Yep, it's that time of year...new bike intro time. How about a KX250F with fuel injection, and a new fork dubbed the SFF (Separate Function Fork)? Check out the details from Kawasaki below, and for more photos, click into either of the photo gallleries above.

2011 Kawasaki KX™250F

More AMA Lites Championships than any Motorcycle in History!

It’s an old refrain: The factory guys get all the good stuff. Their bikes are faster, lighter and just plain tricker than the motocrossers you can buy off the showroom floor. There’s some truth there. But that’s changing. The gap between production and factory-prepped motocrossers has never been narrower. And with the introduction of Kawasaki’s massively reworked 2011 KX™250F, that gap just shrank a little more.

All told, there are nearly 30 upgrades to the new KX250F, all of which reflect the stunning level of testing and development happening behind the scenes at Kawasaki’s R&D and race teams. And Kawasaki does this for one reason: To put you on the fiercest, most capable motocrosser in the industry.

When reworking the new KX250F, engineers started with what’s arguably already the gold standard in 250-class racing – the 2010 KX250F. Just ask Christophe Pourcel and Jake Weimer, who won the 2010 AMA East and West Lites titles, respectively, on their Monster Energy™/ Pro Circuit / Kawasaki-backed KXs. Or read the long list of enthusiast magazine shootouts that picked the 2010 KX250F as the best motocrosser in its class.

For 2011, the goal was an even faster and more ridable KX250F. On the more powerful side of the equation are loads of engine modifications, all of which have made the latest KX an absolute corner-to-corner screamer. The big news is the addition of Digital Fuel Injection (DFI®) that not only helps produce stunning – and more useable – power, but also makes tuning a much easier proposition. The system, basically identical to the one fitted to the 2011 KX450F, automatically adjusts to suit track and climate conditions, and offers consistent fuel metering and response even when the going gets rough, such as when landing off jumps or slamming through the whoops. The simple and highly efficient DFI system incorporates a compact and lightweight Electronic Control Unit (ECU), a 43mm throttle body, a lightweight aluminum fuel pump and an ultra-fine atomizing injector. Set at a 45-degree angle for optimum mid-range power, the injector shoots precisely metered fuel directly into the intake tract for smooth power delivery and highly accurate engine response throughout the entire rpm range. The 250F’s injector actually flows more fuel than the 450F’s unit due to the 250F engine’s higher speeds, while airflow through the system is actually higher than through the 2010 model’s carburetor setup.

Designed specifically for motocross, the KX250F’s lightweight DFI system requires no battery; the engine can be started within three rotations of the crankshaft using only the electricity generated through the initial stroke of the kickstarter. What’s more, an optional ECU Setting Tool allows racers to select from several different ECU data maps, or fine tune a custom map that alters fuel injection and ignition timing to suit different tracks and conditions. The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, coolant and air temperatures, ignition timing, fuel adjustments, gear position and system voltage.

You’ll find more significant changes farther downstream, such as higher compression – now 13.5:1 vs. 13.2:1 – via a modified cylinder and changes to the top of the exclusive Bridged-Box Bottom piston. The intake camshaft now produces higher valve lift, while the intake valve spring is stronger to handle the extra load. The crankshaft’s rotational inertia has been slightly modified to better match the new engine’s characteristics, while a slightly longer spark plug design – and a new coil offering a hotter and longer-duration spark – improves combustion performance. Transmission and final-drive ratios have been altered slightly to match the engine’s newfound response, and a modified shifting mechanism allows you to access those speeds more easily and smoothly. There’s 10% more air-cleaner duct volume for better breathing, and on the exhaust side, a longer head pipe gives the engine a touch more low-end power, while a higher-volume muffler assembly lowers noise to comply with the 94 db AMA Pro Racing limit, while retaining optimum power production up top.

The chassis has been massaged every bit as thoroughly as the engine, with Kawasaki’s new Separate Function Fork (SFF) leading the list of changes. Unlike a conventional fork design, where each fork leg handles both springing and damping, the SFF separates spring and damping functions for improved performance, 25 percent less stiction, lower weight and easier adjustability. The right leg accommodates the spring side of the equation, incorporating a larger main spring/rod assembly than traditional forks, plus a small amount of oil for lubrication. Spring preload is now adjustable via a blue-anodized adjuster on the right leg’s cap. The left leg handles damping duty, with only its cartridge damper assembly and fork oil inside the tube. Rebound and compression damping are adjustable on the fork tube. In addition to the natural reduction in stiction provided by the SFF design, the KX250F’s fork sliders are titanium oxide coated. Lower stiction and better overall fork action are keys to the new fork’s performance, and they are traits you’ll appreciate the first time you charge into a bump-infested corner at speed. Fork offset has also been reduced by a full millimeter for lighter handling and quicker steering response.

