2012 Kawasaki, 2011 Kawasaki, and 2010 Kawasaki Dirt Bikes.

In the 450cc motocross game, the only thing that matters to serious motocross 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 KX450F. In this arena you can’t stand still technically, which is why the engineers for Kawasaki dirt bikes scrutinized every system and component of the race-winning 2010 Kawasaki KX450F 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 Kawasaki Dirt Bikes start with the primary pieces that allowed the 2010 Kawasaki KX 450 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 Kawasaki KFX 450 model.

The 2010 Kawasaki KFX 450 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.

However, the 2011 Kawasaki KFX 450 has even more. The bridged-box bottom 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 Kawasaki dirt bikes 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 responsible for Kawasaki dirt bikes 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 Kawasaki KFX 450 machine.

The Kawasaki dirt bikes 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 10-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 Kawasaki KFX 450 ’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 moto 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 Kawasaki dirt bikes suspension damping settings provide lighter handling, improved suspension action, increased comfort and greater cushioning when landing from jumps.

The 2011 Kawasaki KFX 450 ’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 Kawasaki KFX 450 ’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 Kawasaki dirt bikes 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 Kawasaki KFX 450 is available in Kawasaki Lime Green, with black alumite-coated rims and aggressive graphics for a factory appearance.

Motocross racers who ride Kawasaki Dirt Bikes 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.

2011 Kawasaki KX250F Dirt Bikes:

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 dirt bikes massively reworked 2011 KXF 250, that gap just shrank a little more.

All told, there are nearly 30 upgrades to the 2011 KXF 250, all of which reflect the stunning level of testing and development happening with engineers responsible for Kawasaki dirt bikes and Kawasaki USA race teams. And Kawasaki does this for one reason: To put you on the fiercest, most capable motocrosser in the industry.

When reworking the 2011 KXF 250, engineers started with what’s arguably already the gold standard in 250-class racing – the 2010 KXF 250. 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 the long list of enthusiast magazine shootouts that picked the 2010 KXF 250 as the best motocrosser in its class.

For 2011, the goal was an even faster and more rideable KXF 250 Kawasaki dirt bikes. 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 Kawasaki KFX 450, 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 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 dirt bikes 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 friction, 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 friction provided by the SFF design, the KX250F’s inner fork tubes are titanium nitride coated to reduce friction. Lower friction 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 Kawasaki dirt bikes 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 motocross riders want and need, and locates the engine, rider and pivot points where they perform best.

Designed with rider ergonomics foremost in mind, the 2011 KXF 250 ’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 Kawasaki dirt bikes.

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 2011 KXF 250 package is every bit as impressive as the engine and chassis. Aside from the excellent fit and finish you expect from the engineers responsible Kawasaki dirt bikes, 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 2011 KXF 250 ’s amazing on-track abilities.

Racers who ride their KX250F Kawasaki Dirt Bikes 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.






2010 Kawasaki KX450F Dirt Bikes:

What's new for the 2010 KX450F Kawasaki Moto Bikes?

At a glance...

* More Powerful Engine.* Revised Suspension Settings.* Refined Fuel Injection.* Still Super-Easy to Start!

Engine Overview* 449cc liquid-cooled, DOHC, four-stroke single.* Cylinder skirt strengthened to handle increased engine performance.* Right-side crankcase reinforced at lower engine mount for increased strength and durability.* A forward lean angle of 3° puts the engine in the ideal position for maximum traction.* Tuned for a broad powerband with the torque curve set just under the wheel spin threshold.* High-acceleration cams help the engine rev quickly.* Maintenance free screw-type automatic cam chain adjuster.* Large flap inside the airbox helps prevent the ingress of mud and water.

New Bridged-Box Bottom Piston* Kawasaki Dirt Bike engineers are first to offer production use of a bridged-box bottom piston design.* The new piston design is same as used on Factory Kawasaki Dirt Bikes offering improved performance at all rpm.* The new 2010 KX450F piston is 7 grams lighter than the '09 piston.* 6mm shorter piston skirt features a low-friction coating for reduced mechanical losses.* Reinforced external ribs for added strength and durability.* Revised profile with fully flush internal bracing, results in a lighter, stronger piston design.* Shorter piston pin has a smaller inner diameter for increased strength.

