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