Out back, the rear shock incorporates revised damping settings that more closely match the SFF’s performance. The result is even more wheel and chassis control while ripping across a set of whoops or shrieking through that fast, rutted corner leading onto the front straight. Like the KX450F, the new 250F gets a reworked seat with grippier material along the sides for improved rider grip while standing when the action gets hot and heavy.

The rest of the package includes the same top-tier components that have put the KX250F atop the podium for years. The KX250F’s aluminum perimeter frame, with its lightweight blend of forged, extruded and cast parts, has the chassis balance, rigidity and durability experienced riders want and need, and locates the engine, rider and pivot points where they perform best.

Designed with rider ergonomics foremost in mind, the KX250F’s bodywork offers riders a slim interface and a natural positioning that make going fast a simple affair. The sleek bodywork components include one-piece plastic shrouds and side number plates. The upgraded seat provides excellent seated grip and rider mobility, and features firm urethane foam to hold its shape longer. Chassis protection bits include the large, resin skid plate, rear caliper guard and a redesigned chain guide with approximately 2.5 times more durability than the 2010 unit.

The KX’s 249cc, liquid-cooled, four-stroke engine is a veritable powerhouse, and features an electrofusion cylinder treatment on the cylinder bore, a crankshaft balance factor of nearly 60 percent (on par with Pourcel and Weimer’s factory racebikes), for reduced vibration and smoother power delivery, a highly durable – yet slick-shifting – transmission, stronger-than-ever crankcases and a level of reliability that’ll keep you out there and on-track all season long. It’s been rated the best engine in its class by various magazine editors, and you’ll understand their thinking after your very first ride.

The rest of the KX250F package is every bit as impressive as the engine and chassis. Aside from the sort of fit and finish you expect from Kawasaki, there’s also a premium-quality Renthal aluminum handlebar included standard, black alumite-coated aluminum wheels that are both light and strong, a ribless rear hub and butted spokes that further reduce unsprung weight, and factory-style graphics that finish things off nicely and highlight the KX250F’s amazing on-track abilities.

Racers who ride their KX250F at designated events are eligible to receive support from Team Green, Kawasaki’s amateur racing support program. Each year, Team Green™ provides regional support vehicles and highly trained technicians at more than 100 events throughout the United States, offering technical information and assistance to those who race Kawasaki products. Kawasaki also offers a comprehensive contingency program for amateur and professional riders who place well at designated events.

Authentic Kawasaki Accessories are available through Kawasaki dealers.

Kawasaki Motors Corp., U.S.A. (KMC) markets and distributes Kawasaki motorcycles, ATVs, personal watercraft, utility vehicles and recreation utility vehicles through a network of more than 1,475 independent retailers, with an additional 8,000 retailers specializing in Kawasaki power products and general purpose engines. KMC and its affiliates employ nearly 3,300 people in the United States, with 400 of them located at KMC's Irvine, California headquarters.

Kawasaki’s tagline, “Let the good times roll.™”, is recognized worldwide. The Kawasaki brand has become synonymous with powerful, stylish motorcycles for over four decades. Information about Kawasaki’s complete line of recreational products and Kawasaki affiliates can be found on the Internet at www.kawasaki.com.

Features and Benefits

At a Glance…

− New Digital Fuel Injection (DFI) system
− New Showa Separate Function Fork (SFF) divides spring and damping functions; springing in the right leg and damping in left provide less stiction, better performance and easier adjustability
− Increased engine performance via higher compression and exhaust/intake changes
− High-performance piston featuring bridged-box bottom design
− Stainless steel exhaust features longer header section and larger-volume muffler
− Revised suspension settings front and rear aimed at race-experienced riders

