ENGINE

• New throttle body and fuel injector angle, for increased

torque feeling throughout rpm range

• New fuel pump with increased output pressure
• New intake boot
• New intake camshaft
• New cylinder head with revised intake tract and compression ratio (13.4:1)
• New exhaust header with longer and larger piping

Highly acclaimed for its high output and smooth power delivery, the KX250F motorcycle is back with new tuning and improved performance. Tuned to best suit race-experienced riders, the 249cc liquid-cooled, 4-stroke single’s wide power-band focuses on high-rpm performance that extends way into the over-rev. Riders will feel more power from low to high rpm, and experience improved over-rev characteristics.

Entering its second year after a major redesign, Kawasaki engineers concentrated on fine-tuning the 2018 KX250F’s performance in multiple ways. The intake path has been revised with a shorter intake funnel and redesigned duct. Intake valve timing has also been advanced. The KX250F features a new fuel pump with increased output as well as a new injector placement angle, bringing more precision and improved performance. The Fuel Injection system and ECU also now have revised settings, providing performance the rider can feel at the flick of the throttle. The exhaust header is now larger and longer, further increasing torque and power output, while retaining the resonator chamber.

These changes have improved the power feeling from ultra-low to high rpm—the engine feels stronger at all rpm. The 2018 KX250F motorcycle also features improved over-rev characteristics, resulting in less rpm drop when shifting, keeping the bike in the sweet spot of power while trying to cut the fastest lap possible. While power and torque have improved, the KX250F is also now easier to use in high-rpm operation.

The dual-injector fuel injection system of the KX250F is a key component to its performance; the 2012 KX250F was the world’s first production motocross bike to use such a system. Unlike a standard fuel injection system, which uses one injector downstream of the throttle valve, the system on the KX250F motorcycle uses a second, upstream injector located close to the airbox. The downstream injector is used to help ensure smooth, instant response featuring a finer atomization with more holes in the injector itself. The downstream injector creates that stronger low-to-mid range power and quick throttle response, while the upstream injector is charged with providing top-end power.

As rpm and throttle position increase, primary operation switches from the downstream injector to the upstream injector, depending on whether in a low (1^st, 2^nd) or high (3^rd, 4^th, 5^th) gear, the transition is gradual and seamless. The upstream injector’s greater distance from the combustion chamber gives the fuel particles and intake air more time to mix, as well as allowing the mixture to cool before entering the combustion chamber, both of which contribute to more efficient filling, and ultimately more power.

TUNING

• Lightweight ECU, with revised settings
• DFI^® Connectors activate three separate engine tuning maps (standard, hard, soft)
• Optional KX FI Calibration Kit (Handheld) requires no tools, laptop or battery

The lightweight ECU of the KX250F motorcycle was designed specifically to withstand the rigors of motocross racing, while still providing a wide variety of tuning options. The Kawasaki KX250F provides three engine maps that come pre-loaded into the motorcycle’s ECU that are easily accessible through the DFI® coupling plug. These three color-coded couplers are designed to tune for hard, medium or soft track surfaces, and allow riders to find the ideal power delivery for a particular terrain.

Using the optional KX FI Calibration Kit (handheld), sold separately as a Kawasaki Genuine Accessory, a rider can store and select from up to seven separate engine maps. The kit includes a portable handheld calibration tool, which enables riders to make changes to the engine maps without the need of a PC, laptop or battery, making it easy to tune at the track. The handheld calibration module plugs in thanks to an additional harness not included in the kit.

FRAME & SUSPENSION

• Lightweight, aluminum perimeter frame design
• Showa 48mm Separate Function Front Fork (SFF Type 2)

Unchanged since the introduction of a new frame in 2017, the slim chassis design contributes to light, nimble handling. The flat seat makes it easy for riders to shift their weight, offering a high level of riding freedom. New for 2018 are fine-tuned front and rear suspension settings that deliver improved bump absorption, which result in improved handling. Kawasaki test riders found improved times in tight and open sections of the Kawasaki test track.

Up front you’ll find revised Showa 48mm Separate Function Front Forks (SFF Type 2) with works-style internal construction that locates its damping assembly in the left fork tube and a spring in the right. The Separate Function Front Fork construction contributes to a planted feel at the front, superb damping performance and ride comfort with greater bottoming resistance. It also has excellent agility when on the brakes or when landing jumps. For 2018, revised settings contribute to greater precision over braking bumps and through corners.

The Uni-Trak® rear suspension with Showa shock features revised settings, new for 2018. These changes contribute to improved ride feel, traction, and increased rear-end feedback. The rear shock linkage mounts are below the swingarm to maximize wheel travel and cornering stability. Dual compression with high and low speed adjustability offers a wide range of tuning options. Self-lubricating Kashima coating on the inner shock body improves wear resistance and shock action.

LAUNCH CONTROL

The KX Launch Control system is a major advantage in getting out of the starting gate straight and fast. Launch Control Mode has the greatest effect within the first few seconds of releasing the clutch off the start.

The KX250F features a Launch Control system that, with the simple press of a button, allows riders to activate a separate engine map designed to assist starting in certain conditions. The Launch Control Mode map retards ignition timing, allowing tires to gain grip in low-traction situations, and allows riders to focus on their lines. Launch Control remains active through first and second gear, until the rider shifts into third gear, and then it returns to normal engine timing.

Even for top-level riders, controlling the hard-hitting power of a KX250F motocrosser off the start requires a high degree of throttle control and clutch finesse. By optimizing this power, Launch Control Mode helps riders maximize traction, increasing the chance of getting a good start.

BRAKES

Contributing to the racing components found throughout the KX250F are the brakes. Up front is an oversized 270mm Braking® brand rotor, which delivers strong braking force and superb control. The petal style discs contribute to both sporty looks and help deflect debris. Rear caliper guard helps protect the caliper from damage.