Kawasaki Z 750E

Horsepower rules. A philosophy which gives rise to such excesses as eight-litre automobile engines and 250 horsepower marine outboards. Never mind that most giant-engined American cars came with crossply tyres (albeit whitewalled), slushy suspension, vague steering and jamtin drum brakes. And never mind that giant, six-cylinder, two-stroke (to keep the weight down) outboards consume more fuel than a bulldozer with the choke on. Power is all, bigger is better and biggest is best.
Or is it? Motorcycling is about more than straight roads and obesity exacts a high price in handling, not to mention under brakes and at the petrol bowser. It even takes the edge off acceleration, the attribute most dear to those who revel in brute power and care for nothing else.

Weight is especially important in two wheeling, far more so than in tintop-ping or other transport modes. The single most-cherished aspect of motorcycling  machine response — is diminished directly with each extra kilogram. The real heavyweights are invariably clumsy, awkWard and ponderous compared to what they might have been, although clever engineering can disguise the ill-effects.
TWO WHEELS has long recognised this fact (our 1980 Bike of The Year was the lean Yamaha XJ650) as have the famous European bike builders. But the Japanese have been slow catching on. To date anyway.
Certainly there has been the odd lightish model from Japan, though these were not usually slender in the European sense, but follow-up models often saw such a return of flab it was obvious the temporary shortage of mass was coincidence rather than deliberate design. Suzuki's GSX750 is a case in point. The first Oriental motorcycle to break this pattern good and proper was last year's XJ650 and the signs are that Japan's big four have at last seen the (excuse pun) light.

Oddly enough, the second genuine lightweight out of Japan is a product of Kawasaki Heavy Industries, the same
manufacturer who pushed the pendulum just that little bit further the opposite weigh, sorry, way, than anyone else with its jumbo 1300 six. And just to show what can be accomplished when a motorcycle is put on a serious diet, Kawasaki has come up with the lightest, fastest accelerating, most economical 750 we've ever tested. It's also fun to ride, easy to handle, not too complex mechanically and keenly priced. Not bad for the least powerful 750 from the Land of the Rising Sun!
The bike Kawasaki aimed for an optimum power to weight ratio with their new model, and since the engine was to be based on an overbored Z650 four rather than a whiz bang four-valves-a-pot newie, there was a limit to power at the outset. So the fat had to be carefully pared, and pared, and pared. The final result, much to the big K's credit, is a Z750 which weighs 9 kg (20 lbs) less than the Z650! At 210 kg, the Z750 is 26kg lighter than Hondas  CB750K 16 valver and 24 kg below Suzuki's GSX750  handy advantages indeed. Yamaha's XJ650, at 204 kg, undercuts the Z slightly, but if one straddles both bikes and rocks them it's the Z which actually appears the lighter.

Aiding the lack of mass are a low seat height and a low centre of gravity. The Z750's frame is basically the same as the Z650's, save two minor details — the engine was relocated slightly to improve high speed stability and the top two frame rails were lowered 20 mm to reduce the seat height.

Suspension of course had to be upgraded for the Eighties and the Z750 comes with air-assisted forks and adjustable damping rear shock absorbers, both from Kayaba. Cornering clearance is increased over the 650, the three drilled disc brakes use Kawasaki's sintered metal pads for improved wet weather stopping and the old tungsten headlight and puny, single horn soldier on.

Other additions for the new model include electronic ignition, tamper-resistant brake fluid reservoirs (you need a Phillips head screwdriver to tamper now), an ignition switch steering lock, hazard lights, a stepped seat you may not like and a positive neutral finder you will like. On the debit side, the styling is dated (although the bike is far from ugly), the colour drab (subdued might be kinder) and the instrumentation is in need of updating.

A voltmeter has been added for the Z750, but we'd prefer an oil temperature gauge on a highly tuned, plain-bearing four without an oil cooler. Outback temperatures get very high in summer and the 750 is certainly a tourable motorcycle. Final drive is by roller chain rather than the more convenient shaft of Yamaha's XJ.

Engine

Beyond any doubt, the Z750 is endowed with an outstanding power-plant. Based on Kawasaki's 652 cm3 four it may be, but this 738 cm3 version delivers such hearty performance it's almost impossible to believe the two are from the same mould. And not only is the larger engine's performance up, on TWO WHEELS' test figures its economy is significantly improved too.