High-Revving, High Performance Engine
− 249cc, liquid-cooled, four-stroke, four-valve, single-cylinder DOHC engine delivers hard-hitting power across the rpm range
− Modified intake valve timing and cam profile for increased valve lift improves high-rpm power production
− Intake valve spring tension increased to control more radical cam timing
− Digital Fuel Injection (DFI) system allows consistent fuel delivery, quick starts and easy adjustability
− Engine tuned to achieve the widest possible torque band to maximize traction through a greater percentage of the rev range
− Race-experienced riders able to harness high-rpm performance that extends way into the over-rev
− Sprocket-style chain drive roller helps reduce the effect of driveline lash and engine braking for smoother and faster corner entries
− Crank web design features a balance factor on par with the factory racers for reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range

Digital Fuel Injection (DFI) System
− Same basic system that’s fitted to the KX450F
− 43mm throttle body assembly with 20 percent higher-flow injector than the KX450F’s injector
− Intake airflow is higher than on carburetor-equipped 2010 model
− Progressive throttle link; opens more quickly after 3/8 open position
− Simple and efficient system: No battery, fuses or relays
− Improves engine response across entire rpm range
− Offers easy engine starting
− Prevents engine hesitation after landing from jumps and other high-impact situations
− Optional Calibration Kit allows easy tunability
− Optional FI Indicator Light allows the DFI system to communicate diagnostic information

Bridged Box-Bottom Piston
− Light and strong piston shares same design as the factory racers, with a revised crown for higher compression. Also features fully flush internal bracing
− Short piston pin reduces reciprocating weight

Lightweight and Efficient Top End
− Lightweight, highly rigid, titanium 31mm intake and 25mm exhaust valves reduce reciprocating weight and offer high-rpm reliability
− Ultra-light valves have extremely thin valve stems on par with those found in supersport machines; intake valves feature thick heads for increased strength
− Intake ports designed for peak performance at all rpm, especially in the high-rpm range
− Special coating applied to intake port cores during casting gives the intake ports extremely smooth surfaces and optimum intake efficiency across the rev range
− Silicon-coated head gasket provides excellent sealing

Enhanced Durability and Reliability
− Electrofusion treatment on cylinder bore improves surface oil retention, while the molybdenum coating on the cylinder bore surface helps resist scorching, further contributing to durability
− Wide big-end bearing features a thick copper plate on its cage and a long crank pin for increased reliability
− Oil pump rotors offer a high degree of reliability and durability; a large feed pump rotor maximizes oil flow, while a smaller scavenge-pump rotor reduces mechanical losses

New Stainless Steel Exhaust System
− Stainless steel construction offers extra durability
− Longer header pipe section for improved low and mid-range response
− Higher-volume muffler assembly quiets emissions to 94 dB noise regulations while retaining power production
− Joint between pipe and muffler offers excellent sealing, while a rubber damper collar on the rear silencer mount equals serious durability

Efficient Cooling System
− Thick and wide radiators are strong and offer excellent resistance to mud buildup while providing superb cooling performance
− Cylinder head water jacket routes coolant to the front of the cylinder head for even cooling

Transmission and Shifting Reliability
− Third and fourth input gears have large dogs to help prevent wear
− Revised ratchet and lever angle for more positive shifting
− Revised internal ratios for second and fourth gear better match new engine power delivery
− New 50-tooth rear sprocket helps capitalize on the engine’s torque delivery
− Strong, beefy crankcases feature additional material around the engine mounts to help increase long-term durability
− Clutch cable holder is integrated with the crankcase for accurate feel at the clutch lever
− Scavenge oil filter screen can be accessed without splitting the crankcases, facilitating easier maintenance

Quick-turning Chassis
− Utilizes a low-rigidity steering stem for lighter handling
− The KX250F’s slim and lightweight aluminum perimeter frame is composed of forged, extruded and cast parts
− Center of gravity and key dimensions such as swingarm pivot, output sprocket and rear axle locations designed to increase forward drive with minimal rear-end squat
− Upper engine mounts on head cover sides increase overall rigidity

Race-oriented Suspension
− Revised race-oriented suspension damping settings optimize front/rear balance
− New Separate Function Fork (SFF) separates springing and damping functions for less weight, better performance, less stiction and easier adjustability
− Fork now allows external spring preload adjustability
− Super-hard titanium coating on the outer surface of the inner fork tubes reduces stiction and improves suspension action. The increased surface hardness also helps prevent scratches and tube damage
− Friction-reducing Kashima Coat treatment on the inside of the outer fork tubes contributes to smoother suspension action
− Wrap-around fork tube guards provide greater protection for the inner tubes
− Revised shock damping settings offer increased absorption performance and greater stability on corner entry thanks to reduced rear-end kicking
− Features Kashima Coat on the inside of the shock reservoir for reduced friction and smoother suspension action
− Rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately

Superior Rear-wheel Traction
− Swingarm features optimum internal bracing and flex characteristics for improved cornering performance
− Alloy swingarm uses a cast front section, tapered hydroformed spars and forged chain adjusters
− Uni-Trak® rear suspension system mounts the suspension arm below the swingarm, allowing more rear suspension stroke and precise tuning
− Linkage ratios for the Uni-Trak rear suspension match rear shock damping settings to achieve maximum rear wheel traction

Rider Interface
− Bodywork components offer the rider a slim interface, making it easy for racers to feel comfortable and go fast
− Formed using a double-injection molding process, the two-tone shrouds offer a slim design
− Side number plates also two-toned and contribute to the slim package
− Right side panel has an added passageway to help cool the silencer
− Frame is wider at the ankles to offer better grip and narrows near the bend below the seat to allow a slim riding position
− Slim seat features firm urethane, which keeps its original shape longer
− Seat has a slip-resistant top and side surface for good grip when seated and while standing
− 50mm wide (front-to-rear) footpegs offer superb grip and feel at the pegs
− Clutch cable boot features a large quick adjuster, making it easy for riders to adjust play in the clutch cable while on the fly
− Throttle grip has a one-piece collar that provides additional stability during throttle operation
− Lightweight short-length grips feature a pattern designed to provide excellent grip

Factory-style Components
− Black alumite-coated rims, just like the factory racers
− Lightweight rims offer maximum strength and weight savings
− Thick and rigid front fender
− Rear brake pad material offers powerful braking performance
− Front and rear petal brake discs help reduce unsprung weight, and the wave shape helps clean the brake pads for more efficient braking performance
− Rear caliper guard protects caliper from damage
− Ribless rear hub and butted spokes further reduce unsprung weight
− Renthal aluminum handlebar is standard equipment
− Factory-style graphics complement the KX250F’s highly tuned performance

Additional Features
− Large front brake lever boot offers increased protection against debris
− Newly designed and more durable chain guide utilizes a thicker wear pad for longer life
− Large resin skid plate offers great protection with minimum weight

Optional Accessories
− Optional DFI Calibration Kit allows custom tuning
− Optional FI Indicator Light allows the DFI system to communicate diagnostic information
− Engine parts include magneto rotors with different inertias and a 12-tooth output sprocket
− Optional chassis parts include handlebar holder for a 1 1/8-inch handlebar, 46- to 50-tooth aluminum and steel rear sprockets, solid petal brake rotors, different fork and shock springs and manual decompression lever and cable

Specifications*
Engine: Four-stroke single with DOHC and four valves
Displacement: 249cc
Bore x stroke: 77.0 x 53.6mm
Cooling: Liquid
Fuel injection: 43mm Keihin throttle body
Compression ratio: 13.5:1
Ignition: Digital CDI
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame: Aluminum perimeter
Rake / trail: 28.2 degrees / 4.7 in.
Front suspension / wheel travel: 47mm inverted Showa SFF telescopic fork with spring preload adjustability and 22 position compression and 20 position rebound damping adjustability/ 12.4 in.
Rear suspension / wheel travel: Uni-Trak® linkage system and Showa shock with 19 position low-speed and stepless high-speed compression damping, 22 position rebound damping and fully adjustable spring preload / 12.2 in.
Front tire: 80/100-21
Rear tire: 100/90-19
Front brake: Single semi-floating 250mm petal disc with dual piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 85.4 in.
Overall width: 32.3 in.
Overall height: 50.0 in.
Wheelbase: 58.1 in.
Ground clearance: 13.0 in.
Seat height: 37.2 in.
Curb weight: 232.7 lbs.
Fuel capacity: 1.9 gal.
Color: Lime Green
MSRP: $TBD
Wholesale distributor: Kawasaki Motors Corp., U.S.A.
9950 Jeronimo Road
Irvine, California 92618
(949) 770-0400
www.kawasaki.com

2011 Kawasaki KX™450F

Did Somebody Say Motor?

In the 450cc motocross game, the only thing that matters to serious racers is top-tier performance and running up front. And for 2011, the best tool for the job is once again a lime green one – Kawasaki’s reworked and revised KX™450F. In this arena you can’t stand still technically, which is why Kawasaki engineers scrutinized every system and component of the race-winning 2010 model and came up with a host of tweaks that’ll have red, blue, orange and yellow wondering what hit ’em.