Cylinder Head* Kawasaki dirt bike engineers designed a new intake camshaft featuring a revised sprocket/shaft arrangement. This new design advances intake valve timing by two degrees, to suit revised engine characteristics.* 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* Kawasaki dirt bike engineers designed a new crankshaft with a slightly higher inertial mass which helps boost rear wheel traction.* Wedge-shaped crank web provides enough offsetting moment for a 60 percent balance factor - this is similar to the crank balance in Kawasaki Dirt Bikes factory race engines.* End result is 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* Fuel-Injection self-adjusts to atmospheric changes for easier starting, sharper throttle response and optimized power, and power stability when jumping/landing.* Ultra-fine atomizing injector with 12 holes sprays particles with a droplet size of 60µ for smooth power deliver and smooth 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.* Fast-idle knob on the throttle body allows riders to increase engine speed when starting a cold engine.* Fuel injector set at 45°, 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 by Kawasaki Dirt Bike engineers for motocross use. The fuel pump relay is integrated with the ECU to help cope with the sever shocks and vibrations of moto racing.

Lightweight Aluminum Fuel Pump* Fuel pump is located in the fuel tank.* 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.* Fuel return hose from the pressure regulator helps ensure there is always fuel in the inlet port. This feature prevents stalling due to fuel splashing and enables moto racers to use all the fuel.* 1.8 gallon fuel tank is formed using a rotational molding process.

Optional User ECU Setting Tool* Allows Kawasaki dirt bike racers to reprogram the ECU's data maps for the volume of fuel injected and ignition timing to alter engine characteristics to suit rider preference. It is not necessary to re-tune (no changing needle jets to suit climatic conditions) like on a carbureted model.* The ECU 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.* Kawasaki dirt bikes are 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.

Better Cooling* New radiators are 10mm taller and 7.6mm wider, with increased fin and tube pitch to provide a extra strength and better resistance to mud build-up.* High-capacity Denso radiators feature tightly packed cores and a fin design that delivers superior cooling efficiency.* Because the new radiators are stronger, reinforcing brackets could be eliminated, resulting in lower overall weight.* New shrouds feature a slightly slimmer design that is fine-tuned to accommodate the new radiators.* Radiator louvers feature four small blades set at a shallow angle, for minimum overlap and maximum air flow.

Improved Clutch* New clutch provides a more direct feel and increased control.* Material trimmed from the spring holders and outer surface of the plate, to optimize rigidity and improve oil drainage, contributing to more direct feel.* Friction plates feature approximately 75% more friction material, contributing to a more direct feel.* Operating plate pusher features an increased outer diameter, to reduce the clearance between the pusher and the input shaft hole, improving clutch operation.

Close-Ratio 5-Speed Transmission* Kawasaki dirt bike engineers have provided the perfect combination of 5-Speed close-ratio transmission and low-rpm engine response. This combination offers riders more gear options for traversing through rough sections or getting into the rhythm of a course more easily so the rider can focus more on racing.* New chain with thinner inner links offers 20g weight savings.* Sprocket-style chain drive roller reduces the effect of driveline lash. This feature helps smooth engine braking and facilitates additional corner entry control.

Exhaust* Single-piece stainless steel exhaust pipe is 40mm shorter than the '09 KX450F Kawasaki Dirt Bikes, contributing to improved mid-high rpm performance.* Optimized exhaust routing contributes to improved ergonomics.* High volume silencer body helps meet noise regulations (currently 99dB).* Right side panel has special passageway to help cool the silencer.

Powerful Disc Brakes* Revised rear brake pad material offers stronger 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* New steering stem shaft with lower rigidity contributes to lighter 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 down tube that is now formed with a swaging (squeezing and hammering) process.* Swingarm pivot is located high in the frame to maximize rear wheel traction.

