Last season Kawasaki upped the ante in the traditional middleweight class with a long-stroke 636cc version of its Inline Four-powered Ninja ZX-6R ($11,699). The formula proved a winner—but this time the green bike lines up against a couple of bigger, newer machines—but are they faster?
Even though Kawasaki touts its 636-powered Ninja as an improved street mount, it continues to pay dividends on track. Like the other machines, the green bike feels svelte. Because it shares the same type of four-cylinder architecture as the Suzuki, ergonomics feel very similar, if not a pinch more assertive, which the majority of our testers preferred.
Since it employs the smallest engine size, it’s no surprise that it weighs the least too, 424 pounds ready-to-ride. That’s three pounds under the lightweight Suzuki, four less than the MV and 13 fewer than the 899.
The combination of a low rolling weight, along with its more modest, yet rider-friendly powerband is a recipe for success and the Kawasaki required the least amount of energy to ride quickly.
“It’s a very easy bike to ride fast,” thinks Neuer. “I felt like a hero riding that thing.”
“It’s a very easy bike to go fast on,” echoed Pridmore, who set his third-fastest time on the Ninja during Superpole (1’50.46)—only 0.03 of a second slower than the GSX-R750, but 0.8 second away from the substantially more powerful F3. “Very plush feel—doesn’t do anything wrong. It’s a great, great, not only street bike, but a great track bike.”
For comparison, the Ninja posted the second-fastest time for the author (1’53.14)—0.10 second ahead of his fast lap on the MV. But it trailed the more powerful Suzuki by 0.18 second. These times are even more impressive considering it is the only motorcycle not equipped with an electronic quickshifter. Though, to be fair, because of its plump mid-range and optimum gearing the Kawasaki’s gearbox was the one we had to work the least. But when we did, we were pleased by its precise feel between cogs; so much that it earned full points in the Drivetrain category.
(Top) Although the Ninja doesn’t come equipped with a quickshifter, its optimum gearing and crisp-shifting gearbox allowed it to rank higher than the models that had the extra electronics. (Center) The Ninja’s traction control system functions well but because of its smooth, linear powerband it doesn’t really need it on high-grip track/tires. (Below) The Ninja’s monobloc-style calipers from Nissin were rated superior to the Brembos on the other bikes.
Although it weighs the least, the ZX wasn’t the most responsive during turn-in with it feeling close to the Suzuki, if not a hair sharper. Through the slower, second-gear right-left transition of Turns 8/9 the Kawasaki recorded the second-best flick rate behind the F3. However, in the faster third-gear Turn 11/12 switchback it tied the 899 for the slowest measurement.
“The Kawasaki was very similar in the way it changed directions to the Suzuki,” thought Neuer. “But there were a lot less mistakes for me on the Kawasaki. It’s just so good on the brakes and into the corner, I just felt like I was carrying more speed than the other bikes.”
In terms of corner speed, the ZX-6R was consistently quick through each of the three sectors. Sure, it wasn’t the fastest, but it wasn’t the slowest either. When averaged, it ranked 0.3 mph behind the class-leading F3 and GSX-R and 0.1 mph ahead of the Panigale.
Like the Suzuki, the chassis didn’t offer the sharp road feel of the European bikes. That could be the reason why it recorded the lowest maximum lean angle through the banked, right-hand bowl. The issue stems from Kawasaki’s decision to fit a more street-oriented fork, which while offering a crazy wide range of adjustment, it’s missing that firm precise-damping feel of the others. Hence the low score in this category, even though the front suspension didn’t do anything wrong, per-se.
“The suspension is a little soft feeling,” admits Neuer. “But it is just nit picking at this point. I think it’s an excellent motorcycle.”
“The ZX-636 is the best chassis on track, today,” thinks Northover. “It’s just really nice to ride.”
Off corners we appreciated how well the Ninja put power to pavement. Despite not having the sheer muscle of the others, the Ninja’s powerband was highly effective and rated second only to the MV. At the exit of Turns 10 and 13, it registered acceleration force numbers ahead of the high-strung Ducati proving its value even though it is significantly down on power.
