Kawasaki's KX250F motocrosser had a victorious year, winning on the track and topping its class in numerous enthusiast magazine shootouts. The successful mix of the highly rigid aluminum frame and top-shelf suspension components deliver superb high-speed stability, while its chassis geometry and high-revving engine offer excellent rear wheel traction and holeshot-winning performance. Sebastian Pourcel used his new Monster Energy/ Pro Circuit / Kawasaki KX250F to win the AMA East Supercross Lites Championship and then continued his winning ways into the outdoor season. But in the volatile world of racing, it's a constant challenge to stay on top.

To ensure it continues its podium-topping tradition, Kawasaki fine-tuned the light handling KX250F for 2010. The engineers capitalized on its solid foundation, with refinements focused on increasing performance and longevity. The result of their labors will help the KX250F add to its ever-growing trophy collection. Borrowing from the racing world, the KX250F gets a new piston with a bridged-box bottom – making its first appearance in a mass-production machine. The new piston is lighter and stronger. It also has a revised profile with a shorter skirt and shorter piston pin, which reduces reciprocating weight. It also features a revised crown that improves combustion. The cylinder height was raised accordingly to maintain the 13.2:1 compression ratio. Low-rpm performance was bumped up via a new longer head pipe and shorter mid-section on the new, more durable stainless steel exhaust pipe.

The 249cc, liquid-cooled, four-stroke engine received a number of other refinements for 2010, such as electrofusion treatment on the cylinder bore, revised oil pump rotors and a wider big-end bearing to increase engine life.

Its crank web design produces a crankshaft balance factor of close to 60 percent, on par with Kawasaki's factory racers. The result is reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range. Tuned to deliver the widest possible torque band, the KX250F engine offers traction in a controllable, class-leading manner from the first crack of the throttle to wide-open at the rev limiter.Like its bigger sibling, the KX250F received larger, stronger radiators with increased fin and tube pitch that accumulate less mud and provide more consistent cooling. With the extra strength in the new radiators, the reinforcing brackets could be dropped, helping reduce the weight of the entire radiator assembly.

Transmission durability was also raised inside and out. Building upon the achievements of last year, Kawasaki engineers put larger dogs on the third and fourth input gears to help prevent wear, and revised the fourth input gear holding method by eliminating a circlip and washer and changing the shape of the second input gear to reduce thrust clearance. On the outside, the new KX250F crankcases are stronger and thicker with increased material around the engine mount holes. The transmission action and feedback are optimized with its ratchet drive shift mechanism and integrated clutch cable holder into the crankcase.

With its lightweight construction blend of forged, extruded and cast parts, the KX250F's slim aluminum perimeter frame has the chassis balance and settings race-experienced riders seek. The center of gravity and locations of key items such as the swingarm pivot, output sprocket and rear axle were positioned to best channel the drive from the rear tire into forward acceleration.

For 2010, chassis improvements are primarily focused on delivering sharper cornering performance and an optimized front-to-rear balance for improved suspension composure. To achieve this balance, the race-oriented suspension settings were revised for a more balanced – less forward-leaning – chassis posture when riding. A new steering stem with lower rigidity helps lighten handling, while also providing smoother fork action and better impact absorption.

These revisions refine the stable damping performance of the KX250F's Showa twin-chamber fork during long motos and work in conjunction with the updated swingarm, which features a modified cross-section with thinner wall thickness and narrower internal ribs. The Showa rear shock's new damping settings provide greater stability and less "kicking" on corner entry. New Uni-Trak rear suspension linkage ratios match these new rear shock damping characteristics.

Designed with rider ergonomics in mind, the KX250F bodywork offers riders a slim interface and a natural positioning that make it easier to go fast. The sleek bodywork components include one-piece, dual injected, two-tone black and green plastic shrouds and side number plates. The shrouds were fine-tuned to fit the new radiators while retaining their slender form. For 2010, a thicker and more rigid front fender graces the KX250F. The slim, rider friendly seat with a non-slip top surface and smooth sides provides excellent seated grip and rider mobility, and gets firmer urethane foam to hold its shape longer.

Chassis protection is grade-A for 2010, and helps sustain the KX's durability factor. Examples include the large, resin skid plate, the rear caliper guard and the narrow, long-lasting chain guide, all of which offer protection without high weight.

The rest of the KX250F is equally impressive, with premium-quality Renthal aluminum handlebars included as standard equipment along with black triple clamps, engine covers and hubs. The new black alumite coated lightweight aluminum wheels feature a revised cross section that offers both increased strength and lighter weight, and the ribless rear hub and butted spokes further reduce unsprung weight. Factory-style graphics finish off the package and complement the KX250F's stellar on-track performance.

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.

Features and Benefits

At a glance...

• 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, so that traction efficiency 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 racers; resulting 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 racers, with 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
• The ultra-light valves have extremely thin valve stems on par with those found in supersport machines with the intake valves featuring 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

• Electrofusion treatment on cylinder bore improves surface oil retention and the 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
• Silencer meets 99dB AMA noise regulations

Stronger Cooling

• 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

• The third and fourth input gears have larger dogs to help prevent wear, while a revised fourth input gear holding method (by eliminating a circlip and washer and changing the shape of the second input gear) 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 KX250F's 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

• Revised race-oriented suspension settings optimized front/rear balance, resulting 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

• Swingarm features a revised cross-section, wall thickness and internal ribs for 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 racers
• 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

                                                                                                                                                                                                                                                                                                                                   

Engine:	Four-stroke single with DOHC and four valves
Displacement:	249cc
Bore x stroke:	77.0 x 53.6mm
Cooling:	Liquid
Carburetion:	Keihin FCR37 and hot start circuit
Compression ratio:	13.2:1
Ignition:	Digital CDI with K-TRIC throttle position sensor
Transmission:	Five-speed with wet multi-disc manual clutch
Final drive:	Chain
Frame:	Aluminum perimeter
Rake / trail:	27.4 degrees / 4.7 in.
Front suspension / wheel travel:	47mm inverted Showa twin-chamber telescopic fork with 16-way compression and rebound damping / 12.4 in.
Rear suspension / wheel travel:	UNI-TRAK® linkage system and Showa shock with 13-way low-speed and stepless high-speed compression damping, 17-way 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:	57.9 in.
Ground clearance:	13.4 in.
Seat height:	37.6 in.
Curb weight:	231.4 Lbs.
Fuel capacity:	2.1 Gal.
Color:	Lime Green
MSRP:	$6999