The latest open-class KX starts with the primary pieces that allowed the 2010 KX to win more Supercross events than any other bike last year – a brutally fast 449cc DOHC four-stroke single packing a broad spread of power housed in a lightweight-yet-strong aluminum frame connected to a suspension designed to offer compliance, high-speed stability and whoop-sucking performance all moto long. It was an ideal platform on which to win the majority of races in 2010, and that trend promises to continue with the revised, even faster 2011 model.

Last year, the KX450F featured a number of engine refinements, including the first ever production use of a bridged-box-bottom piston (more high-end power and better over-rev characteristics), revised cam timing for better mid- and top-end performance and a reinforced cylinder sleeve and crankcase for improved durability.

This year there’s even more. Piston shape, for instance, has been modified to meld with the upgraded, higher-volume muffler, which is quieter than last year’s unit. The ECU has been tweaked to provide a hotter and longer-duration spark for improved low-rpm response. The shift mechanism incorporates a larger internal roller and stronger shift-spring tension for more positive shifting. Finally, the fuel-injection system’s Calibration Kit software has been updated, while the controller harness and connector have been modified for easier use.

Changes in the chassis department are equally impressive, and show the results of our race team’s effect on development. First up are revisions to the engine mount brackets that optimize chassis flex and improve handling. Next, the engineers revised the damping settings for the massive fork tubes for even better performance. For that factory-bike touch there are also blue-anodized compression damping adjuster caps in place of last year’s silver ones. Damping settings on the rear shock have also been revised, and it, too, gets a blue-anodized compression adjuster. The seat features a new side-surface texturing for increased rider grip while aboard, and the drive chain guide has been thoroughly beefed up for increased durability; testing shows it to be nearly three times more durable than the unit fitted to the 2010 machine.

The race-ready engine is compact and light, with a short 100mm cylinder head and a 12.5:1 compression ratio. A wedge-shaped crank web offsets 60 percent of the crankshaft’s reciprocating weight, producing an effective “counterweight” effect. This is on par with Kawasaki’s factory racers and helps reduce engine vibration, smooths power delivery and enhances low-rpm throttle response. A stainless steel exhaust pipe connects to the revised silencer, which uses long-fiber packing material to maximize service intervals. A rubber damping collar in the rear silencer mount provides a boost to long-term durability. The KX450F’s Digital Fuel Injection (DFI®) automatically adjusts to suit track and climate conditions, and offers stable fuel metering even when landing from jumps in tough motocross conditions. The DFI system includes a compact and lightweight ECU, a 43mm throttle body, a lightweight aluminum fuel pump and an ultra-fine atomizing injector. Set at a 45-degree angle for ideal mid-range power, the 12-hole injector sprays precise, 60-micron fuel particles for smooth power delivery and accurate engine response throughout the rpm range.

Designed specifically for motocross, the KX450F’s lightweight DFI system doesn’t require a battery; the engine can be started within three rotations of the crankshaft using only the electricity generated through the initial stroke of the kickstarter.

An optional ECU Setting Tool allows racers to select from several different ECU data maps, or fine tune a custom map that alters fuel injection and ignition timing to suit different tracks and conditions. The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant and air temperatures, ignition timing, fuel adjustments, gear position and system voltage.

The engine’s phenomenal power is delivered through a clutch that features an ultra-light operating plate with superb oil drainage and beefy friction plates. The entire assembly is designed to provide exceptional clutch feel and durability. The drive chain features thin inner links and a slight weight savings relative to typical designs to help boost acceleration. The revised suspension damping settings provide lighter handling, improved suspension action, increased comfort and greater cushioning when landing from jumps.

The 2011 KX450F’s D-shaped aluminum swingarm features a cross section with narrow ribs and thin walls. It pivots high in the aluminum frame to maximize rear wheel traction. Mounting the arm of the Uni-Trak® rear suspension linkage below the swingarm provides a long rear suspension stroke and facilitates precise shock tuning.

Complementing the responsive chassis is a Kayaba Air-Oil-Separate (AOS) fork that offers precise cornering and sharp handling. The fork features a Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes to minimize stiction when the fork is exposed to lateral forces that would otherwise restrict slide action. The result is smooth and precise response, especially during cornering. Overall suspension action is extremely smooth due to a friction-reducing Kashima Coat treatment on the inside surfaces of the outer fork tubes and the rear shock reservoir. Wrap-around fork guards provide excellent protection for the sliders.

