It's a bit more comfortable in the real world than the RR, but only a bit.

Make no mistake, this is still one kick-ass little sports bike – it squeezes out 100kW at a howling 14 000rpm (and revs on happily to 15 500 before the rev-limiter cuts in) at the expense of what I thought was quite a lot of secondary vibration, only to realise that it was actually the highest-frequency primary vibe I'd ever experienced.

As with all twin-spar framed bikes, the engine is part of the chassis and is bolted rigidly in place, hence any shakes in the mill are transmitted directly to the rider.

A reader pointed out to me that if this thing did have any secondary vibration, at around 516Hz you wouldn't feel it so much as hear it humming - about an octave above middle C on the piano.

No Cyril, it doesn't do that.

What it does is pull evenly, if rather gently, from 4000rpm, accelerating quickly enough to cut through the traffic on the freeway with smooth composure. At seven the engine comes alive, begins to vibrate and the twistgrip takes on a life of its own.

And from 10 500rpm on it howls at the moon, pulling harder than any 600 has a right to, filling the LCD rev-counter dial to the redline faster than you can say it. After 14 000 the power delivery flattens out and it's time for a (very) quick upshift if you want to stay in the meat of the powerband.

It hits the rev-limiter quite easily even in fifth; on my second top-end run I timed fifth gear by counting slowly "one-and-two-and-and-three-AND" and was rewarded with a momentary front-end shimmy as the bike tried to pull a power wheelie at 235km/h.

The ZX topped out about 1600m later at 259km/h with the engine spinning happily at 14 200rpm – three kays short of the best motoring.co.za has achieved with a middleweight, which was done at the end of a four-kilometre run with this bike's carburettor-fed ancestor.

Dual injectors

A good deal of the bike's superbly modulated power delivery is due to the 38mm Keihin throttle bodies with dual injectors and oval secondary valves controlled by the ECU; the hellatious top end, however, comes from the centrally mounted ram air intake, which routes the incoming charge straight past the steering stem into the airbox

For 2005 the ZX636 gets a slipper clutch to prevent the back wheel locking up under less-than-gentle downshifts; Kawasaki didn't tell me it was there until after I'd given the bike back so I didn't try anything radical with it.

In the conventional direction it's as bulletproof, predictable and well-mannered as Kawasaki clutches always are; the gearbox is also typically KHI, noisy at low revs and very positive, with a bit too much lash for comfort – which is why Kawasakis very rarely miss a shift.

By contrast there is very little lash in the final drive, thanks to a stiffer than usual cush drive in the rear hub.

The steering head angle is half a degree steeper at 25º than its 599cc stablemate; its wheelbase is 10mm shorter at 1390mm for more responsive handling at relatively sane speeds.

It works, too; the ZX changes direction neatly and accurately with a minimum of input from the rider. Even in heavy traffic – not this model's natural habitat – it steers lightly but without flopping into slow corners because there's no steering damper.

Unfortunately that leaves the bike vulnerable to disaster; exiting a garage on the N2 in the dark I hit a sequence of unmarked off-camber speed humps, put there to dissuade rapidly departing non-payers.

The resulting tank-slapper was one to remember; it says a lot for the inherent stability of the chassis that the little green machine didn't spit me off. Mr Engen has, however, permanently lost a customer.

Fully adjustable damping

41mm Showa upside-downies have replaced the previous Kayaba forks; their initial movement is easier, with less stiction, while the top-out springs and fully adjustable damping keep the front wheel under control all the time.

The front end of the bike always feels planted, giving confidence no matter how hard you pitch it in. In mid-corner, with the suspension fully settled, you can turn it on early and bring it out hauling like a freight locomotive.

The rising-rate rear suspension hardly squats but still shows very little tendency to patter on bumpy corners, mainly thanks to the Kawasaki's forward weight distribution. The test machine, however, had its rear ride height set at minimum; with a couple of spacers under the upper shock mount the bike will become distinctly more skittish.

Braking is entrusted to a pair of Tokico radial mount four-pot callipers acting on dual petal-shaped 300mm discs via a GP-style direct-action master cylinder.

Their action is unusually direct by modern standards, with very little lever movement before the action begins; once you get used to it, very fine brake control is possible – although I was a little disappointed to see all this hi-tech componentry connected by old-fashioned rubber hoses rather than modern braided stainless-steel.

Too-low screen

Kawasaki claims the best drag co-efficient in their class for the two ZX-6's; unfortunately that means, once again, a slightly too-low screen. It only works properly when you're crouched in go-for-it mode; sitting up normaly puts the slipstream straight into your face.

The upper edge of the screen also obscures the all-important top quadrant of the rev-counter (unless you're playing racer).

The instrument panel itself is the same as last year's, a compact and fiendishly efficient single LCD pod with a big digital speedometer, a coolant temperature gauge and a separate multi-function odometer, tripmeter, clock, lap timer, stopwatch and two-way shift warning light that comes on about 500rpm shy of the red line.

Ringing this module is the bar display rev-counter that's difficult to read at the best of times and fades into an even grey in certain low-light situations, even with the headlights on. Analogue instruments are heavier, more expensive and less accurate but they are easier to read at a glance.

The seat position has been moved slightly forward, based on research for the ZX-10R, to make the bike more comfortable and compensate for the extra weight of the Ducati-style, underseat exhaust.

As a result the ZX636 is not only one of the smallest bikes in its class but also the most comfortable on long rides and even in traffic – quite a achievement.

If you're a lover of agile middleweight race replicas but can't justify having a second bike just for weekend hooliganising – look at the ZX636. It'll take you to work all week and way out there on Sunday morning.