New ZX-6R a real-world road rocket

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2013 Kawasaki ZX-6R comes into its own where the roads are anything but straight.

Race bikes, even world championship-winning ones, do not always translate well to the street so Kawasaki, in production-engineering the ZX-6R that dominated the 2012 World Supersport series, has wisely chosen not to follow the purist route.

Thus the 2013 ZX-6R is first and foremost a streetbike, more race-derived than race-replica, with more power, more torque and less weight than its predecessor, and a state-of-the-art traction control system.

The new bike's engine has been upped to 636cc, thanks to a longer stroke of 45,1mm compared with the 600cc engine's 42,5mm, while bore size is unchanged at 67mm.

The extra 37cc capacity, along with revised ports, camshafts and new molybdenum-coated pistons, delivers an additional 2.2kW and 4.3Nm. In any case the 600cc limit on Supersport engine capacity only applies to racing so there's no need for road-riders to be restricted by it.

Kawasaki did the same thing from 2003 to 2006 with the 636cc ZX-6R - as did Triumph with the 2005 Daytona 650 - both of which were popular among street and track-day riders thanks to their bottom-end grunt and mid-range surge.

LEADING THE MIDWEIGHT STREET-BIKE CLASS

New 636cc Ninja is built to be ridden on the street.

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Thus the new Ninja ZX-6R leads the midweight streetbike class with 96.4kW (101 with ram-air effect) at 13 500revs and 71Nm at 10 800 rpm, while peak power arrives 500rpm and torque 1000rpm earlier than was the case with the 2012 ZX-6R's engine.

Kawasaki Heavy Industries is renowned as an engine-maker, so this one has to be tough - and it is, with shorter, stiffer connecting rods, larger radius small-end bearings, new gudgeon pins, an aluminium clutch hub that's not only stronger than the steel one it replaces but also 600g lighter, and wider gears in the transmission to cope with the extra torque.

The fuel injection system is new, breathing in through a bigger-volume airbox, the four header pipes are now joined to their neighbours to help create more torque, rather than simply linked in pairs as in the past, and a new, race-derived slipper clutch with assist cams reduces rear-wheel patter under engine braking, while providing a significantly lighter (Kawasaki says 20 percent) clutch pull than on the 2012 bike.

THIS BIKE HAS BRAINS AS WELL AS BRAWN

The traction control set-up on the new ZX-6R is derived from the KTRC system used on the current ZX-14R musclebike, rather than the Supersport racers, allowing the rider to choose between three modes.

The first two settings allow some wheelspin for maximum acceleration out of corners, as does the S-KTRC system of the ZX-10R, while the third, adapted from that of the 1400 GTR tourer, helps riders tip-toe across treacherous, slippery surfaces during bad weather.

However, the system doesn't behave like an interfering nanny when it comes to playtime; the first two settings allow controlled wheelies but will intervene if the front wheel comes up too quickly, to prevent a flip-over that would really spoil your day. In the third, most cautious mode wheelies just won't happen - or you can switch it off completely for track days.

QUICKER STEERING

The frame, sub-frame and swing-arm are essentially unchanged although rake has been slightly reduced for lighter handling; the forks now ride 2mm higher in the yokes, lowering the front end for quicker steering, and a new steering head set-up reduces friction for easier low-speed turn-in.

The Showa forks combine a separate function layout with fashionable big pistons; preload is adjusted on the left leg, while compression and rebound fettling are done on the right - and all the adjusters are at the top. The stanchion walls are also thinner - down from 2mm to 1.7mm - for a weight saving of 220g.

MORE SUPPLENESS AT SANE SPEEDS

The rear suspension for 2013 has a longer spring (up from 190mm to 215mm) with a softer spring rate and higher lever ratios for more suppleness at sane speeds on the road.

New Nissin monobloc front callipers are 45g each lighter than last year's (don't scoff, this is unsprung weight we're talking about here) on 310mm petal discs (slightly larger than before), while a dinky little Nissin single-piston calliper lifted straight from the ZX-10R parts bin grips a 220mm rear petal disc.

The body panels are all new, while the flight-deck instrumentation has been revised to include readouts for instant and average fuel consumption, traction control settings, a gear position indicator and shift light, coolant temperature, a clock and a low fuel warning light.

The 2013 Kawasaki ZX-6R will be in da house at your favourite Kawasaki dealer before Christmas; price, as always, when they get here.

SPECIFICATIONS

Engine: 636cc liquid-cooled transverse four.

Bore x stroke: 67 x 45.1mm.

Compression ratio: 12.9:1.

Valvegear: DOHC with four overhead valves per cylinder.

Power (with Ram Air effect): 96.4kW (101kW) at 13 500rpm.

Torque: 71Nm at 10 800.

Induction: Electronic fuel-injection with four 34mm Keihin oval throttle bodies.

Ignition: Digital electronic.

Starting: Electric.

Clutch: Cable-operated multiplate wet clutch.

Transmission: Six-speed constant-mesh gearbox with final drive by belt.

Front Suspension: 41mm inverted cartridge forks with top-out springs, adjustable for preload, compression and rebound damping.

Rear suspension: Bottom-link Uni-Trak linkage with gas-charged monoshock with top-out spring, adjustable for preload, compression and rebound damping.

Front brake: Dual 310mm semi-floating petal discs with Nissin radial-mount, opposed piston, four-pot callipers.

Rear brake: 220mm petal disc with Nissin single-piston floating calliper.

Front tyre: 120/70 - 17 tubeless.

Rear tyre: 180/55 - 17 tubeless.

Wheelbase: 1395mm.

Seat height: 830mm.

Kerb weight: 192kg.

Fuel tank: 17 litres.

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