The KX design philosophy – to put mid-level to expert riders on the top step of the podium – has not changed since the brand was launched over 40 years ago. The KX250 has a history of winning: in the extremely competitive 4-stroke 250cc class it is the racer with the most AMA Supercross and Motocross titles. Adding to its highly acclaimed engine and chassis performance, numerous industry firsts and advanced technology, the 2019 model offers a powerful engine, a light chassis, and matched with the slim ergonomics, making the 2019 model the most competitive KX250 yet.
The KX250 was the first mass-production motocrosser to feature Showa’s Separate Function front Fork (SFF), which separates damping and shock absorption duties:
Left fork tube: damping assembly
Right fork tube: spring
The configuration offers both smooth action and firm damping performance – a combination difficult to achieve with a conventional fork.
Using large ph48 mm inner tubes contributes to greater fork rigidity, resulting in a more planted feel from the front wheel.
With only one spring, the friction generated between the spring(s) and fork inner tube(s) is greatly reduced (approximately 25% less), resulting in extremely smooth action throughout the fork stroke.
Being able to use larger damper pistons not only enables smoother action, it also makes firm damping performance possible.
The large diameter fork tubes enable larger damper components.
Main piston diameter 30 mm
Sub-piston diameter 35 mm
With the large components, the same damping force as the 47 mm SFF Type 1 can be achieved with a lower internal pressure. With the lower pressure, the 48 mm SFF Type 2 is even better equipped to offer both increased riding comfort and firmer damping performance.
.Low friction Titanium hard coating on the SFF Type 2 For
For 2019, the ultra slim frame is one of the many components contributing to the KX250’s trim form. The light weighing 2019 KX250 model is quick both in the straights and through the corners. Suspension settings for the high-spec SFF Type 2 front fork and Uni-Trak rear shock settings were determined to deliver great stability over braking bumps and through corners. A slim, flat rider interface further enhances the adjustable racer-friendly ergonomics, helping racers to rider even faster.
Large oversized 270mm front disc contributes to race winning braking power and control.
The radical design front and rear petal discs offer strong braking performance, excellent competitive edge with high quality factory looks.
High-performance piston, featuring the same design used on our factory racers, contributes to strong performance at all rpm. A short skirt, reinforced external ribs and the use of a bridged-box bottom, featuring internal bracing, contributes to a light, strong piston design. Already the lightest piston in its class, the pistons design and strength optimisation help lower reciprocating mass and contribute to the engine’s strong performance. Piston pin is offset 0.25 mm, complementing the offset cylinder and help reduce mechanical losses. Strength optimisation results in a light piston pin design. Coating and striation on the piston outer surface ensure good wear resistance and oil retention for minimal sliding friction. The molybdenum coating also helps reduce mechanical loss.
Adjusting engine settings to suit conditions has never been easier than with the KX’s FI couplers. Plug-and-play style system is quick, easy and stress-free. Instead of a single engine map, the ECU features three (four, counting the Launch Control Mode map). Initial settings for the three maps are: Standard (green), Hard (conditions)(black) and Soft (conditions)(white). Using provided FI couplers, riders are able to easily switch between the three maps to suit riding conditions. Plugging in each of the 4-pin couplers activates the corresponding engine map. (Plug is conveniently located on the right side of the head pipe for easy access without having to remove any parts.)
Each of the three maps can be reprogrammed using the optional KX FI Calibration Kit.
The updated KX FI Calibration Kit features the handheld KX FI Calibration Controller, which enables expert riders to adjust engine characteristics (by rewriting actual data maps) to suit their preference. This simple tool can be used without a PC, simply by plugging into the engine’s ECU.
The KX FI Calibration Controller is handheld tool with a built in colour LCD screen. It comes with transfer and diagnostic cables, SD memory card, user manual and a carrying case.
The KX250 features a launch control system similar to that on our factory racers. With the simple press of a button, riders can activate a separate engine map designed to ensure efficient race starts in slippery conditions. The Launch Control Mode map retards ignition timing, allowing tyres to gain grip in low traction situations.
Launch Control Mode has the greatest effect within the first few seconds of releasing the clutch off the start. This is the most crucial time for the rider to get ahead of their rivals and line up the first corner.
43 mm throttle body is both compact and light. The main injector is now mounted at 30° in the throttle body and the FI settings have been optimised for the updated engine settings.
Designed specifically for motocrossers, the fuel injection system incorporates a small lightweight ECU and operates without a battery to further eliminate unnecessary weight. And of course, fuel injection eliminates the need to adjust engine settings to suit track and climate conditions
The KX250 fuel pump, located in the fuel tank, is a lightweight aluminium construction. The fuel pump’s high 343kPa pressure matches the high performance injector.
A choice of four positions allows riders to tailor their riding position. Factory-style Renthal handlebar and pad come standard.
Upper triple clamp with two sets of handle mount slots and reversible handle mounts offers riders a choice of four handle positions to choose from: 25 mm FWD, 15 mm FWD, STD and 10 mm BK.
Tuned to best suit race-experienced riders, the 249 cm3 liquid-cooled, 4-stroke single’s wide power-band focuses on high-rpm performance and extends way into the over-rev. Highly acclaimed for its high output and smooth power delivery, the 2019 model KX250 backs up its dual-injected power and race-inspired tuning with the short downdraft-style intake duct, a large diameter and carefully tuned exhaust header pipe, matched to the optimised intake camshafts timing and the advanced dual injection EFI system results in excellent power/torque feeling make it easier to ride fast and enabling fast lap times. Bottom-end to mid-range: The strong power/torque translates to smooth power engagement, making it easier to use the power band and requiring less attention to be spent on clutch work. Top-end: Thanks to the smooth power engagement, the high-rpm range is easy to use.
Riders can choose from two positions on the footpegs to suit their body size and personal preferences.
The adjustable brackets enable riders to lower the footpeg position 5mm. In the lower position, centre of gravity is lowered as is the rider’s point of view, adding to both the physical and psychological stability.