2006 Kawasaki Ninja ZX-6R 636 Retro Review
Of all the classes and categories that exist in motorcycling, none is as hotly contested among motorcycle manufacturers as that of the supersports—the domain of the 2006 Kawasaki Ninja ZX-6R. Middleweight sportbikes represent the cornerstone of street-going product in the United States, with bragging rights and consumer demand driven directly by success on the racetrack. Winning an AMA Supersport Championship is a coveted and essential element to earning a piece of this all-important market share.
As a result, the title chase has become a gloves-off affair to create the best production-based 600cc sport machine. The clear winner in this annual gambit is the consumer, benefiting from the mercurial technological and engineering advancements driving manufacturers to win.
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Kawasaki currently holds the AMA Supersport Championship title, as well as the runner-up position, with its supreme ZX-6RR 600cc machine. In addition to the one-two punch on the track, Kawasaki—clearly marking its intentions to own the middleweight class—offers consumers an incremental edge over the competition with the ZX-6R 636. The addition of those 36cc, combined with 20 years of Ninja pedigree, have made the ZX-6R Kawasaki’s best-selling motorcycle.
Like its racing sibling, the ZX-6R is clearly aimed at hardcore sport riders while providing a user-friendlier street machine with the added bump in engine displacement and a wider-ratio transmission. The machine radiates confidence with striking good looks—born from the aerodynamic sensibilities of the wind tunnel—and extraordinary performance that come together to deliver a visceral wallop that’s impossible to dispute.
To allow the ZX-6R a proper forum to divulge its racing roots, we spent two full days screaming the machine around Spring Mountain Motor Resort and Country Club in Pahrump, Nev.
Delivering crisp yet smooth throttle response, the inline-4 powerplant performed well at low rpm, where its ample torque impresses for a supersport. However, the ZX-6R prefers to be wrung out and really starts to sing at the higher rev range, coming into its own well above 11,000 rpm.
Dual-stage EFI smoothes out the all-too-familiar hiccup encountered when rolling the throttle on from the fully closed position, and helps take the jerkiness out of getting back on the gas mid-corner. This makes negotiating a series of turns, which requires continual on-and-off throttle action—especially at lower speeds—a much easier experience. That should not be underestimated by the track day novice, and will be equally appreciated by track day experts.
Fully adjustable inverted 41mm Showa forks and Kawasaki’s linkage-assisted shock absorb the potholes and uneven pavement of real world street riding, as well as provide top level performance for track day outings. A claimed dry weight of 362 pounds, combined with a short wheelbase and a long, braced swingarm—a design borrowed directly from Kawasaki’s MotoGP bikes—results in nimble handling.
Whether under hard acceleration or during seriously aggressive braking, the machine stays composed. There is no twitching or chatter from either end; the Ninja ZX-6R is a solid, stable motorcycle.
The twin four-piston calipers are radial-mounted for positive on the 300mm discs. Feel at the extremely high braking forces encountered at racing speeds is excellent, yet they also deliver smooth, confident braking for everyday street riding.
The six-speed transmission has been refined and no longer has the disconcerting clunk that previously haunted shifts between first and second gears. In equal measure, the new gearbox allows the rider to find neutral with ease, something the previous year’s models had difficulty with.
The 2006 Kawasaki Ninja ZX-6R 636 comes standard with an impressive race-inspired slipper clutch. This back-torque limiting unit allows aggressive downshifts by automatically synchronizing rear wheel speed to engine rpm for smooth, progressive shifts while reducing the possibility of rear wheel hop or lockup. Again, this is a huge boon for both track day novices and experts.
Kawasaki engineers focused a good deal of their attention on the point of convergence. This is the area where divided air moving around the bodywork comes together behind the rider. Kawasaki designed an aerodynamically matched fairing and tail section that smoothly blends the invisible mass with less turbulence on the rider.
Once moving, the angular nose of the bodywork, with its sloped windscreen, combined with the pointed tail section and under-seat exhaust, ensures the ZX-6R pierces the unseen wall of atmosphere with maximum efficiency and minimal drag.
The cockpit of the 2006 Kawasaki Ninja ZX-6R takes its dimensions and ergonomic feel from its big brother, the ZX-10R, accommodating taller riders with a more spacious seat/handlebar/footpeg relationship. The steering head has been pulled back, reducing the rider’s reach to the handlebars, rendering a seating position that allows for more precise leverage and control.
The Kawasaki utilizes a dashboard instrumentation layout that combines a digital speedometer, LCD tachometer, temperature gauge, clock and tripmeter into a very compact unit tucked between the windscreen and top triple clamp. Overall instrument visibility for the rider is quite good, but readings on the LCD tachometer are difficult to discern in bright sunlight. Our preference would be for the more familiar separate instruments.
The ZX-6R is a comfortable mount with a healthy powerplant that makes for enjoyable street and canyon outings. Proving its embedded racing DNA—and Kawasaki’s clear intention for its use as a track day machine—the 636 comes with an adjustable shift indicator and lap timer. The shift indicator is easily visible in the lower peripheral vision, which helps the rider keep his eyes on the track, rather than counting revs on the tachometer at race speeds. The thumb-operated lap timer is an entertaining accessory, allowing you to monitor your progress on a circuit or, perhaps inadvertently, merely serving to humble you.
Either way, with the 2006 Kawasaki Ninja ZX-6R 636 beneath you, rest assured the ride is going to be very illuminating.
Photography by Mike Quindazzi
What rider doesn’t love a look back at the motorcycles that preceded today’s tech-savvy creations? Welcome to the Ultimate Motorcycling retro review archives; we’re revisiting some of our favorite reviews from year’s past, highlighting the machines that laid the rubber for what’s on the today’s showroom floors. Enjoy. – Ron Lieback, ed.