2008 Kawasaki ZX-10R - Street Afterthought

Even in this day and age of sportbikes boasting performance that's barely a step away from the racetrack, manufacturers have still spent a significant amount of time making sure their sporting machines have acceptable street manners. After all, the majority of sportbikes still rarely ever see racetrack tarmac, so making an effort to prevent the casual street rider from being too uncomfortable or overwhelmed seems like basic business sense.

But when we asked project leader Yasuhisa Okabe how much racing influenced development of the '08 Kawasaki ZX-10R, he quickly revealed, "All of the ZX-10R's development took place on the racing circuit. Every change we made was for superior performance on the circuit first. All else was of secondary importance." Surely there were some alterations made for the street rider? "Hmm," he murmured, actually having to think hard about it. "Very little. Not much." Well, OK, then . . . guess that answers that question.

As if to reinforce that point, Kawasaki held its world press launch of the new ZX-10R at the Losail International Circuit in Qatar, where the opening event of the MotoGP season has been held the past three years. Two straight days of continuous racetrack lapping on a world-class circuit would reveal if the significant changes made to Kawasaki's literbike flagship had indeed improved its all-out performance. Qatar being situated out in the middle of the desert, good sportbike roads were obviously nonexistent, so street riding was out of the question.

Big Changes
The design concept behind the new ZX-10R was to create the "ideal superbike racer [with engine and chassis performance to satisfy professional riders], which was then adapted into a high-level street-going model that could also be enjoyed by mid-level riders." The engine modifications were extensive, aimed at not only more power but also improved control for the rider. Details can be found in the engine/chassis tech sidebar (page 34), but a brief overview shows that while the bore and stroke remain the same, very few engine components escaped the engineers' CAD/CAM knife. Biggest changes include dual injectors/oval subthrottle bodies, a new cylinder head, higher-lift cams, a 1kg-lighter crankshaft (with the same inertia by redesigned counterweights), a larger airbox and a reshaped ram-air duct.

The engine component that probably garners the most attention, though, is the new Kawasaki Ignition Management System (KIMS), which monitors various engine parameters and prevents spikes in engine rpm during acceleration (translated as wheelspin). However, despite initial appearances the KIMS is not a true traction-control system in a performance sense (see the KIMS sidebar, page 36, for more details).

An elevated level of feedback to the rider was high on the list in the chassis development. While externally looking nearly identical to the previous unit, the twin-spar aluminum frame has been extensively revamped, with numerous changes intended to alter chassis rigidity in differing areas. Brakes and suspension received some upgrades, and even the ergos on the new ZX-10R were intended to improve feedback by increasing the number and size of the areas on the bike that come in contact with the rider while cornering. Check out the engine/chassis sidebar for the lowdown on the changes for 2008.

Overall styling of the new Ninja is obviously leaning toward the minimalist trend in MotoGP, where less surface area helps reduce the bike's susceptibility to sidewinds, as well as theoretically helping flickability at speed. The twin-underseat-exhaust styling trend is apparently dying fast, the '08 ZX-10R joining the under-engine chamber exhaust movement with a single orthogonal titanium silencer protruding from below the right side of the engine. Unfortunately the new exhaust is the main contributor to the additional eight pounds over the previous ZX-10R.

Track Daze
For the two days of lapping at Losail International Circuit, Kawasaki outfitted the new ZX-10Rs we rode with Pirelli Diablo Supercorsa DOT race rubber. In an effort to display just how race-ready the new Kawasaki is, the first day was run on the standard off-the-rack Diablo Supercorsas, while the second day was run on a track-specific version (the World Supersport Championship has an event at Qatar, so Pirelli developed a tire especially for the track requirements) for even better traction on the tricky circuit. We were informed that American ZX-10Rs will come equipped with the new Bridgestone BT-016, the company's latest sport radial, which will replace the BT-014.

It was probably due to the Pirellis' taller profile that the new Kawasaki's ergos felt different. The rear end's raised ride height made the bars feel lower, but when I asked Okabe-san about it he said the ergo measurements are identical to the previous model. The seat is definitely narrower at the front, which makes the bike feel narrower, but the top of the fuel tank is flared out slightly to allow more contact with the rider's arm when leaned over, so the bike initially looks wider from the saddle.

Any impressions of large size immediately fade away once you begin to up the pace and flick the bike into a corner for the first time. The new ZX-10R steers much lighter with a much easier initial turn-in than the old model, especially in the faster turns. And this is despite the newer Kawasaki having more relaxed steering geometry and a nearly one-inch-longer wheelbase compared with the previous edition (25.5-degree versus 24.5- degree rake angle, 110mm versus 102mm trail and a 55.7-inch versus 54.7-inch wheelbase). While some of this could be attributed to the DOT race tires fitted, it's enough of a difference that the race rubber couldn't be responsible for all of the new Ninja's nimbleness. There weren't really any places that were rough enough to tax the Kawasaki's stability, but we never encountered a hint of instability during two days of track riding.

Steering characteristics overall are nice and neutral (although again, we'll have to wait until we ride the bike on the stock Bridgestones for a final verdict) and very precise. Front-end feedback is also improved, and while some of that could be attributed to the DOT race rubber there's no doubt the increased trail helps in that regard.

One area where we had issues with the old ZX-10R was in the rear suspension department. The previous engine was definitely not lacking in steam, and its tremendous power potential tended to cause a lot of chassis pitch, especially squatting under hard acceleration. Attempting to tighten up the rear suspension to counter the squat tendency forced too many compromises with compliance, causing rear tire grip problems. Thankfully the new ZX-10R's rear-suspension-linkage ratio is more progressive with a better-matched spring rate, which helps keep the rear suspension from reacting too much to the engine power. We know the word "balanced" has been overused lately when describing current sportbike chassis, but the new Kawasaki's overall feel simply fits that description better than any previous ZX-10R in the past.