The 2011 KX450F’s Kayaba rear shock’s revised damping settings contribute to improved wheel control and impact performance when landing from jumps. It features a large 50mm piston and a Kashima Coat treatment on the shock internals to help maintain a plush feel throughout the toughest motos. Easily accessible dual compression adjusters allow high- and low-speed damping to be tuned separately, giving mechanics and riders the ability to easily fine tune the suspension for difficult track conditions.

A slim seat design with firm urethane foam and a non-slip top and side surface provides even more seated and standing grip while retaining excellent rider mobility. The frame echoes the slim profile at the top, but widens at the lower end by the ankles to provide the rider with better feel and control. Completing the rider interface are wide 50mm footpegs that offer tenacious grip and a comfortable platform.

The 2011 KX450F is available in Kawasaki Lime Green, with black alumite-coated rims and aggressive graphics for a factory appearance.

Racers who ride their KX450F at designated events are eligible to receive support from Team Green™, Kawasaki’s amateur racing support program. Each year, Team Green provides regional support vehicles and highly trained technicians at more than 100 events throughout the United States, offering technical information and assistance to those who race Kawasaki products. Kawasaki also offers a comprehensive contingency program for amateur and professional riders who place well at designated events.

Kawasaki Motors Corp., U.S.A. (KMC) markets and distributes Kawasaki motorcycles, ATVs, personal watercraft, utility vehicles and recreation utility vehicles through a network of more than 1,475 independent retailers, with an additional 8,000 retailers specializing in Kawasaki power products and general purpose engines. KMC and its affiliates employ nearly 3,300 people in the United States, with 400 of them located at KMC's Irvine, California headquarters.

Kawasaki’s tagline, “Let the good times roll.™”, is recognized worldwide. The Kawasaki brand has become synonymous with powerful, stylish motorcycles for over four decades. Information about Kawasaki’s complete line of recreational products and Kawasaki affiliates can be found on the Internet at www.kawasaki.com.

Features and Benefits

At a glance…
− Massively powerful engine
− Revised suspension settings
− Improved shifting performance
− Revised seat
− Refined ECU settings
− Easier fuel injection calibration system access
− Still easy to start!

Engine Overview
− 449cc liquid-cooled, DOHC, four-stroke single
− Bridged-Box Bottom piston design offers optimal engine performance
− Reinforced crankcase is strong and durable
− A forward lean angle of 3 degrees puts the engine in the ideal position for maximum traction
− Tuned for a broad powerband with the torque curve set just under the wheelspin threshold
− High-acceleration cams help the engine rev quickly
− Maintenance-free automatic cam chain adjuster
− Large airbox flap helps prevent mud and water from entering

Bridged-Box Bottom Piston
− Same design as used on our factory racers; offers improved performance at all rpm
− Lighter and more durable than traditional piston designs
− Short piston skirt features low-friction coating for reduced mechanical losses
− Reinforced external ribs for strength and durability
− Revised profile with fully flush internal bracing results in a lighter, stronger piston
− Short piston pin offers increased strength

Cylinder Head
− Compact head is only 100mm tall
− 36mm titanium intake and 31mm exhaust valves with aluminum spring retainers minimize reciprocating weight and cylinder height to help ensure reliable valve control at high rpm
− Double valve springs allow a short cylinder head height and help ensure stable valve operation
− Camshafts, lobes and tappet surfaces feature a soft-nitride treatment for long wear and high-rpm reliability

Crankshaft
− Crankshaft with high inertial mass helps maximize rear wheel traction
− Wedge-shaped crank web provides enough offsetting moment for a 60 percent balance factor – and is similar to the crank balance in Kawasaki’s factory race engines, resulting in reduced engine vibration, smoother power delivery and increased performance, with a noticeably snappier response at low rpm
− Crankshaft and connecting rod feature a special carburizing and quenching treatment to maximize rigidity

Digital Fuel Injection
− Self-adjusts to atmospheric changes for easier starting, sharper throttle response and optimized power and stability when jumping/landing
− It is not necessary to re-tune, or change any jets to suit climatic conditions like on a carbureted model
− Ultra-fine atomizing injector with 10 holes sprays particles with a droplet size of 60 microns for smooth power delivery and engine response throughout the throttle range
− 43mm throttle body uses a progressive throttle linkage to deliver airflow in much the same way as an FCR carburetor
− Using two linked shafts, the throttle body opens more quickly after reaching the 3/8 open position
− Lightweight throttle body is approximately half the weight of a FCR carburetor, saving over one pound in weight
− Fast-idle knob on the throttle body allows riders to increase engine speed when starting a cold engine
− Fuel injector set at 45 degrees, the optimum angle for mid-range power