Preload: 11 (Turns in)
Compression: 5.5 (Turns out)
Height: 8mm spacer
Preload: 6 (Turns in from stock)
Engine Power: Full
In fact, it’d be easy to write off the Kawasaki based on the results from dyno testing. It produces the least peak torque and horsepower, 48.35 lb-ft at 11,000 revs, and 114.34 ponies at 13,300 rpm, respectively. Look closer at the torque graph, and you’ll notice its broad curve, which helps it keep pace with the other machines during corner exit.
Still, there’s no denying how flat the Ninja’s motor falls off up top. That’s the reason why it posted the slowest top speeds down the back straightaway (127.8 mph—5.6 mph behind the GSX-R) and off the bowl (121 mph, which trailed the Suzuki by 4.4 mph). Still, Neuer claimed he could go quicker on it.
“To me I felt like I could go the fastest,” he said. “It doesn’t have the sheer muscle out of the corner as the other bikes but when it came down to sheer lap time the Kawasaki felt the fastest.”
Lower top speeds meant we didn’t have to apply the brakes
(Top) The Ninja’s ergonomics were rated the highest overall. (Center) The underpowered ZX-6R keeps pace with the competition via its broad and highly-effective powerband. (Below) The Ninja’s chassis feels dull mid-corner, but it still function impeccably with excellent road holding.
as hard entering corners. Yet, the green bike generated higher braking forces than the Ducati. Again, this could be attributed to the reduced engine braking effect of its smaller Inline Four motor. While it didn’t post the highest G-force (MV) our testers preferred the firm and responsive feel of the Kawasaki’s Nissin monoblocs compared to the oppositions Brembos.
It proved difficult to get an accurate read on the Kawi’s factory-equipped and wheel-speed enabled traction control system. Not because it was difficult to use or did anything wrong, but due to the superb grip of the Pirelli Diablo race tires. This along with a mellower-feeling motor made it nearly impossible to get any hint of wheel spin. But like the GSX-R’s aftermarket Bazzaz set-up and the Ducati’s black box, the ZX’s electronics never felt like it held the bike back during full throttle acceleration.
Even though it isn’t the most powerful, the lightweight Ninja remains competitive through the combination of its broad midrange and optimum gearing allowing it to drive hard off turns. Add in class-leading brakes, track-focused ergonomics and the Ninja has the right ingredients for quick lap times. True, its suspension lacks the super firm damping and road feel of the other brands, beyond that gripe it’s nearly faultless. Mid-pack scores in a number of the performance categories kept it a distant second, but in light of the competition’s muscle it makes the Kawasaki’s showing that much more impressive.
- Highly effective powerband
- Drives hard off corners
- Class-leading brakes
- Fork feels vague
- Top-end power falls off quickly
- Could steer sharper
Engine: 636cc liquid-cooled Inline Four, DOHC
Bore x Stroke: 67.0 x 45.1mm
Compression Ratio: 12.9:1
Fueling: Fuel-injection, 38mm Keihin throttle bodies
Transmission: Six-speed cassette-type
Clutch: Wet, F.C.C. w/ cable actuation
Final Drive: Chain; 16/43 gearing
Front Suspension: 41mm Showa BP-SFF with spring preload, compression, and rebound damping adjustment; 4.7 in. travel
Rear Suspension: Uni-Trak equipped gas-charged shock with spring preload, compression, and rebound damping adjustment; 5.3 in. travel
Front Brakes: 310mm petal discs, radial-mount monobloc-style four-piston Nissin calipers
Rear Brake: Single 220mm petal disc, single-piston Nissin caliper
Tires: Bridgestone Battlax S20 120/70R17, 180/55R17
Curb Weight: 424 lbs
Wheelbase: 54.9 in.
Rake: 23.5 deg. Trail: 4.0 in.
Seat Height: 32.7 in.
Fuel Tank: 4.5 gal.
MSRP: $11,699 ($12,699 with ABS)
Colors: Pearl Flat Stardust White; Flat Ebony Metallic Spark Black; Flat Ebony Lime Green
Warranty: One year, unlimited mileage