2013 Kawasaki Ninja ZX-6R Review | Shrugging Convention

Is Kawi’s New “Cheater” the Ultimate Middleweight Streetbike?

While most of Japan's motorcycle manufacturers have taken the cautious approach to riding out the global recession—making minimal updates to existing models, building low-buck econobikes or otherwise hitting the snooze button—Kawasaki is wide awake with the throttle pinned. In the last three years we've seen a recession-defying number of new models. They include the ZX-10R, which remains the only open-class Japanese bike to have been completely reworked in the past 36 months, and was the first to come with traction control; the 2011 Ninja 1000, a reasonably priced sportbike for the real world; the 2012 ZX-14R, which simultaneously rehashed and squashed the decade-old horsepower feud with Suzuki's Hayabusa; the totally reworked 2012 Ninja 650; and the all-new, fuel-injected 2013 Ninja 300. And, finally, the 2013 Kawasaki Ninja ZX-6R.

The other industry players aren’t playing—especially in the middleweight category—leaving Team Green to make its own moves and build its idea of the ultimate middleweight. Just like a decade ago, Kawasaki is shrugging off class convention with a 636cc “cheater” motor. Unlike in 2003, Kawasaki isn’t building a 599cc version for roadracing. Kawasaki doesn’t care if there’s nowhere for the 636 to race, it’ll be a more versatile, user-friendly machine for street riders. That may put diehard sport riders on edge, but as the track-oriented press introduction proved (First Ride, Jan.) this Ninja is an even more capable track tool than ever before. And while the press event gave us a few hours on freshly paved mountain roads, we knew a longer, real-world road test was needed to fully evaluate this new bike.

We’ll get this over with early: Strapped to Motorcyclist’s SuperFlo dyno, the 2013 Kawasaki Ninja ZX-6R makes 112 horsepower at 13,300 rpm and 46.4 lb.-ft. of torque at 11,300 rpm. That’s up 3.3 bhp and 2.8 lb.-ft. compared to the 2012 bike in terms of peak power. Decent gains for a measly 37cc, but the midrange is where the new Ninja gets the most muscle. Between 5000 and 11,000 rpm, the new long-stroke 636 averages 5 more bhp than the 600, while the 2013 bike reaches the previous bike’s peak torque nearly 2000 rpm earlier.

That’s just what you glean from eyeballing the dyno charts. Ride the bike and you’ll swear the gains were greater. And it’s so smooth! Feed your average 600 a handful of throttle at a few thousand rpm and it will probably make more noise than thrust, or perhaps just strain or stumble. Not so with the Ninja. It pulls strong right off of idle with the most serene, fluid motor in the class. It’s driveable at all rpm, with an unexpectedly broad spread of power for a highly tuned, small-displacement four.

From the helm, this bike feels nearly as potent as a Suzuki GSX-R750. Editor in Chief Marc Cook was the first to make the comparison with the classic extra-middleweight benchmark. “The midrange pull feels as good as the 750’s,” says Cook. “It’s strong enough that you can almost ignore gear selection on a twisty road and just work on your lines.” Such flexibility makes for one accommodating and easy-to-enjoy motorcycle, no matter how you ride. But pure performance helps, too. Drag strip numbers show just how close the 636 is to the 750. The 2013 ZX-6R runs down the ¼-mile in 10.69 seconds at 129.24 mph, improbably close to the GSX-R750’s 10.44 sec. at 133.31 mph considering the Suzuki’s similar weight (it’s just 2 lbs. heavier) and superior power (a peak of 122 bhp). In top gear, the Ninja is only a tenth of a second slower from 60-80 mph, and actually 3/10ths faster from 80-100 mph. Granted, the Suzuki is held back by tall final gearing, but the fact that we’re making performance comparisons to the 750 and not to other 600s says a lot about the 636.

Kawasaki’s street focused updates are not just about horsepower and torque. The Ninja’s riding position is exactly as it was, but slight changes in chassis geometry—via reduced front ride height and increased rear ride height—put a little more weight on your wrists than before. The bars, seat and pegs are all in exactly the right place for sport riding, but the riding position isn’t too committed for the street, and is made unobjectionable by new, softer suspension that’s downright plush at the top of the stroke. The seat is soft (for a sportbike) and wind protection is adequate thanks to the well-contoured windscreen and revised fairing shape.