Aluminum Swingarm* Revised cross-section contributes to lighter handling.* Kawasaki Dirt Bike engineers have designed a tapered "D" shape swingarm. This design 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.* Revised Uni-Trak rear suspension linkage ratio increases rear traction performance.* Suspension arm is mounted below the swingarm, to allow a longer rear suspension stroke and more precise tuning.

Front Forks* Race-oriented suspension settings offer maximum over-all performance.* Revised spring rate and damping settings work with the less rigid steering stem to 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 outer tubes contribute to smooth suspension action (especially at the initial part of the stroke) and a superb ride feel.* Wrap around black fork tube guards offer effective protection for the inner fork tubes.

Rear Shock* Kawasaki dirt bike engineers have implemented new spring rate and damping settings to increase chassis stability and improve impact performance when landing 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 2-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 Factory Kawasaki Dirt Bikes.* Wide 50mm foot pegs 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 which 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 smooth sides for excellent rider mobility.* Kawasaki dirt bikes offer Skid Plates made of resin material for 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.* Rear caliper guard helps protect the caliper from damage.* Ribless rear hub and butted spokes offer light weight and excellent durability.

2010 KX250F Kawasaki Dirt Bikes:

Improvements for new 2010 KX250F Kawasaki Dirt Bikes include:

* Increased engine performance and durability. * First mass-production use of a high-performance piston featuring a bridged-box bottom.* Durable stainless steel exhaust.* Quicker-turning chassis.* Chassis balance and suspension settings aimed at race-experienced riders.

Higher Performing, High-Revving Engine* 249cc, liquid-cooled, four-stroke, four-valve, single-cylinder DOHC engine delivers hard-hitting power from mid- to high-rpm.* Engine tuned to achieve the widest possible torque band. Kawasaki dirt bike engineers carefully tuned the performance so that traction is maximized through a greater percentage of the rev range.* Race-experienced riders will be able to harness its 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.* Hot start system permits quick starting when the engine is hot; the hot start lever is unitized within the clutch lever assembly, reducing handlebar clutter.* Crank web design increases offsetting moment for a high crankshaft balance factor with the balance factor on par with the Factory Kawasaki Dirt Bikes. This feature results in reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range.

New Piston* New lighter, stronger piston shares the same design as the Factory Kawasaki Dirt Bikes. The new piston features a revised profile with a shorter skirt, reinforced external ribs and the first mass-production use of a bridged-box bottom (featuring fully flush internal bracing).* Shorter piston pin reduces reciprocating weight.* Through a revised piston crown, combustion is improved and cylinder height was increased accordingly to maintain compression ratio at 13.2:1.

Lightweight and Efficient Top End* Lightweight, highly rigid, titanium 31mm intake and 25mm exhaust valves reduce reciprocating weight and offer greater high-rpm reliability.* Kawasaki dirt bike engineers have implemented ultra-light valves. These high performance components have extremely thin valve stems on par with those found in supersport machines. The intake valves features thicker heads for increased strength.* Intake ports designed for peak performance at all rpm, especially in the high-rpm range.* Special coating applied to the intake port cores during the casting process gives the intake ports extremely smooth surfaces and optimum intake efficiency across the rev range.* Cam chain tensioner spring reduces mechanical loss by approximately 30 percent.* Increased auto-decompressor spring preload on the exhaust cam for easier starting.* Silicon coated head gasket provides excellent sealing.

Enhanced Durability and Reliability* Kawasaki dirt bike engineers chose to implement an Electrofusion treatment on cylinder bore which improves surface oil retention. Additionally a Molybdenum coating on the cylinder bore surface helps resist scorching, further contributing to durability.* Big-end bearing widened from 18 to 19mm; it features a thicker copper plating on its cage and a longer crank pin for increased reliability.* Revised oil pump rotors offer increased reliability and durability; a larger feed pump rotor size increases oil flow, while a smaller scavenge pump rotor reduces mechanical loss.

