Kawasaki Kz650sr
KAWASAKI KZ650SR
CYCLE WORLD TEST
Two sincere cheers, please, for whoever it is at Kawasaki that invented and continues to supply an ongoing series of mildly modified production road bikes, in this case the KZ650SR. Cheers because this is a useful variation on an excellent basic model.
Only two cheers because some of the modifications are more flash than function.
The basic KZ650 is fairly well known. Introduced as a 1977 model, the 650 was supposed (and turned out) to be the size of a 500 with the punch of a 750. The new Kinglet set a flock of speed records and the dealers sold all the 650s they could get. The KZ version was and is mostly a scaleddown KZ1000; styled just like big brother, with a highly tuned and smaller dohc Four, wire w'heels, etc. The KZ1000 now' comes as standard, as the race-look Z-1R and as the custom LTD. In turn, the basic KZ650 has been supplemented by the Custom, with cast alloy wheels and triple disc brakes, and by the SR, with the disc brakes and the cast wheels and a bunch of other changes.
The differences between KZ and SR divide neatly into three classes:
Functional: Cast wheels, dual front and single rear disc brakes; 180°, 4-into-2 exhaust system, 16-in. rear wheel and fatter front and rear tires.
Functional and cosmetic; Longer, deeper seat, higher handlebars, shaped and smaller fuel tank.
Cosmetic: Chrome covers for the tachometer and speedometer, chrome covering for the chain guard, painted fenders.
As an adjunct, for the 1978 emissions standards the 650 engine for all models has 22mm carbs rather than the 24s of 1977. Because the SR’s smaller rear wheel increases engine speed to road speed, the rear sprocket has two fewer teeth. The rear tire also changes steering geometry. The frame is as before but the lower rear tire gives the SR a steering rake angle of 27.5° (compared to 27° for the KZ) and adds 0.25 in. of trail, 4.5 in. vs 4.25.
In mechanical terms, that’s pretty much the story. A deft touch here and there, a sure hand juggling the various parts and the Kawasaki store has another model on display.
Display. One eye on the mirror, as the song says. With the exceptions of you and us—and perhaps not even us—no rider can resist looking at the reflection of man and machine in the window'. We like to look good and we like to feel as if we’re looking good. The SR w ill accomplish this in the blink of an eye. Straddle the bike on the showroom floor and it feels just right. The bars and seat and pegs put you in a posture that can only be described as Swagger Sitting Down. The lowered rear and fat back tire have custom all over them, maybe even a hint of chopper, and the painted fenders, sleek tank and carefully balanced/unbalanced exhaust hint at road race. Nothing missing and it all feels right.
For the most part, with due allowance, it is right.
The engine is gains and losses. Most noticeable is the new set of smaller carbs. The '77 KZ650 had good power and a fat powerband but it also lagged just off idle. Instantly the throttles were cracked, the engine quit for a nanosecond and then caught, unless the rider had eased the clutch out. which killed the engine. Annoying and something we fiddled with until an advance curve from a KZ900 cured the glitch.
The 22mm carbs arrive w ithout a glitch. Never any hesitation, and still the same smooth power flow at partial and wide open throttle. Still on the good side, mpg improved just a bit. from 44 to 45.9. The smaller venturis flow less fuel and mix it better.
Now. The split exhaust system should, by the book, add power. A system which divides on the basis of timing, that is. alternate pulses equally spaced, can tune each pulse and provide an extractor effect. Most makers use a 4-into-2 system divided left and right, which looks symmetrical but delivers staggered pulses that do no good for the power at all.
That’s the book. The racing buffs were pleased to see the SR system. Hope w'as, the proper tuned exhaust would make up for the smaller carbs. The fat rear tire should improve starting line traction (it did) and the 650SR maybe would be as quick as the 1977 KZ650.
It wasn’t. Kawasaki built a quiet bike, with even a balance tube between the two halves of the system. The SR lacks the measured beat of the classic 180 exhaust and it didn’t bring back the power. The SR turned fractionally slower quarter mile times, 13.40 sec. to 13.19, and trap speed was dowm. 96.87 to 98.46 mph. Test weight is up by only 8 lb., surely the result of the extra brakes, so the factory’s listing of 2 less bhp is correct.
Odd thing, and one we would have forgotten but for the kind help of a factory-backed tuner:
The 180 system does not boost power in its production form because the muffling and baffling are so restrictive, Ahah. What do you suppose would happen in production class racing, where most of the sanctioning bodies allow' removal of muffler internals w hile requiring the outside of the exhaust to look stock? The 180 will increase power while the left/right 4-into-2 versions will just make noise. Do things like this happen by accident? No.
The loss is mostly in the mind, though, because the SR will show its heels to many 750s. just like last year, and the new' engine is easier to control.