Kawasaki focused effort on lightening the bike’s feel by reducing steering resistance, accomplished with the installation of low-friction steering-head seals and removal of the steering damper. These changes pay big dividends on the street and at the track. The Ninja’s near-effortless steering makes the bike feel even lighter than last year’s model, despite a wet weight of 422 lbs., 2 up on the 2012 machine.

Rush hour traffic is the last place you’d expect a sportbike to shine, but in gridlock the Ninja gleams. While humanity is in a frenzy around you, the Kawasaki Ninja 636 rolls along unperturbed. Its stable chassis and ultra-light steering let you maintain balance at near-standstill speeds and carve your way through traffic with what seems like telepathic handling. New, more functional mirrors give a good view of surroundings aft, and there’s nary a hint of hot air to bake your backside or calves. Then there’s the Concours-caliber suspension that soaks up Botts’ dots and concrete seams, and while the transmission cogs feel like they’re bathed in butter and the clutch lever is as light as a feather, there’s rarely a need to work the shifter. How flexible? The engine pulls smoothly from as low as 2000 rpm in sixth. Abundant midrange power compels you to short-shift and leave the Ninja in a tall gear. It’s not uncommon to roll to a stop, only to look down and see an unexpectedly high gear position displayed on the dash. That’s the sort of thing you might expect to experience on Triumph’s super-torquey Daytona 675R triple, but not on a 600.

The only odd behavior the engine exhibits is upon start-up, where it occasionally idles just above stall speed for a few seconds. For the most part the motor is silky-smooth, but some high frequency vibes creep into the tank sides and grips above 8000 rpm. Top gear gets you 80 mph at 7500 rpm, so you can ride to work all week without ever experiencing a tingle, and when you punch it past eight grand in the canyons you’re unlikely to notice any discomfort, since you’re well into the Ninja’s impressive top-end rush by then. That means you have other things to consider, like when to apply the brakes for the next turn. Odds are you’ll pull the lever far too early; the 2013 Kawasaki Ninja ZX-6R’s new Nissin front brake setup is as good as any component combination from Italy, with a strong initial bite, tremendous power, and lots of feel. ABS is an option, adding $1000 to the $11,699 MSRP and a heap of confidence to your riding experience.

The previous Big Piston Fork was great for sport riding, but the shock faded when pushed, and as is typical of sportbikes, the setup felt somewhat stiff on the street. “Harsh” is not a word you could apply to the Ninja 636 under any circumstances. The suspension sucks all roughness out of imperfect roads while providing a clear summation of what the contact patches are encountering. Showa’s new Separate Function Fork Big Piston (SFF-BP) may sound like a translation mishap, but it and the revised shock are minor miracles in original equipment, with a level of compliance on par with a well-tuned touring rig. Yet the Ninja sacrifices nothing it terms of handling and feel. The relaxed showroom settings will eventually allow some chassis pitch and rear-end wallow when the pace picks up, but a few turns of the adjusters brings the handling back in line. The fork is especially easy to tinker with since all the adjusters are on the fork caps. There’s a flat blade in the tool kit for tuning the front and rear damping, but no spanner for setting preload. As it turns out, a quarter works great for setting the fork preload, but you’ll need the proper tool for the shock.

The minor changes in chassis geometry make the new Ninja steer sharper than before, but the bike is more stable than ever. “It gives you the feeling that you can tighten or change your line at any time for any reason.” says Cook. On the street as on the track, the Ninja is nothing but amicable. “It’s so easy to move around on,” says Editor at Large Aaron Frank. “I never felt like the chassis was arguing with me.” No combination of inputs could upset the chassis. If you can’t be smooth on the 636, you’re either trying way too hard or not at all.

Engine and chassis flexibility are just part of what makes the Ninja so versatile. Conditions change: those clouds may drain their watery contents on you, the road may become strewn with sand or you may just like to run your tires ‘til the cords show; the Kawasaki can accommodate via adjustable traction control and power modes that come as standard features. Both are tunable via the rocker switch on the left cluster. Push up to realize the 636’s full power or to experience a neutered, 90-bhp Ninja. Press and hold the rocker down to change the Kawasaki Traction Control (KTRC) setting. Your selection is indicated on the LCD screen to the right of the analog tachometer, which now positions redline at 16,000 rpm rather than 16,500 rpm as on the previous bike. KTRC makes the Low power mode superfluous, and as Associate Editor Zack Courts so aptly put it, “No self-respecting squid would be caught dead with his sick new 2013 Kawasaki Ninja ZX-6R 636 in Low mode.”

