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November’s EICMA show in Milan may reveal a new generation of supercharged Kawasaki engines and related models

Kawasaki shocked the world three years ago when it unveiled the supercharged H2 and H2R sportbikes. The 16-valve, DOHC, 998cc inline-four that powers both of those hot rods is boosted by a mechanically driven centrifugal supercharger to generate in track-only H2R trim 310 hp at 14,000 rpm and 115 pound-feet of peak torque at 12,500 rpm.

The engineering team had one obvious target: Give life to the most powerful production motorcycle in the history of the sport, whatever use that would be good for in real life. Large displacement, oversquare bore and stroke (76 x 55mm) for sky-high revs, plus supercharging—no prisoners taken.

While the H2/H2R is a clear statement of technological leadership, neither supercharging nor turbocharging has so far done for the motorcycle what it has done for 20 years for production automobiles: Allow a small engine to deliver high fuel economy at freeway speeds, yet with forced induction to also deliver spirited acceleration and real-world on-ramp performance.

The problem that has kept this from happening on two wheels is the limited tire footprint of the motorcycle. Not only does a motorcycle have only two wheels, but it uses only one-third of the width of those two tires. This small footprint cannot transmit the fast-rising and peaky torque of either turbocharging or the centrifugal supercharger of the Kawasaki H2/H2R.

A motorcycle’s drive wheel requires extremely smooth, predictable torque, which is why modern engine-control electronics (ride by wire, virtual powerband, traction control, anti-wheelie) have had such good success in smoothing the power delivery of existing bikes.

In revealing its “Balanced Supercharging” concept in 2015, Kawasaki showed a rotary shutter in the intake of a centrifugal blower (possibly similar to the “vortex throttle” used on Cosworth Champ Car engines) but did not explain either its purpose or function. We can only speculate that it might be used with fast computer control to maintain a desired boost pressure in an engine’s sealed intake airbox, thereby dealing with the old problem of torque that rises too fast for human control.

We will have to wait to see what Kawasaki reveals at EICMA this November. In a teaser about “Balanced Supercharging,” Kawasaki refers to a new generation of sport-tourers equipped with supercharged engines that were conceived to deliver supreme flexibility and great torque at relatively low rpm.

EXCLUSIVE VIDEO: Kawasaki Ninja H2R Dyno Run

Ford did something similar with its 1.0-liter three-cylinder EcoBoost engine, a little turbocharged monster that became the new standard in spark-ignited engineering for its solid peak power—140 hp at 6,000 rpm, combined with an incredibly thick and flat torque curve (133 pound-feet of torque at a mere 1,500 rpm)—and very low fuel consumption.

Ford applied lessons learned from diesel engine practice: a nearly flat pent-roof cylinder head (modest 22 degrees included valve angle) with the largest portion of the combustion chamber a deep bowl in the piston crown. This configuration proved effective at reducing knock despite compression exceeding 10:1, high for a mass-production supercharged engine.

In addition, the deep chamber keeps tumble turbulence alive through the compression/combustion cycle for perfect combustion and high efficiency. The combination proved to be a shortcut to high efficiency and torque not seen since the days of the Ford-Cosworth DFV 3.0-liter Formula 1 V-8, the engine that in 1967 set new thermodynamic standards.

Ford used turbocharging to reset the relationship between displacement, revs, and mean effective pressure, the main factors that participate in the definition of the power generated by internal-combustion piston engines. In this case, engineers drastically reduced the influence of revs and boosted mean effective pressure to an extremely high 304.5 psi. For a street-legal, naturally aspirated engine, we would be happy to see slightly more than half of that, say, 174 psi.

Not having to worry about mean piston speed, Ford engineers selected a small bore and a long stroke, which contributed to the clean, efficient, high-compression-ratio combustion chamber. Kawasaki appears to have adopted that same philosophy to deliver supremely flexible engines combining additional torque delivery, smoothness, and power.

Kawasaki used a mechanically driven supercharger for the H2/H2R. Can we in the future expect an electrically driven supercharger managed by the ECU for even higher engine efficiency and smoothness? Audi has done this with its SQ7 turbodiesel 4.0-liter V-8, and it works well.

If Kawasaki is able to combine small-engine economy with big-engine torque and power through a new and more controllable form of supercharging, that company will have opened a previously closed door to the future.


The Kawasaki KLX250 returns with key updates for 2018, shown here in new Digital Camo color option.

After a three-year hiatus, the KLX250 is back in the Kawasaki line-up and better than ever with the addition of fuel injection, new Uni-Trak suspension linkage and other changes to increase performance both on paved and dirt roads.

Borrowing notes from the KX line and Kawasaki’s racing heritage, this 2018 street legal, dual-purpose motorcycle is designed to cut through the busy traffic of an inner city or climb up a back trail to see the city from a beautiful view.

KLX250 Key Features

• New Fuel Injection System
• Revised Suspension Improves Handling
• Full Digital Instrumentation
• On/Off Road Capability
• One of Kawasaki’s Most Fuel-Efficient Motorcycles

The 2018 KLX250 motorcycle receives a new fuel injection system for improved starting at all elevations, fuel efficiency and performance. With riders of all skill levels in mind, Kawasaki’s target with the KLX250 are riders seeking a less expensive, lightweight dual sport motorcycle that is capable off-road.

The KLX250 features more aggressive styling noticeable in its front cowl, front fender, sharp taillight and two-bulb headlamp design. Taking cues from the KX family, the KLX250 motorcycle features two-piece radiator shrouds and KX-style fork guards, which help protect the inner tubes from rocks and brush.

