2007 Kawasaki ZX-6R

  • MSRP: $8,999
  • Weight: 413 lbs (empty tank)
  • Weight Distribution: 49.8% F (w/full tank)
  • Peak HP: 97.7 @ 12,800 rpm
  • Peak Torque: 42.1 lb-ft @ 11,500 rpm
  • 1/4-mile: 10.77 @ 131.8 mph
  • Observed Fuel Economy: 36.4 mpg

This is the fifth year we’ve done this comparo, and during that time the Kawasaki ZX-6R has always had a unique personality. It was in 2003, the inaugural year of our Supersport Shootout, that Team Green thought outside the box and presented us with a 636cc 600, and the ZX has been the power king ever since.

But that distinction ends in 2007. Big K reps tell us that the cost of building a separate 599cc engine to race within the existing racing class structure no longer made good business sense, so the lusty 636 was put out to pasture.

Unfortunately for Kawi fans, the new engine makes news this time around as the weakest of the bunch in terms of peak power, unable to bust the 100-horsepower level on our stingy new dyno. As we noted in our ZX-6R – First Ride article, the electronic brain of American ZXs shuts the exhaust powervalve at high revs, effectively strangling the poor little gaffer by about 7 hp compared to European ZXs, according to Kawasaki data.

Even in its American state of tune, the motor is more impressive than its peak number might lead you to believe. It actually held its own in roll-on contests with the grunty CBR and it walked away from the GSX-R during a low-rpm roll-on. As a bonus, the soundtrack emanating from the small-block Kawi is a nasty wail.

“The new Kawi motor doesn’t quite have the kick of the CBR but it still feels pretty respectable, at least down low,” Chamberlain comments. “The midrange is decent and power delivery is pretty smooth. It seems to fall off a little on the top, but unless you were racing or riding it back to back with the other bikes, you probably wouldn’t notice.”

Unlike the CBR, the ZX’s throttle response couldn’t be smoother – off-throttle abruptness has been banished from this FI system. The command of a rider’s wrist is answered efficiently and without drama, leaving a rider’s brain free to concentrate on other pressing situations such as not running wide into that guardrail up ahead. This is a small but critical element to smooth and confident riding, and the Kawi does it best.

Also aiding confidence (while thumbing its nose to Honda) is the 6R’s excellent back-torque-limiting clutch. It casually accommodates even harsh downshifts, perhaps better than the others in the class. Combined with clutch take-up that is nice and easy to modulate for quick in-town sprints and a gearbox that operated flawlessly, the ZX got full marks in the Transmission/Clutch category – a first for a Kawasaki in our hands.

While Honda uses a steering damper to combat the CBR’s radical chassis geometry, Kawasaki has approached the handling formula from the other direction. The ZX eschews the need for a steering stabilizer by utilizing the most conservative geometry in the class. Its 25.0-degree rake is a full degree lazier than the next closest (R6), and its 110mm of trail is very generous compared to the sub-100mm numbers in the others. And its wheelbase is the only one that stretches beyond the 55-inch mark, a significant 1.5 inches longer than the sawed-off CBR.

“The ZX actually feels on par with the Honda, but it has different traits,” observes Kenny, adding that there are times when the ZX flicks into turns easier than the CBR.

Despite its sport-touringesque geometry, the Ninja received commendable scores in our handling categories, backing my claim after the bike’s intro that this is the best handling ZX yet. A rider is able to jump on the Kawi and immediately start cutting some quick laps. It has a cooperative chassis that holds no surprises, and the bike’s charitable amount of trail results in good feedback from the front end.

“While it isn’t as flickable as the Honda and Yamaha, it still turns in pretty quick,” states BC. “Once in the corner I found the bike very stable.” Fast-guy Roberti adds, “The front-end stability is awesome.”

The ZX-6R’s handling qualities became even more impressive after we found out what a chunky monkey Kawi has turned out this year. This is a trend team K started last year when the new ZX-10R gained 12 pounds in its makeover. With this new 6R, weight is up a massive 17 lbs more than last year! The ZX now scales in at the same weight as the first CBR600RR did five years ago, 413 lbs, which is 8 lbs more than a 400cc-larger ’05 ZX-10R. Perhaps the saddest stat of all is that the 2003 model ZX-6R weighed just 389 lbs, 24 lbs less than it does today. You’re going the wrong direction, boys! (How much would you like to bet the 2009 ZX has a magnesium valve cover and titanium exhaust?)

The Ninja also gets docked a few marks for coming up short in a few user-friendliness details. First, the engine is a tad cold-blooded, not wanting to accept throttle until warmed up a bit. Second, although we appreciate the highly readable tachometer and the small but useful gear-position indicator, we’re not so keen on losing a clock and dual tripmeters; a fuel gauge is obviously out of the question. Third, the mirrors offer the best view of your elbows. Fourth, the rear shock uses a locking-ring preload adjuster (like the GSX-R) instead of the easier to adjust ramped collar type, which makes it a hassle to alter. The suspension otherwise gets a fine score for being fairly supple for a sporting bike; separate high- and low-speed compression damping helps dial in the shock.

In normal street duty, the ZX’s riding position gets mixed reviews. A couple of testers complained about a bulky feeling from the long machine, but its cockpit and seat are a pleasant enough place to spend time and the ergos work well on both the street and track. Its fuel tank is a bit fatter than the others when sitting up against it, but it’s thinner when sitting back in a racer’s crouch.

Aside from an ill-fitting seat cowl, our crew was impressed with the fit and finish of the silver Ninja and its attention to detail. However, not all of us were sold on the bike’s new look, and a couple of us believed the bodywork looks too similar to the previous version.

“The ZX looks bland in contrast to the others,” Kenny critiques. “The big, flat surface of the side fairing will serve its purpose well with sponsor decals, but it just looks too vanilla for my taste.”

Overall, there’s a lot to like here, including its exemplary chassis, wonderful throttle response, slick transmission and clutch and its strong value for the $8,999 price tag. But we’d be lying if we didn’t think this would be a better bike with the power available from 636cc of displacement.

“Does the ZX miss those extra 37cc?” Kenny asks himself. “I say yes. On the street the ZX didn’t seem to be at a disadvantage, but when connecting turns at the track it seemed to be down a bit compared to both the R6 and CBR.”