The brakes are a clear improvement. Couple things here. The dual front discs and single rear disc total out to nearly three times the total swept area of the disc/ drum system. Fade obviously w ill not be a problem. And with all that area to work with, brake effort has been made more gradual, especially at the rear where the big tire has more contact patch and leverage has been juggled so the rider is less likely to lock things. Finally, stopping distances from 30 and 60 mph are shorter with the SR. The 8 added lb. is a bargain.
There may be a side effect. The dual discs are mounted aft of the stanchion tubes. The single disc rides in front. Moving the mass of the brakes this way adds to the self-centering forces of steering geometry.
This is mentioned because the SR does not handle exactly like the KZ650. Due to the other variations, i.e. increased rake angle, more trail and larger tires, pinning down the reasons for the handling differences is guesswork.
But they are there.
Motorcycle brands are like families in that the models are different while sharing certain traits.
In the case of Kawasaki handling, the KZ650 and KZ1000 share a quirk. On rough pavement, with frost heaves and patches, the front wheel tends to work around within the rider’s grasp, hunting back and forth. And the bike feels as if it’s falling into sharp turns, just at the instant the rider banks over and heads for the apex. Can’t say this is bad, in itself. A man who rides Kawasaki all the time won’t even notice. Another rider, though, switching to a KZ650 from, say, a Triumph or GS Suzuki, will go a mile or so and whip out the ol’ tire pressure gauge. Something feels funny.
Lane Campbell, our Inhouse Theoretician, writes that there are too many factors in handling response to allow a critic to point at Xo steering rake or Y in. of trail and proclaim, that’s why it does what it does.
However, the SR does have half a degree more rake and a quarter in. more trail and it does have the weight of the brakes working with self-centering force rather than against it.
And the SR does react less to ripples and bumps and it does give less of an impression that the initial bank into the turn was more than needed. Goes right where you point it, the SR does. Handling has always been a KZ650 strength, the same willingness as the big jobs but without the occasional flex or wobble, and the SR fits right in.
Also should say that the SR bars are six in. narrower than the KZ bars, and a couple inches higher as well, so the SR rider has less leverage and a shorter distance to move the control for a given input, while the height sits the rider higher and thus raises the center of gravity . . . let’s just say the SR is a good canyon cruiser.
Ride, though, is something else. Our 1977 report gave good marks to the KZ for its comfy ride. Perhaps because the lower tire reduces ground clearance, or because the engineers equate stiff springs w ith racing, the SR suspension is changed.
The forks have a lower spring rate. 25 in./lb. to 40. But the forks contain spacers to give ’way too much preload and the ride is, well, stiff. Bump-bump stiff. Shorter spacers are recommended.
The rear shocks/springs are the same. The specifications are changed, with a dual-rate spring replacing the straight rate units of 1977. But the softer portion is compressed by the pre-load, even on its softest setting, and thus what the rider mostly gets is the firmer portion of the spring. The ride is harsh. Again, trim back the preload and comfort will return.
Accommodations are a good example of how a motorcycle can be perfect for a few minutes and get less so after a couple hours in the saddle.
In the SR’s case, the saddle isn’t all the trouble. More like the combination of the various fittings.
One is mechanical, in that the neat little fuel tank doesn’t hold enough fuel. Stops are required every 120-140 miles or so, a bother on a long ride.
Also a relief. The high, narrow bars that feel just right at first sit the rider up straight. When you can’t lean into the wind, you must brace against it and that gets tiring. The pegs are forward, an inch or so in front of the rider’s midsection rather than directly below it. The seat is soft and properly shaped but the step plunks the rider in one spot and only that spot.
As a result, the SR does not wear well on a day’s cruise. One is forced into looking for alternatives, as when the feet ride on the engine case. As an extreme, one of our men found he could produce a useful counterfeit cafe style. Sitting on the aft portion of the seat puts the rider into a partial crouch and raises him into a better position for the bars. The passenger pegs then are in just the right place for feet, although one must plan ahead for rear brake and gearshift.
Oh. The absolutely clearest, least-contested gain of all the changes between KZ650 and SR is the passenger portion of the seat. Passengers just plain loved it. The KZ version is skimpy and crowded, for an adult, while the SR must have twice the padding and a few extra inches. The second person in all our two-up combinations thought it was the best they’d been on.
Okay, nobody at Kawasaki ever said the DR was for long weekends. For riders of the touring persuasion, Kawasaki offers a line of Vetter equipment.
What the KX650SR is, then, is a more specialized machine. The word would be custom except that a production custom is a contradiction in terms. The SR has style. The SR delivers a good profile. Considering that bikes run better after they’re washed, think how much better a bike runs when it makes the rider look good as he sits on it.
Meanwhile, no matter what the trim and tank and seat and bars, the SR is still a Kawasaki 650, top of the sporting middleweight class.
KAWASAKI
KZ650SR
SPECIFICATIONS
$2395
PERFORMANCE
FRONT FORKS
REAR SHOCKS