KTRC Level 1 is intended for sport riding, with maximum acceleration as its objective. It allows a fair amount of wheel spin, but the system works so smoothly that the only way you can tell it is functioning is by a slight warble in the exhaust note. Level 2 is more cautious, stymieing wheel spin that would otherwise go unnoticed by the rider. Level 3 is downright over-vigilant, eliminating any imbalance in front/rear wheel speed with a triple-punch spark/fuel/throttle butterfly combo. Level 1 is a good safety net on the track and Level 2 proved best in the wet, offering a high level of safety without limiting acceleration.

You may be ambivalent about traction control—some of us are—but when you’re navigating urban streets after dark in the rain, being able to dial in more safety with the push of a button is pretty fantastic. And with KTRC as a backstop, it was interesting to see just how hard you can accelerate in the wet before overwhelming the rear contact patch—the new Bridgestone S20s have inspiring grip.

For 2013, the Ninja’s shape is even more modern and edgy, with sharper lines that more closely parallel the ZX-10Rs. “I really loved the looks of this bike,” says Frank. “It has a lot of complex shapes, and looks carefully and functionally styled.” Fairing-integrated front turn signals preserve the Ninja’s sleek silhouette, but the painted plastic panels covering the upper frame spars are too much, and they showed scuffs after the first aggressive street ride. The black paint on the muffler makes it look down-market, but the can itself is slim and compliments the bike’s slender tail section.

There’s really not much to complain about. This year’s $1400 price hike—from $10,299 to $11,699 without ABS—is a surprise given the softness of the 600 Supersport category. But the updates justify the raise, though we’d love to have a standard quickshifter. As it is, the transmission is so slick that you hardly need one, but we can dream. Beyond that, the bike works so well and has had all flaws so thoroughly worked out of it that—dare we mention it?—it lacks personality. If you’re looking for charming quirks or amusing misbehavior, keep going. The Ninja is quiet (probably too quiet), smooth, and very relaxed. It’s a stone-faced performer.

Don’t misunderstand. Kawasaki’s emphasis on street-worthy performance is exactly right for today’s economic circumstances. Think of the Ninja as truly two bikes in one, a fantastically good track-day tool that will give you all the speed and capability you need, and a supremely confidence-inspiring street machine. The day of the hyperkinetic 600, a demanding witch of a motorcycle that challenges your skill, may well be behind us. So, yes, Kawasaki kicked convention to the curb with the 2013 Ninja ZX-6R, and in doing so built a bike that’s so good that it alone could breathe new life into the 600(ish) class.

Marc Cook
Editor In Chief
Age: 49
Height: 5'9"
Weight: 195 Lbs.
Inseam: 32 In.
I really thought I'd outgrown the 600 class thanks to the evergreen Suzuki GSX-R750. I've always loved that model, and owned one for quite awhile, so just call me biased. But I've long felt it bridged the gap between brutish literbikes and high-revving, torque-challenged 600s most effectively—the 750 combines the lightness of the traditional middleweight without the need to nanny the powerband every second. For me, that made the 750 a perfect real-world sportbike.

So much for that. The 636 feels every bit as strong in the midrange as the current GSX-R—in part because the Suzuki is geared quite tall—and is just as easy to use as a result. With modern electronics and the latest suspension, the 636 is the real sporting deal, beating the current GSX-R with pure competence. That you don’t have to ride it like you’re mad at it is all the difference in the world.

Aaron Frank
Editor At Large
Age: 38
Height: 5'7"
Weight: 155 Lbs.
Inseam: 32 In.
There are plenty of arbitrary reasons to build bikes to a specific displacement limit, like racing regulations or insurance cost tables. But there's no categorical rule that says 599cc is the optimum displacement for a middleweight sportbike. The Ninja ZX-6R shows how much benefit a bit of added displacement brings in terms of improved performance. And with the addition of traction control, power modes and optional ABS, the Kawasaki is an undeniably modern motorcycle. It's got a compact-yet-comfortable layout, ultra-neutral handling and impressive features that make it the complete sportbike package for 2013. Like Cook, I'm a former GSX-R750 owner but my decade-long love affair with that bike might be over.