Starting with the Z650 four, Kawasaki increased the bore size 4 mm to 66 mm, leaving the stroke at 54 mm. A reworked head using 1 mm bigger inlet and 2 mm larger exhaust valves was also developed and this, together with new pistons, resulted in a 9.0:1 compression ratio for the new engine. Claimed power is now 55.2 kW (74 hp) at 9000 rpm, measured at the engine crankshaft.

Helping the new head and bigger pistons do their thing are a quartet of 34 mm constant vacuum Keihins (not, as most magazines will tell you, Mikunis), the largest carbs on any Japanese 750 by the way, and a pair of less restrictive silencers. The new mufflers are slightly growlier at idle and low to midrange revs, but didn't seem any noisier at peak revs.

This means the bike is a shade louder than the Z650 in around town running, which to our minds is a, good thing. So many whisper-quiet bikes are now emanating from Japan that careless car drivers will soon be able to add "I just didn't hear him, Officer" to the usual "I just didn't see him, Officer".

The little bit of extra road presence is nice, and perhaps a few less Z750 owners will feel the need to buy a (probably too noisy) four-into-one.
Other changes for the 750 motor include a beefed up clutch, an automatic camchain tensioner, a silent "Hy-Vo" camchain (in lieu of the 650's roller camchain), a larger alternator (output up 21 percent) and slightly taller gearing.

The engine is finished in black with contrasting polished alloy covers (a la Z1000s) and is generally designed to minimise regular maintenance although the cams must still be removed to adjust valve clearances.
In use, the engine is a delight — it starts easily (what doesn't these days?), is extremely smooth and free spinning (the mirrors blur at freeway speeds but the rider is unaffected), responds in microseconds, never showed any signs of overheating and never needed an oil top-up.

The Z750 produced such good torque at low revs that little warmup time was needed before riding off and the choke could be pushed home very early in the piece. Both of our test bikes, one with 9500 km on the clock, the other with 200 km up, were noisier mechanically than we expected, es-
Top

The Z750 is a nimble bike, and is let down by oversprung rear suspension in only the roughest, bumpiest corners.
Left — Forks are air assisted and provide a good adjustment range. Bike steers very well.
Below — Traditional styling suits the traditional virtues of the bike.
pecially given the new silent cam-chains, but this was only noticeable at idle and didn't annoy in any way.
Engine braking, while strong at high revs seemed less than most 750s at low to medium engine speeds, although this was in keeping with the very free-revving powerplant. The willing motor spins effortlessly to 10,000 rpm in the lower four gears and indeed that engine speed was found the best to change-up on at Castlereagh drag-strip.

Fuel consumption has taken on a new importance but Z750 buyers have less to fear than most 500 cm3 and over bike owners. The Z is the first really high performance 750 (it is, as we shall see, the fastest 750 on the market) which has averaged better than 50 miles per gallon on a TWO WHEELS test, the closest to date being Honda's 16-valve CB750K with a 15.9 km/litre (45.2 mpg) average.

 The old Z650 with far less power than this 750 and Yamaha's shaftdrive XJ650 both averaged 15.9 km/litre as well, primarily because both bikes need to be revved fairly hard if the rider is in any sort of hurry.
For the record our test Z750 (the loose one) averaged 18.6 km/litre (52.9 mpg) on test, producing a touring best of 21.1 km/litre (60.0 mpg) and a hard riding average of 14.8 km/litre (42.1 mpg) in road use. Consumption during the 42 km of dragstrip testing was 11.1 km/litre (31.6 mpg) although this is not considered in our "hard riding" or test average figures since the use is so extreme.

By far the biggest factor in the excellent fuel economy of the 750 is the lack of need to drop gears to obtain decent acceleration. The engine is incredibly torquey at low revs — the "powerband" seems to extend from idle to redline — and the light Z750 virtually pours on the km/h the instant the throttle is opened (unless one is in a totally unsuitable gear). It really is surprising how fast this Kawasaki will go without resorting to abnormal, banzai riding styles. This good low-rev-power/light weight relationship also means the Z has megabike type instant pickup available for accident-dodging manoeuvres should you ever require it. A definite primary safety plus.