An all-digital instrument console gives the rider at-a-glance information. Features include a digital bar-graph tachometer, digital speedometer, clock and dual trip meters. Fuel-injection and low-fuel warning lamps are also included.

Dual high-capacity Denso radiators, like those used on KX motocross bikes, deliver superior cooling efficiency and contribute to space and weight savings. The radiators are very slim and feature tightly packed cores and a fin design for improved heat dispersion.


• Liquid-Cooled, Compact 249cc 4-Stroke Engine
• New Fuel Injection (FI) system
• Improved throttle response and power
• Stainless-steel exhaust system

The engine of the KLX250 motorcycle is a modern, lightweight and compact, 249cc liquid-cooled DOHC engine with a wide torque band, pulling from down low. The new KLX250 features a new fuel injection system, for improved fuel efficiently, improved starting in a variety of conditions and better performance and throttle response. The FI system utilizes an ultra-fine atomizing (10-hole) injector. The result is a very smooth engine character, especially in the rpm range most used in day-to-day riding.

With an electric starter and Kawasaki Automatic Compression Release (KACR), which automatically lifts an exhaust valve during engine cranking, starting the KLX250 is a breeze. Precise control of ignition timing by the digital CDI also contributes to easy starts and reliability under extreme conditions.

The engine has low reciprocating weight, thanks in part to the use of a cam lobe for each valve, with shim-under tappet arrangement, which also contributes to better efficiency during high rpm. A lightweight piston, piston pin and connecting rod allow power-producing revs. With a bore and stroke of 72.0 x 61.2mm, the engine displaces 249cc. The engine is mounted low in the frame, contributing to a low center of gravity. Flat-top piston and pent-roof combustion chamber deliver a 11.0:1 compression ratio.

The engine of the KLX250 further features an electro-fusion cylinder, which is an ultra-hard coating that offers superior heat transfer and less weight. It also contributes to engine reliability: the coating holds lubrication well, resists abrasion and seizure, and allows a tight piston-to-cylinder clearance for increased horsepower.

Its smooth engine is due in part to a gear-driven engine balancer, providing smooth power delivery from idle to redline. On long rides this means greater rider comfort and less fatigue. The KLX250 motorcycle also features an all-stainless steel exhaust system, with a honeycomb catalyzer located in the muffler. Gear ratios facilitate smooth shifting through the rpm range and help with increased performance off-road and on. A revised shift drum offers an improved shift feeling, ensuring gears firmly engage.

Chassis & Suspension

• Fully adjustable suspension
• 43 mm inverted cartridge fork
• Gas-charged rear shock
• Front wheel travel of 255mm and rear travel of 230mm

The box- and tubular-section high-tensile steel perimeter frame of the KLX250 motorcycle creates a slim, lightweight package, which offers both great cornering performance and straight-line stability. The 26.5-degree caster angle and short wheelbase contribute to quick handling, while the high rigidity of the frame increases straight-line stability. The lightweight, highly rigid aluminum D-section swingarm also contributes to reduced unsprung weight and rigidity.

The 43mm inverted cartridge-style front fork comes with 16-way compression damping adjustment, adding incredible adjustability for a variety of riding conditions. The cartridge provides consistent damping force by minimizing aeration of the fork oil. Uni-Trak rear suspension provides great road holding ability and bump absorption. The gas-charged shock with remote reservoir has 16-way compression and rebound damping and fully adjustable preload adjustability.

Front wheel travel of 255mm and rear travel of 230mm creates a comfortable street ride and makes the KLX250 a capable off-road machine on the trails. Footpegs are positioned close to the bike’s centerline for a slim riding position conducive to both on- and off-road riding.

Wheels and Brakes

• 21-inch front and 18-inch rear wheels
• Front 250mm disc and 240mm rear disc

The KLX250 features a 21-inch front wheel and an 18-inch rear wheel, for great handling and plenty of tire options. Great wheel rigidity care of thick spokes (4.0mm), which contributes to lighter, smoother handling and offers greater durability for off-road riding.

Front and rear disc brakes offer great stopping performance, with a twin-piston caliper gripping a 250mm disc up front and a single-piston caliper gripping a 240mm disc in the rear.

Color: Lime Green
MSRP: $5,349
Availability: The 2018 Kawasaki KLX250 is available for purchase early October, 2017

KAWASAKI KLX250 Camo Edition 
Color: Matrix Camo Gray
MSRP: $5,549
Availability: The 2018 Kawasaki KLX250 Camo edition is available for purchase early October, 2017

KLX250 Specifications

Engine: 4-stroke, 1-cylinder, DOHC, 4-valves, liquid-cooled
Displacement: 249cc
Bore x Stroke: 72.0 x 61.2mm
Compression ratio: 11.0:1
Fuel System: DFI® with 34mm throttle body
Ignition: Electric CDI
Transmission: 6 speed, return shift
Final drive: sealed chain
Rake/Trail: 26.5°/4.1 in
Front Suspension/Travel: 43mm Telescopic fork/10.0 in
Rear Suspension/Travel: Uni-Trak® swingarm/9.1 in
Front Tire: 3.00-21 51P
Rear Tire: 4.60-18 63P
Front/Rear Brakes: Single disc
Frame Type: Tubular, semi-double cradle
Overall Length: 86.6 in
Overal Width: 32.3 in
Overall Height: 47.4 in
Ground Clearance: 11.2 in
Seat Height: 35 in
Curb Weight: 304.3 lb
Fuel Capacity: 2.0 gal
Wheelbase: 56.3 in
Trail: 110 mm (4.3 in)


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