Zack Courts
Associate Editor
Age: 29
Height: 6'2"
Weight: 185 Lbs.
Inseam: 34 In.
Make no mistake, this new ZX-6R is more than 37 additional cubic centimeters. If you think Ari is sipping the Kawasaki Kool-Aid and fawning too much over this new 636, think again. It really is an awesome package. Yes, the extra displacement helps, but it's the way it delivers power that is so impressive. The motor is endlessly willing, making power everywhere without a hint of a rattle in the fairing or a buzz in the pegs. It's docile around town, but exceptionally potent by the time the revs hit five digits. As if that weren't enough, the rest of the bike is an equal match. The brakes are superb, the ergos are comfy, and the electronics package is both tidy and useful.

The ZX-6R's new 636cc engine dishes up good stuff on the dyno, with power curves that follow a steeper, smoother trajectory than the previous 599cc version. Power falls off fast after 13,300 rpm, so short-shift to stay in the thick of it.

The 2013 Kawasaki Ninja ZX-6R 636 has the same ergonomic measurements as the 2009-2012 bike. Soft, well-damped suspension goes a long way toward making this sportbike tolerable for longer rides, while a reasonable rider triangle keeps you from feeling cramped.

Much More Than “Bold New Graphics”

The 2012 Ninja's frame worked so well—with a great balance of longitudinal stiffness and lateral flex—that Kawasaki saw no need to change it for 2013. The only differences are new mounting points for the updated fairing. As on the previous Ninja, the 2013 bike debuts a new fork design. Both legs of the Showa Separate Function Fork Big Piston (SFF-BP) contain springs, but preload is set solely via the left leg, while the damping circuitry is relegated to the right leg. The Big Piston design provides superior damping at the beginning of the stroke, while the Separate Function format simplifies tuning and saves a claimed 220 grams. A revised shock has a softer, longer spring with more progressive linkage for a smoother ride on the street. The Showa shock is fully adjustable, but doesn't have separate high- and low-speed compression tuning as on the previous model. Sliding the fork 2mm up in the new triple clamp reduces front ride height, while the longer shock jacks up the rear. Rake decreases from 24° to 23.5°, with sharper handing as a result. In an effort to lighten steering feel, Kawasaki removed the 2012 bike's Öhlins steering damper and installed new, low-friction steering-head bearing seals.

By far the biggest news with the new Ninja is its return to a 636cc engine, but that's just the start. In addition, all the engine's ancillary systems were tuned to support the displacement bump. The extra 37cc is achieved via a stroke increase of 2.6mm, for bore and stroke measurements of 67mm by 45.1mm. The engine uses shorter, stronger conrods to accommodate a longer crank throw, and the pistons' longer travel necessitated lowering the cylinder ports, which are in place to reduce pumping losses at high rpm. The camshafts were tuned to suit the stroke increase, with longer intake duration and a 0.2mm increase in intake- and exhaust-valve lift. The piston crowns were reshaped to make room for the valves' increased movement and to reduce compression slightly, which goes from 13.1:1 to 12.9:1. The 2013 Ninja ZX-6R now has an "assist and slipper" clutch, which uses a pair of cams to provide more positive engagement while accelerating, and controlled slip when downshifting. The design transfers load from the clutch hub and basket to the cams, allowing Kawasaki to make the inner hub out of aluminum instead of steel, and to reduce the number of clutch springs from six to three, for a total weight savings of 700g and a much lighter clutch lever pull. Throttle-body diameter remains the same at 38mm, but the 2012 bike's upper injectors were ditched in favor of larger, single, lower injectors. Deleting the upper nozzles allowed Kawasaki to increase the airbox volume by 11 percent, smoothing power delivery and boosting peak output. The move also made room for longer velocity stacks, which help with low-end performance. Most of what resides between the crankcases is the same as before, but first gear is shorter and all the cogs are thicker for increased durability. The retuned exhaust has balance pipes across all four headers, while a reshaped sub-chamber houses a shorter catalytic convertor. The new bike has a narrower yet longer muffler, made from steel rather than titanium as on the previous model. Redline was lowered from 16,500 to 16,000 rpm. The engine's measured output is 112 bhp at 13,300 rpm, and 46.4 lb.-ft. of torque at 11,300 rpm.