Performance

To answer the questions you're all asking first, the Z750 gobbled up Castlereagh Dragstrip in 12.4 seconds at 172 km/h (several times), topped out at a true 204 km/h (though the speedo would have you believe it was 215 km/h), pulled 41.7 kW at 9500 rpm on Stewart's dyno and peak torqued at 42.8 Nm at 9000 rpm.
That all makes the new Z the fastest accelerating and fastest top-ending 750 money can buy, by a couple of tenths over the quarter and a couple of km/h absolute. But that's the unimportant part of the story! The important part is how the new four does it and that is with cool, relaxed ease. Nothing we did on the Z750 was hard work, the bike helped the rider all the time and drag-strip testing and top speed runs were as hassle-free as a ride to the corner shop for some milk. The bike's supremely predictable power delivery and smooth engine response to the throttle made dialling in just the right power at Castlereagh easy in the same way the Z's steady feel at high speeds made top speed testing a secure experience.
What the absolutes don't show and what is of prime importance to street riders is the engine's flexibility. The Z750's engine is without doubt the most flexible 750 powerplant we've ever come across. A glance at the dyno curves will show what we mean — the torque curve is virtually flat all the way from 3000 rpm to 9500 rpm except for the small blip upwards from 8000 to 9000 rpm. Were it not for this mild end hump (which is caused by a slight extra pickup in the power curve just before its peak), maximum torque could easily be at 3500 rpm, a very low speed indeed although our test Triumph 750 Bonneville had its peak torque at 2000 rpm.

This remarkable torque spread shows best the Z's strength at low crankshaft speeds although comparing its power at low revs with that of its rivals is interesting too. It is worth noting as well that even if the Z made only the same power at low revs as the
Honda and Suzuki fours, the bike would still feel a good deal zippier because of its substantial weight advantage. But of course it makes more and responds even harder because of it. Expect the low-rev pickup of a lively one-litre bike and you won't be too wide of the mark.
The Z750 makes about 25 percent more power at 3000 rpm than Honda's sixteen valve 750, which we commended in its test for making more power at low revs than the old single overhead cam 736 cm3 fours did. This is to say the Z's power to weight ratio at 3000 rpm is about 30 percent (nearly a third) higher than the 16-valve Honda CB750K's. No wonder its low speed pickup is so strong! We haven't dynoed Suzuki's GSX750 yet, but from riding the bike we'd say the Suzi TSCC engine makes a shade less low rev power than the Honda, but a little more top end power.
Needless to say the bike behaved faultlessly at all times during the performance testing — no blueing of pipes or clutch-slip troubles at all.

Transmission

Straight-cut primary gears transfer power to the beefed up clutch and then through a normal five-speed constant-mesh gearbox and endless secondary chain to the driving wheel. Kawasaki has included a positive neutral finder on the Z750 but this works a little differently to the one fitted on one-litre Kawas. The ZI000's neutral finder is in fact a positive neutral stop between 2nd and 1st gear on the way down through the box and allows normal, upward 1-2 changes. The Z750's neutral stop is between 1st and 2nd on the way up the gears, but it only operates when the bike is stationary and a normal, one step 1-2 change occurs when the bike is mobile.

Overall gearing is excellent, the Z750 almost pulls redline revs in fifth at top speed and the internal ratios are evenly spaced and sensible. There is a touch more drivetrain lash than we'd like, but less than most Hondas suffer from and we're not complaining. The clutch lever has a mildly firm pull but the operation of the clutch itself is faultless.
The only transmission area we'd like to see improved is the operation of the shift linkages themselves. Because of the engine's relocation and the more rearward footpeg placement on the Z750, Kawasaki has used a small repeater linkage to connect the new gearlever to the gearshift mechanism operating shaft. The result is a long-travel, vague-feel gear lever which needs a lot more effort than it should. Mind you, the box itself is quite positive in its engagement and this masks the linkage problem.

