2003 Kawasaki ZX-6R/R: A Look Back

It's interesting to see how much the 600cc supersports playing field has changed in the last four or five years.

While the Honda CBR held the mantle of best sports six for the latter part of the 80s and early 90s, Suzuki's Gixxer and then Yammy's R6 have subsequently taken over as the most desirable.

Of course, much of the reason for this is that they're well 'ard, with Yamaha and Suzuki forgoing some on-road niceties in favour of more highly-strung track tools.

And now you have the likes of both Kawasaki and Honda selling two seemingly similar 600cc supersport bikes, in order to compete both on the road and on the track with their brethren from the Nihon.

While the CBRF4i is quite a piece of work, it's GP-inspired CBR600RR cousin is a more serious proposition, though opinion is still divided between the Ninja duo... But more on that later.

Both new Kawasaki's, the ZX-6R and ZX-6RR, share the same fairings and many internals too.

While they can insult the senses when you first lay eyes on them, we really like the agro new look.

It's a bit of an 'up-yours' at conservatism, and it works a treat.

The tail's sharp as they come, the new ram-air intake similarly aggressive (and likely to be a love or hate aspect of design) and the headlight cluster is supremely radical.

The screen is now lower than the 2001-2002 model, the tank slimmer, and the general riding position isn't so much a jack-of-all-trades style - more a purposeful 'I'm here to rack up demerit points' riding position.

The new styling implies a much harder attitude, and Kawasaki seems to have backed this up in the engine department.

The ZX-6R gets a new 636cc powerplant, while the ZX-6RR gets a 598cc mill, in order to comply with FIM, AMA and various other racing commitee regulations.

Early reports suggest that while RR has a few nifty doodads, like the limited slip system installed in the RR's clutch, aimed at preventing rear wheel lock on aggressive downshifts, the standard R represents better value.

According to Kawasaki however, this won't matter, because all 30 ZX-6RR's coming to Australia are accounted for. Natch.

Both bikes are nearly identical, save for engine capacity, but for those lucky few who manage to get their hands on the RR, here's a list of extras:

• lightweight forged pistons

• 13:1 compression ratio

• adjustable slipper clutch

• radial brakes

• three position adjustable swingarm pivot

• frame-mounted steering damper boss

While there are engine components carried over from the superceded model to the '03 ZX-6R, it is pretty much an all-new beast, boasting an almost 10 per cent boost in power.

Kawasaki reckon a good deal of the new engine's increased go is due to introduction of fuel injection, now standard across the 600cc class.

Making use of 38mm throttle bodies (with sub-throttles atop reshaped 10mm shorter intake tracts), the injection mapping is controlled by a rather tasty 32-bit CPU, which gives more precise engine management.

Lighter and much shorter plug-mounted ignition coils are used, with increased trigger numbers on the pulser rotor. In laymans terms, this equates to more precise ignition timing.

The cylinder and heads have been upgraded, with the latter shortened by 10mm and camshaft design has been tweeked to suit higher rpm and to accommodate cam timing changes via slotted cam sprockets.

While the R and RR have different sized engines, both make use of the same all aluminum cylinders with chrome composite plating.

The RR gets the aforementioned forged pistons, though the R's cast pistons now have improved cooling jets and narrower rings compared to the outgoing '02 bike.

While the Kwaka 600's engine has always been strong, gearing for both bikes has been given a solid kick in the pants.

Both bikes share the same gear ratios, and all but first and second gears have been shortened for better acceleration in higher gears. The RR gets a special slipper clutch, which makes use of variable thickness spring retainers and shims, while the ZX-6R gets a multi-disc wet clutch.

Both engines are liquid-cooled, DOHC, 16-valve inline four-cylinder mills, with the 636cc engine from the ZX-6R makes a claimed 87kW of power @ 13,000rpm, and some 91.5kW (125bhp) when the effect of ram air is factored in. Peak torque hits @ 11,000rpm: 67Nm to be precise.

With a dry weight of just 161kg, arguably one of the lightest Ninja's yet, it wouldn't be hard to break 3.0 seconds in the 0-100km/h sprint.

The new centrally-mounted ram air system passes directly though the frame, but this in no way reduces torsional rigidity. According to Kawasaki: "All-new, all-aluminium perimeter frame offers exceptional strength and rigidity while delivering crisp and stable handling performance."

Judging from early reports, it ain't lying either, as the new Kwaka is supposedly quite the nimble performer. The new frame locates the swingarm pivot further forward, which will improve rear suspension action, and the swingarm is also longer than last years model.

Suspension-wise, the ZX-6R uses sexy gold-anodised, fully adjustable 41mm inverted Kayaba front forks, while top-out springs are fitted for stable performance throughout the stroke range. At the rear, a race-bred Uni-Trak rear suspension rig will help put power to the ground, a nitrogen gas-charged rear shock with piggyback reservoir is fully adjustable for rebound/compression damping and preload.

Damping rates have been adjusted front and rear for a more planted and firm ride, plus a top-out spring has also added to the rear shock for improved action.

280mm twin discs up front, mated to 4-pot calipers, haul the new Ninja in from speed, while a smaller 220mm single rear disc rounds out the braking package. The RR model gets radial-mounted, 4-piston front brake calipers - a is a first for a 600cc production bike. Four independent brake pads are used - one for each piston - which helps keep wear and heat to a minimum.

To keep you posted of important telemetry, a new all-digital instrumentation cluster offers up a plethora of info, and looks very suave, to boot.

There's the digital speedometer, LCD tachometer, digital trip meter, odometer, water temp readout, clock, shift indicator light and an onboard lap timer. Speaking of suave, new energy efficient LED tail lights are now part of the package as well.

New wheels front and rear are lighter, which helps reduce unsprung weight, while a colour-coded rear-wheel hugger helps keeps the crap off the rear shock and looks cool too.

Kawasaki has gone back to the drawing board, done its homework and put in the hard yards: The result of which is an astounding all-new 600 Ninja. The ZX-6R is a finely-tuned piece of kit, more dedicated to putting in the quickest lap times than any other 600 Ninja before it, but will street riding suffer as a result?

Sure, the looks are guaranteed to turn a few heads, but it's more the sum of its parts that impress. The new engine, improved suspension and stiffer frame all contribute to what will be one the finest track tools in Australia.

Perhaps the GSX-R600 and R6 are no longer the kings of the hill?