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

• First mass-production use of a bridged-box bottom piston design

• Same design as used on our factory racers, offers improved performance at all rpm

• 7 grams lighter than the ’09 piston

• 6mm shorter piston skirt features a 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

• Shorter piston pin has a smaller inner diameter for increased strength

Cylinder Head

• New intake camshaft features a revised sprocket/shaft arrangement which 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

• New crankshaft with a slightly higher inertial mass 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’s 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

• 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 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°, the optimum angle for mid-range power

NEW FEATURE: 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

Lightweight Aluminum Fuel Pump

• 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, preventing stalls due to fuel splashing and enabling riders to use all the fuel

• 1.8 gallon fuel tank is formed using a rotational molding process

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 preference – it is not necessary to re-tune, no changing needle jets to suit climatic conditions like on a carbureted model

• 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

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

• 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

• New chain with thinner inner links offers 20g weight savings

• Sprocket-style chain drive roller reduces the effect of driveline lash, helping smooth engine braking and facilitating additional corner entry control

Exhaust

• One-piece stainless steel exhaust pipe is 40mm shorter than the ’0 9 unit, 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

• 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

• 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 Fork

• 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 contributes 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

• New spring rate and damping settings contribute to increased stability and improved 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 Kawasaki’s factory teams

• 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

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 while on the fly

• Rear caliper guard helps protect the caliper from damage

• Ribless rear hub and butted spokes offer light weight and excellent durability

Engine

Liquid-cooled, four-stroke single with DOHC and four valves

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

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, 22-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

13.4 in

Seat height

38.0 in.

Curb weight

250.4 lbs.

Fuel capacity

1.9 gal.

Color

Lime Green

MODEL YEAR

2010

Race-Oriented Suspension

• 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

• Frame has a new 6 mm slimmer overall width main spars shape

• narrowing near the bend below the seat for a riding position, then widening at the ankles to offer better grip

• Newly designed main, lower and gusset pieces around the fuel tank with revised cross sections

• Rigidity increased by moving upper engine mounts to sides of the head cover

• New design is 2.2 lbs lighter than previous model

• Weight savings and rigidity balance aided by down tube with a smaller cast bracket that’s now formed via a swaging (squeezing and hammering) process

• Swingarm pivot is located higher in the frame for improved rear wheel traction

• Sub-frame is 1.3 pounds lighter via larger diameter tubing with thinner walls, yet still provides a secure mounting for the new silencer

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 separatel

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.

Model Year

2010

Color

Lime Green