As a Japanese OEM, Kawasaki has never been one to be shy. The company has a long history of groundbreaking motorcycles that not only set new standards for performance, but are also remembered for their audacity. Many of these bikes basically threw convention out the window, and made their own rules when it came to class warfare. The H1 500 and H2 750 three-cylinder two-strokes, the original 1972 Z1, the turbocharged Z1R TC of 1978 and 1983 GPz750 Turbo, the 1984 Ninja 900 and 600R of 1985…the list goes on.
Kawasaki has been continuing that maverick streak lately, with the ZX-14R laying waste to the competition last year by dint of an 89cc increase in displacement. And that philosophy continues for 2013, with both the Ninja 250R and ZX-6R receiving boosts in engine size. While the ZX-6R makes a return to the 636cc displacement (ridden elsewhere in this issue by associate editor Bradley Adams) popularized by the 2003-2006 models, we also got the opportunity to sample the all-new Ninja 300 — Kawasaki’s answer to the incursion of its 250cc territory by Honda’s CBR250R.
Kawasaki chose the mountains bordering the famous northern California wine region of Sonoma County to demonstrate the new Ninja 300’s performance to the American press. The numerous twisty roads in the area provided a superb proving ground to see if Kawasaki’s upgraded lightweight class machine indeed had the goods to go with its new moniker.
Bigger, Stronger, Faster
We brushed over the basics of the new Ninja 300’s technical details in the last issue, but Kawasaki revealed a lot more during the tech briefings at the press intro. As we noted before, the Ninja 300 engine gets its 47cc displacement increase via a whopping 7.8mm stroke increase, with the two 62mm pistons now traveling a distance of 49.0mm inside the new aluminum open-deck cylinder bores that not only weigh 800 grams less, but also dissipate heat better than the old steel liners. Those pistons are 7.5mm shorter with revised hard-anodized crowns that lower the compression ratio from 11.6:1 to 10.6:1 (allowing the use of regular grade 87-octane fuel) while also weighing 3.4 grams less than the 250’s 121.6-gram slugs, reducing reciprocating loads enough to permit the retention of the 250’s 13,000 rpm rev limit. Also contributing here are 5mm-shorter piston pins that cut another 4 grams from the reciprocating weight.
The connecting rods are shorter by 2.8mm to maintain a mechanical advantage with the crankshaft’s longer stroke, with thicker ends for greater strength while still weighing the same as the previous rods. The crankcases have new oil passages, with a larger-volume oil pan (2.4L capacity instead of the 250R’s 1.7L) utilizing internal cooling fins to help dissipate heat; the pan not only has nearly half-inch better ground clearance than the previous unit, both the oil drain plug and new spin-on oil filter are accessible without removing any bodywork.
Up top, the U.S. version 250R’s antiquated 30mm carburetors have been finally replaced by a Keihin EFI setup using twin 32mm throttle bodies (which actually taper down from the 40mm secondary throttle plates for smooth throttle response). New injectors spraying a finer 60-micron droplet size feed into a cylinder head sporting reshaped intake ports that are 1mm wider at the port entrance and 0.5mm wider at the valve seat, which incidentally houses 1mm-larger 23.5mm intake valves.
The half-inch-wider rear rim...
The half-inch-wider rear rim allows the fitment of a 140-size rear tire, and the new IRC RX-01R tires provide surprisingly good grip and handling.
Spent gases are handled by a new single-muffler exhaust (versus the 250R’s dual muffler system) that utilizes tapered header pipes — expanding from 25.4mm at the exhaust port to 28mm just before the cross-over pipe — to improve midrange torque. The headers curve outward from each other to enable a longer center section (containing the single catalyzer versus the previous dual catalyzers, made possible by the EFI) for proper exhaust tuning. Toning the noise down is a trapezoidal cross-section muffler that offers adequate silencer volume without compromising ground clearance.
The transmission features an F.C.C. clutch (an OEM Japanese supplier that has been involved in Grand Prix racing) that has both slipper and power assist functions via different engagement cams. While the slipper clutch function helps with avoiding wheel lockup while downshifting, the unique power assist setup offers multiple benefits. Clutch pull effort is lighter due to the reduction in spring pressure needed (including using fewer springs), since the power assist cam actually forces the plates together under power; this also enables the clutch to handle more torque. The transmission gearsets have been beefed up, with the primary reduction gear widened from 10mm to 12mm thick, and the 6th gear gearwheels made from a stronger alloy.
That strengthening has been applied to the Ninja steel semi-backbone frame as well. High-tensile steel tubing said to be 150 percent stronger is used in its construction, with the layout of the main tubes wider with additional gusseting added in critical areas for increased rigidity. Because the frame is more rigid, it allowed Kawasaki engineers to isolate the engine in rubber mounts, significantly reducing the amount of vibration fed back into the chassis (and eventually back to the rider).
The boost in displacement...
The boost in displacement via a longer stroke is accompanied by a host of other revisions to help increase power across the rev range, resulting in performance that stomps the competition.
The Ninja 300’s frame has...
The Ninja 300’s frame has been beefed up significantly with tubing claimed to be 150 percent stronger and added gusseting in critical areas. The changes coupled with suspension alterations have resulted in a major upgrade in the Kawasaki’s handling.
The Ninja 300’s single two-piston...
The Ninja 300’s single two-piston caliper and 290mm disc (in both standard and ABS versions) provide excellent power and feel without being too aggressive for novice riders.
Suspension rates have been altered to work with the stiffer chassis. Interestingly, the non-adjustable fork’s compression and rebound damping have been softened, although the internal oil levels have been raised to provide progressive anti-bottoming resistance. Out back, the shock has had both compression and rebound damping stiffened up, along with a new longer (but same rate) spring that allows the preload to be both increased or reduced.
The rear wheel width has increased by 0.5 inches to accommodate a wider 140-size rear tire — bringing it on par with its Honda CBR250R competition — and in a continuing trend within the industry, an ABS version of the Ninja 300 will be available (in fact, all Kawasaki’s sportbikes will have an ABS version available in 2013). The ABS control unit is the latest generation Nissin system that is 60 percent smaller than current Nissin components, and is even smaller than the Bosch unit on the ZX-10R ABS; it weighs a paltry 631 grams (1.4 pounds).