High-performance ECU
− New ECU programming and revised settings offer improved response at low-mid rpm
− No battery needed; the engine can be started with only three rotations of the crankshaft using the electricity generated by a single kick of the starter
− The system delivers electricity to FI system in sequence: first the ECU, then the fuel pump, and finally the injector for quick, easy starting
− Starting can be accomplished in a single kick
− The compact, lightweight ECU, located on the front of the steering head behind the number plate, was designed specifically for motocross use. The fuel pump relay is integrated with the ECU to help cope with the shocks and vibrations of motocross riding

Optional User ECU Setting Tool
− Allows racers to reprogram the ECU’s data maps for volume of fuel injected and ignition timing to alter engine characteristics to suit rider preferences
− The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant temp, air temp, ignition timing, fuel adjustments, gear position and system voltage

Easy Starting
− Strong output from the large ACG rotor provides enough electrical power for the battery-less FI system to enable true one-kick starting without using a battery
− Equipped with an automatic compression release (ACR) system for quick and easy starting. The dual-weight centrifugal decompression system is fitted to the exhaust cam
− Compression release features 1.0mm of valve lift, to minimize the required kicking power

Lightweight Aluminum Fuel Pump
− Located in the fuel tank but at a new angle to help prevent damage in extremely rough riding conditions
− Features a rubber fuel filter cover that wraps around the inlet port and acts as a fuel trap to help ensure a stable fuel supply during vigorous motocross riding
− 1.9-gallon fuel tank is formed using a rotational molding process

Efficient Cooling
− High-capacity Denso radiators feature tightly packed cores and a fin design that delivers superior cooling efficiency
− Radiators don’t need reinforcing brackets, which results in lower overall weight
− Shrouds feature a slim design that melds with the radiators’ design
− Radiator louvers feature four small blades set at a shallow angle for minimum overlap and maximum air flow

Strong and Durable Clutch
− Clutch assembly provides a direct feel and superb control
− Excellent oil drainage contributes to more direct feel
− Friction plates with substantial friction material contribute to a more direct feel
− Large operating plate pusher reduces the clearance between the pusher and the input shaft hole, improving clutch operation

Close-Ratio 5-Speed Transmission
− 5-speed transmission and low-rpm engine response combination offers riders more gear options for traversing rough sections or getting into the rhythm of a course easily so they can focus more on racing
− Thinner inner-link chain is light and strong
− Sprocket-style chain drive roller reduces the effect of driveline lash, helping smooth engine braking and facilitating additional corner entry control

Exhaust
− Short, one-piece stainless steel exhaust pipe contributes to optimum mid-high rpm performance
− Optimized exhaust routing contributes to improved ergonomics
− High-volume silencer helps meet noise regulations – currently 94 dB
− Right side panel has special passageway to help cool the silencer

Powerful Disc Brakes
− Rear brake pad material offers strong braking performance
− Powerful twin-piston hydraulic front caliper
− Lightweight semi-floating 250mm petal-type front brake rotor
− Single piston hydraulic rear caliper squeezes lightweight 240mm petal-type rotor

Light, Slim Chassis
− Revised engine mount brackets optimize frame rigidity for better handling
− Lightweight steering stem shaft contributes to light, nimble handling
− Main frame spars are 68mm tall and 24mm wide to provide an ideal balance between stiffness and compliance
− Weight-saving features include a slim head pipe, narrow cross-section and a downtube formed with a swaging (squeezing and hammering) process
− Swingarm pivot is located high in the frame to maximize rear wheel traction

Aluminum Swingarm
− Cross-section design contributes to light handling
− Tapered “D” shape swingarm provides ideal rigidity for excellent stability, and is lighter than a comparable box-section unit
− Alloy swingarm features a cast front section, tapered hydroformed spars and forged chain adjusters
− Uni-Trak® rear suspension linkage ratio maximizes rear traction performance
− Suspension arm is mounted below the swingarm to allow a longer rear suspension stroke and more precise tuning