The toe-bar of the gearlever is made of rod that's too thin and the placement of the lever relative to natural foot/ankle angles seems poorly thought out. The footbrake lever suffered a similar malady, one always seemed to have to move the right foot deliberately outwards, upwards, inwards and then down onto the pedal. Playing with the adjustments helped a little but we thought both the brake and gear levers were too close to the pegs. And the double gear linkage seemed too spindly and fragile, most un-Kawasaki-like.
Oh yeah — both of our testbikes had a fair quantity of drivetrain whine. We're told its normal (like the XJ650's), but it's still there.

Handling, steering and suspension

Steering is superb and handling is very good. The Z750 is Kawasaki's best offering in these areas for some years. The steering particularly is state of the art. One sits into the Z and the bike feels right to the rider in the same way, but perhaps not to quite the same extent, as Yamaha's brilliant XJ650.
Nimbleness is the name of the game and riders stepping off heavier bikes may need a day or so to adjust their riding styles to the more sensitive Z750 before being able to appreciate the model's talents. Persevere, for the rewards are worth the effort, the Z is an excellent all round handler with one minor proviso — its performance on rough, bumpy bends is not as good as, it might be because the rear units are somewhat oversprung. The air-spring forks are excellent and provide a useful adjustment range (8.5 to 13 psi or from quite plush to racily firm) whereas the rear units work well two-up on their softest setting but jar the rider and allow the back wheel to hop about too much one-up, even with the rebound damping adjusted up. The absorbent forks and oversprung rear end made an odd match, we thought.

Nonetheless the bike is basically a forgiving mount, secure one- or two-up and easily able to cope with midcorner braking or line changes. Flicking the Z through S-bends is pure exhilaration — it feels more like a 400 than a full-blooded superbike.
Ride comfort for the rider is passable despite the heavy rear springs and tightish knee bends but pillions don't fare as well. They actually sit behind the shock absorber's top mountings and cop a fair pounding from road bumps as the pillion seat is less well shaped than the rider's and both portions of the stepped seat could use a bit more padding. Indeed, the passenger perches so far back on the short-wheelbased but long-seated Z750 that he becomes a definite aid in monowheeling — we encountered three or four two-up wheelies while we had the Z, but only one (deliberate) solo wheelie. The seat cover, while it looks nice, is made from ridiculously slippery vinyl.

No complaints at all with the braking (aside from footpedal location), we found the stoppers reliable, powerful and as fade free as most. Stopping distances were good, as was feel at the controls and we like the good-looking, all-black, rectangular fluid reservoir for the front discs with its screw-down lid and clear sightglass. A nice anti-vandalism touch although we don't know anyone who's had their front brake sabotaged. Still, kids might be deterred.
General

The fuel tank's capacity is rather less than some 750s at 17.3 Litres , but the thrifty Z stretches this out to a reasonable touring range so no demerit marks here. Reserve is a smallish 1.7 Litres , though. Switches are standard Kawasaki units (manual blinkers only) and do the job satisfactorily, which is more than can be said for our testbike's speedo which was (excuse pun) miles out. It read 11 percent high at 60 km/h (an indicated 60 is a true 53.3 km/h), 8 percent high at 100 km/h (100 equals true 92) and was only 5 percent high at 200 km/h (200 equals true 190). Entirely unsatisfactory although, strangely enough, the odometer was only 2.2 percent out when we checked it prior to calculating true fuel consumptions.
We didn't think much of the rearview mirrors, so-so blinker units, lousy helmet holder, ugly rear mudguard, under-padded seat and so on but we loved the engine (oil leak from head and all) and 99 percent of the rest of the bike (like the handy wet weather gear pocket under the hinged seat).

Conclusion

Kawasaki has taken the bit between its teeth and shown it will cater for all tastes — those who want silky smooth, six-cylinder, battlecruiser-cum-tourers and those who want genuine lightweight high performance sportsters. This augurs well for the company's future as well as our future as motorcycle buyers.
We liked the Z750 and what it represents (a return to basics) in spite of one or two shortcomings and the 1981 model with its snappier paint schemes and new, more padded, less slippery seat promises to be better again. The rear shocks? They're easily changed along with the tyres. — CM.
Right — Slim, light and potent are the words that immediately come to mind about the mill. Header pipes tuck in neatly, too. Below — Kawasaki has produced a definite winner with the Z750. Traditional virtues such as lightness and a flat torque curve are matched by very good handling

Source Two Wheels 1981