New Stainless Steel Exhaust Pipe* New stainless steel construction features a revised shape and extra durability.* Revised joint between the exhaust pipe and muffler for improved sealing and increased durability gained by using a rubber damper collar on the rear silencer mount.* Longer head and shorter mid section on the tapered exhaust pipe for increased low-rpm performance.* Kawasaki dirt bikes also meet the 99dB AMA noise regulations.

Stronger Cooling* Kawasaki dirt bikes feature new 10mm thicker and 4mm wider radiators have increased fin and tube pitch, are stronger, offer improved resistance to mud build-up and provide better cooling performance.* The stronger radiators mean the reinforcing brackets could be eliminated and overall weight reduced.* Cylinder head water jacket routes coolant via the front of the cylinder head for even cooling.

Increased Shifting Reliability* Kawasaki dirt bike engineers have implemented larger dogs on the third and fourth input gears to help prevent wear. A revised fourth input gear holding method (by eliminating a circlip and washer and changing the shape of the second input gear) also reduces thrust clearance.* New stronger crankcases feature additional material around the engine mounts and help increase long-term durability.* Ratchet drive shift mechanism provides good shift feel and transmission durability.* The clutch cable holder is integrated with the crankcase for improved feel at the clutch lever.* Scavenge oil filter screen can be accessed without splitting the crankcases, facilitating easier maintenance.

Quicker-Turning Chassis* Utilizes a new steering stem with lower rigidity for lighter handling.* The Kawasaki Dirt Bikes slim and lightweight aluminum perimeter frame construction 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 sides of the head cover, increasing rigidity.

Race-Oriented Suspension* Kawasaki dirt bike engineers have revised suspension settings to optimize front/rear balance. This results in a flatter (less forward-leaning) chassis posture when riding.* Further, revised damping settings and a less rigid steering stem offer improved action (smoother) and increased absorption performance.* Showa twin-chamber fork keeps oil and air in separate chambers for stable damping performance during long motos.* Super-hard titanium coating on the outer surface of the inner fork tubes reduces stiction and improves suspension action. The increased surface hardness of the dark navy blue coating also helps prevent scratches and damage to the tubes.* Friction-reducing Kashima Coat on the inside of the outer fork tubes contributes to smoother suspension action, especially during the initial part of the stroke.* Wrap-around black 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 tank cylinder 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* Kawasaki dirt bike engineers have provided a redesigned swingarm featuring a revised cross-section, wall thickness and internal ribs. These features offer improved cornering performance, enabling lighter turn-in and tighter cornering.* 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 a longer rear suspension stroke and more precise tuning.* Revised linkage ratios for the new Uni-Trak rear suspension to match new rear shock damping settings to achieve maximum rear wheel traction.

Rider Interface* Designed with rider ergonomics in mind, bodywork components offer the rider a slim interface, the natural position making it even easier for racers to go fast.* Formed using a double-injection molding process, the 2-tone shrouds were fine-tuned to accommodate the new radiators, and feature a slightly slimmer design.* Side number plates also 2-toned and contribute to the slim package.* Right side panel has an added passageway to aid in cooling 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 firmer urethane which keeps its original shape longer.* Seat has a slip-resistant top surface for good grip when seated and smooth sides for excellent rider mobility.* 50mm wide (front-to-rear) footpegs designed to offer grip and superb 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* New rim design with revised cross section offers both increased strength and lighter weight.* Rims are coated in black alumite - just like the Factory Kawasaki Dirt Bikes.* New thicker and more rigid front fender.* Revised rear brake pad material offers stronger braking performance.* Front and rear petal disc brakes help reduce unsprung weight, and the wave shape helps clean the brake pads for more efficient braking performance.* Rear caliper guard protects the 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 and black plastic covers, triple clamps, number plates, and engine covers.

Additional Features* Large front brake lever boot offers increased protection against debris.* Slim and compact 34mm wide chain guide, utilizes a thick wear pad for longer life.* Large resin skid plate offers great protection with minimum weight.* New chain with thinner inner links provides 20g in weight savings.

Optional Parts* Optional 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.

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