The 2013 Kawasaki ZX-6R raises the stakes in the middleweight class by offering comprehensive electronic rider aids. A hybrid traction-control package combines two sport settings culled from the ZX-10R's Sport Kawasaki Traction Control (S-KTRC) with a third, stability-oriented setting from the Concours' KTRC. Level 1 and 2 are meant to optimize acceleration and control tire spin and torque via ignition timing, while Level 3 combines ignition, fuel, and secondary throttle butterfly manipulation to totally eliminate any front/rear wheel speed differential in order to maintain perfect stability. Additional hardware includes front and rear sensors and associated wiring, but all the software magic is added to the existing ECU. The 6R also has two power modes: Full power is self explanatory, while Low maintains low-end and midrange performance but reduces peak output by 20 percent as well as softening throttle response. Other electronic updates include a new "Zero-Cross Control Voltage Regulator," which provides more consistent voltage to the bike's various electronic components and reduces electronic "noise," enabling more efficient operation and also meeting new European regulations. The optional Kawasaki Intelligent Braking System (KIBS) uses the same sensors as KTRC, plus a Nissin ABS unit that contains its own ECU.

The Ninja rolls on essentially the same six-spoke cast-aluminum wheels as before, albeit with a revised front hub to suit the new rotors and no green rim stripes. The wheels are shod with Bridgestone's new S20 hypersport tires, the successor to the BT-016s. The OE "J-spec" tires are different from standard S20s in terms of dimensions, and they're also slightly lighter. The Ninja's front petal rotors have grown 10mm, from 300mm to 310mm, to provide more stopping leverage. The rotors are also thinner (5mm instead of 6mm) to maintain the same weight as the 300mm discs. New, one-piece "monoblock" front calipers are more rigid than the previous two-piece units, and house four 32mm pistons each rather than a combination of 32mm and 30mm slides. The brake pad compound has been updated as well. At the rear, there's a smaller Nissin caliper with a single 30mm piston—the same setup as on the ZX-10R. KIBS is a $1000 option.

Why commit to a thorough mechanical and electronic update only to hide them under last year's clothes? Kawasaki didn't, so the 636 gets a nose-to-tail styling update. Up front, a larger intake duct fills the gap between the new projector-beam headlights, while new mirrors like those on the Ninja 300 project from a more slanted front fairing section that's said to have less drag and provide better wind protection for the rider's hands and shoulders. New integrated front turn signals preserve the Ninja's racey lines, while new body panels extend from the headstock on back to the tail, covering the upper frame spars in painted plastic. On the previous model you could see a radiator hose peaking through the fairing in front of the cylinder bank, but that's been addressed via revised routing that keeps the hose hidden. The previously-mentioned muffler is attractive enough to avoid being immediately replaced by an aftermarket part, and the tail section now houses an LED taillight.

Engine type l-c inline-four
Valve train DOHC, 16v
Displacement 636cc
Bore x stroke 67.0 x 45.1mm
Compression 12.9:1
Fuel system EFI
Clutch Wet, multi-plate slipper
Transmission 6-speed
Measured horsepower 112.0 bhp @ 13,300 rpm
Measured torque 46.4 lb.-ft. @ 11,300 rpm
Corrected ¼-mile 10.69 sec. @ 129.24 mph
Top-gear roll-on 60-80 mph 3.16 sec.
Fuel mileage (hi/low/avg.) 41/31/37 mpg
Frame Aluminum twin-spar
Front suspension Showa 41mm SFF-BP with adjustable spring preload, compression, and rebound damping
Rear suspension Showa shock with adjustable spring preload, compression, and rebound damping
Front brake Dual Nissin four-piston calipers, 310mm discs with ABS
Rear brake Nissin single-piston caliper, 220mm disc with ABS
Front tire 120/70ZR-17 Bridgestone S20
Rear tire 180/55ZR-17 Bridgestone S20
Rake/trail 23.5º/4.0 in.
Seat height 32.7 in.
Wheelbase 54.9 in.
Fuel capacity 4.5 gal.
Weight (tank full/empty) 422/395 lbs.
Colors Lime Green/Metallic Spark Black, Metallic Spark Black/Flat Ebony, Pearl Flat Stardust White/Flat Ebony
Available Now
Warranty 12 mo., unlimited mi.
Contact Kawasaki Motor Corp. 9950 Jeronimo Rd. Irvine, CA 92618 949.770.0400 www.kawasaki.com_


_ First Ride_ Gallery



_First Look_ Gallery


The 2013 Ninja 636 is in every way more capable and exciting than its predecessor. The extra displacement and chassis refinement have made it easier and more fun to ride.
The 2012 ZX-6R already had ferocious brakes. This year’s bike boasts even bigger calipers and discs for greater stopping power, but milder brake pads that reduce bite.
This is the same layout as before, but the tach face is black instead of white, and there are additional digital symbols corresponding to the 636’s new electronic features.