Front Fork
− Race-oriented suspension settings offer maximum overall performance
− Revised damping settings offer improved action and increased comfort during the initial phase of the suspension stroke
− Kayaba Air-Oil-Separate (AOS) fork keeps oil and air in separate chambers for stable damping performance during long motos. Low-friction fork seals contribute to smooth action
− Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes offers minimum stiction when the fork is exposed to lateral forces that would usually hamper slide action. The result is improved fork response, especially during cornering
− Friction-reducing Kashima Coat on the inside of the fork’s outer tubes contributes to smooth suspension action (especially at the initial part of the stroke) and a superb ride feel
− Wrap-around fork tube guards offer effective protection for the sliders

Rear Shock
− New damping settings contribute to increased stability and improved impact performance when landing from jumps
− Rear suspension settings and linkage ratios derived from extensive rider testing
− Kayaba rear shock features a large 50mm piston
− Rear shock features dual compression adjustability, allowing high-speed and low-speed damping to be tuned separately
− Also features Kashima Coat treatment on the cylinder for reduced friction and smoother suspension action
− Easy adjuster access for track-side suspension tuning

Rider Interface and Styling
− Dual injected two-tone, one-piece plastic shrouds and side number plates
− Optimized exhaust routing contributes to improved ergonomics
− Right side panel has special passageway to help cool the silencer
− Black plastic covers, triple clamps, engine covers, and black alumite-coated rims – just like Kawasaki’s factory teams
− Wide 50mm footpegs provide excellent feel and a comfortable platform
− Frame is wider at the ankles to offer optimum grip, narrows below the seat to allow a slim riding position
− Slim seat design uses firmer urethane foam that keeps its original shape longer for the best possible ergonomics and feel
− Seat has a slip-resistant top surface for good grip when seated and a new material along the sides for extra grip when standing

Additional Features
− Skid plate made of resin material offers great protection without excess weight
− Clutch cable boot features a large quick adjuster, making it easy for riders to adjust play in the clutch cable on the fly
− Increased front axle collar diameter transmits more feedback from the contact patch to the rider
− Ribless rear hub and butted spokes offer light weight and excellent durability
− Rear caliper guard helps protect the caliper from damage

2011 Kawasaki KX™450F Specifications*

Engine: Liquid-cooled, four-stroke single with DOHC and four-valve cylinder head
Displacement: 449cc
Bore x stroke: 96.0 x 62.1mm
Compression ratio: 12.5:1
Fuel Injection: 43mm Keihin throttle body
Ignition: Digital DC-CDI
Transmission: Five-speed
Rake / trail: 26.7 degrees / 4.6 in.
Front suspension / wheel travel: 48mm inverted, Kayaba AOS with DLC coated sliders, 22-position compression and 20-position rebound dampening adjustment / 12.4 in.
Rear suspension / wheel travel: Uni-Trak® linkage system and Kayaba shock with 50mm piston, 22-position low-speed and stepless high-speed compression dampening, 33-position rebound dampening and fully adjustable spring preload / 12.4 in.
Front tire: 90/100-21
Rear tire: 120/80-19
Front brake: Single semi-floating 250mm petal disc with dual piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 86.0 in.
Overall width: 32.3 in.
Overall height: 50.4 in.
Wheelbase: 58.3 in.
Ground clearance: 13.2 in.
Seat height: 37.8 in.
Curb weight: TBD lbs.
Fuel capacity: 1.9 gal.
Color: Lime Green
MSRP: $TBD
Wholesale distributor: Kawasaki Motors Corp., U.S.A.
9950 Jeronimo Road
Irvine, California 92618
(949) 770-0400
www.kawasaki.com



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5 comments
  • mx317

    5/30/2010 5:29 PM

    Marzocchi forks on motorcycles were like this many years ago.

  • IMoto122

    5/25/2010 7:04 PM

    Wouldn't you think that fork design would require a mega-strong axle and clamps? My forks on my 50 have the same design and you can actually feel which leg has the spring..(I'm sure kawi figured that out) I can't wait to get a chance at that 250f!

  • GuyB

    5/25/2010 3:29 PM

    Yep, it used to be that technology flowed from moto to mountain bikes, rather than the other way around.

  • englishman

    5/25/2010 3:22 PM

    Mountain bikes have had seperate compression / rebound legs for a few years now.

  • Lightning78

    5/25/2010 2:27 PM

    Wow those 250f forks are insane!!!!!!!

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