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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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