is released. What's more, since the rider has to hold the clutch lever while the engine is cranking, he can't play with the choke lever to find its optimum setting during cold starts. He has to release the clutch lever, re-set the choke, then grab the clutch again. And if he has something like a helmet in his hand when he walks up to the bike he has to put it down before he can start up.

The SR's clutch disengages with a light pull and engages smoothly and progressively during normal starts. However when subjected to full-throttle, high-rpm starts the clutch would grab and make a groaning sound.

The well-staged five-speed transmission functioned perfectly. Shifts were light, and it was impossible to find false neutrals, even when we tried. However, locating the real neutral when we wanted it was easy with Kawasaki's automatic neutral finder. When the 650 is at a stop, it won't upshift past neutral after you select first gear. Once rolling, the bike shifts normally again.

Heavy styling treatments are nothing new, even on Japanese bikes. The mid-sixties street-scramblers, for example, were more styling than function. What is new is a heavily-styled street-custom which hasn't forgotten function in an effort to raise its stare ratio. The Kawasaki KZ650 SR is not only as good, as practical and as complete as its less-striking standard counterpart, it's functionally better in some important ways, like its rear tire, dual-disc front brake and maintenance-free cast wheels. And at $2395, the extra features and flash of the SR will set the buyer back just $470 more than the standard KZ650.

We suspect that the KZ650 SR will attract buyers mostly because of its custom appearance and its promise of prowess on the cruising circuit. But the owner won't regret his choice when he decides to cut a few hot ones on a meandering back road or when he heads across the country on a summer tour. The Kawasaki KZ650 SR is undeniably a good-looker, made for turning heads and showing off. But more importantly, it's also a terrific all-around motorcycle.

TECH PROBE

A customized motorcycle is supposed to be a personal statement made by its owner. If that's really true, designing a mass-produced custom bike must be about as analytical as a fast and loose game of Pin-the-Tail-On-the-Donkey.

From the outset, the basic concept is a contradiction in terms. A motorcycle that is identical in every respect to thousands of others rolling off the same assembly line certainly can't make a statement of a very personal nature. And unlike the one-of-a-kind bikes hand-built by individual riders, a factory-designed custom cannot violate the laws governing motorcycle equipment or even encroach upon the intent of those laws. The machine must be built well within certain legal engineering parameters. And that stipulation automatically keeps designers from venturing very far from conventional limits.

Bearing those facts in mind, it should come as no surprise that the KZ650 SR really isn't a custom in the purest sense of the word. It is a limited-production motorcycle that offers a few features one might see on a real custom, accompanied by a number of other pieces that make the bike look different from the standard model. But more to the point, the SR is aimed at a specific type of rider, a person who would like to own and ride a fairly individualized bike but hasn't the time, the equipment, the ability or the inclination to build one himself. So if he's willing to sacrifice his demands for total individuality, Kawasaki can supply him with two models that almost fit his specification. One of those bikes is the KZ1000. LTD. The other is the KZ650 SR.

Scratch the SR more than skin-deep and you'll find a regular KZ650 lurking beneath the surface. The engine, the entire frame and most of the suspension pieces are standard KZ650, as are virtually all the internal pieces.

The engine is an air-cooled, four-stroke, double-overhead-cam four displacing 652 cc. The bore/stroke relationship is oversquare, which simply means that the 62-mm bore is wider than the 54-mm stroke is long. The compression ratio is 9.5:1, rather high by current street-bike standards, but Kawasaki nevertheless okays the use of unleaded gas.

The 650's dual cams push directly on the ends of its valves without the aid of any rocker arms. This is a common arrangement on twin-cam motorcycle, engines. The 650 is the only bike engine, however, in which the shims used for adjusting the valve lash are housed under the tappet cup atop each valve stem. Usually these shims are held in a special recess on the top of each cup. Kawasaki's experience with valve adjustment is definitely more difficult than with conventional screw-type rocker-arm adjusters, but it can be done without removing the cams. Because of the valve shim installation in the 650, the cams must be removed so you can get at the shims to change the valve clearance. And that means re-timing the cams and fiddling with the endless cam chain when you're done adjusting. It's not the kind of a job a rider would want to try in his driveway. Actually, it's not the kind of a job an average rider would want to try at all, which means his bike must visit a dealership to have the valve lash corrected. Thankfully, KZ650s have demonstrated an ability to go a long way between valve adjustments, so the valve-shim problem should not be encountered more frequently than every 10,000 miles or so.

The 650 gets its sparks from a conventional dual-point, dual-coil, battery-ignition system. The points are opened by a single-lobe cam driven by the right end of the crankshaft. A flyweight-type mechanical advance built into the cam advances the ignition spark as the rpm rises.

Although there is nothing wrong with breaker-point ignitions, they do need periodic adjustment and component replacement. Yet there are some bikes that have maintenance-free ignitions as standard equipment–either points-free capacitive-discharge or transistor-controlled systems. And when you consider the maintenance requirements of breaker-point ignition, the complicated valve adjustment and the synchronization of four 22-mm Mikunis, the KZ650 earns the dubious honor of being motorcycling's most difficult and time-consuming four-cylinder engine when tune-up time arrives.

All is not lost on the maintenance front, however; the KZ650's crankshaft, connecting rods and all its crank bearings are cheap to replace or repair. Some big fours use one-piece crankshafts and split-type plain bearings all around. Others have built-up, pressed-together cranks fitted with roller and needle bearings. The KZ650 uses a plain crank, just as rugged as the roller type, that runs a little more quietly and, perhaps best of all, is less expensive to repair. Roller cranks usually must be replaced as a unit–bearings, flywheels, connecting rods and all–but just one bearing or rod of a plain crank can be replaced. And completely overhauling it is much cheaper than with the roller style.►