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.

Details & Features

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 friction, 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

Higher Performing, High-revving 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 friction and easier adjustability
• Fork now allows external spring preload adjustability
• Super-hard titanium coating on the outer surface of the inner fork tubes reduces friction 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 System: Liquid
Fuel injection: 43mm Keihin throttle body
Compression ratio: 13.5:1
Ignition: Digital DC-CDI
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame Type: 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 Size: 80/100-21
Rear Tire Size: 100/90-19
Front brakes: Single semi-floating 250mm petal disc with dual piston caliper
Rear Brakes: 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 Choices: Lime Green