Motorcycle specifications KTM250 SX-F 2019 Above challenges

A strategic model in the motocross range, the two-and-a-half-bike SX-F returns to top form in 2019. With its many innovations, the KTM 250 SX-F will once again reign supreme on motocross tracks. Not content with being one of the lightest bikes in its class, it offers unrivalled yet perfectly controllable power delivery. That's why it appeals to amateurs and professionals alike. The secret of a good motor is its ability to handle power with maximum efficiency. This package is a real winner in this respect, and will have no trouble leading you to victory.

engine

the 250 SX-F's engine is considered one of the most powerful in the MX2 paddock. Capable of reaching 14,000 rpm without flinching, and with phenomenal torque present throughout the rev range, this engine has a lot to say for itself. Its compact architecture ensures better mass centralization and exceptional roadholding. It weighs just 25.9 kg, including electric starter.

cylinder head

the centerpiece of the compact DOHC (double overhead camshaft) engine, the new avant-garde cylinder head features two overhead camshafts titanium valves (32.5 mm intake, 26.5 mm exhaust) using ultra-light, DLC-coated rockers. For 2019, the camshaft on the exhaust side benefits from a new timing system designed to better meter power delivery.

crankshaft

the crankshaft of the KTM 250 EXC-F offers greater rigidity. The connecting-rod bearing features two bearing shells pressed directly into the crankpin. This design is the prerequisite for extremely high speeds and unrivalled power from the 250 cm³ engine. This design extends engine life and extends crankshaft service intervals, saving the customer time, effort and money.

crankcases and covers

the use of a high-pressure die-casting process results in a relatively compact crankcase that is even lighter, while maintaining its strength and durability. The design of the crankcase has enabled KTM engineers to move the shaft mountings closer to the center of gravity, so as to better centralize the masses and enhance rideability. Another interesting innovation to keep the engine as radiant as in the early days: crankcase covers with an elaborate surface structure, designed to reduce wear caused by the rider's boots.

gearbox

the KTM 250 SX-F is now equipped with a new, more robust 5-speed gearbox. The transmission ratios of the previous version have been retained, but the sprockets have all been improved and reinforced. Another highlight of the transmission is the "zero dirt" design of the selector. Designed on the same principle as the footrest, it prevents the accumulation of dust and enables the gearbox to remain operational in all conditions.

engine management

the Keihin engine management system with electronic fuel injection features a new 44 mm injection body. The unique position of the injector ensures excellent atomization of the fuel and air entering the combustion chamber. The engine is even more lively and generous when the throttle is opened. For added convenience, independent adjustment mechanisms have been provided for cold start and idle. The MAP sensor (absolute pressure sensor) has been made even more watertight, making the system even more reliable. Modifications to the throttle cable have simplified cable routing and made them more accessible. The control unit (ECU) on the 2019 models features new mappings adapted to the new exhaust and cylinder head design, with the aim of better managing traction control and starting control. To deliver maximum power, it adapts the engine's characteristics at each speed, according to the data communicated by the engaged gear sensor.

cylinder and piston

the 78 mm-bore cylinder houses a forged bridge-box piston of the highest quality, manufactured by CP. In addition to its extremely rigid structure, it features a unique crown shape to match the high level of compression in the combustion chamber. The high compression ratio (14.4:1) and reduced oscillating masses give the engine an extremely responsive character.

balancer shaft

to compensate for the inertia generated by the 250 SX-F, the engine is fitted with a multifunction balancer shaft. In addition to its beneficial effect on vibration levels, this shaft also drives the timing chain and water pump.

clutch

the new DS (Diaphragm Steel) clutch consists of a durable one-piece clutch housing and a main gear (made of ultra-high-strength billet steel), offering rock-solid reliability. It features extremely heat-resistant steel motor friction discs preloaded by a diaphragm spring. The function of this system is to optimize clutch disengagement and instantly transmit the available power to the rear wheel as soon as you release the clutch. This type of design significantly reduces the force exerted on the clutch, which is even more true with the Brembo hydraulic system.

electric starter

every minute is precious in racing. The electric starter allows you to get back into the race without wasting time. The electric starter, available as standard on the KTM 250 SX-F, uses Mitsuba's robust electric motor. The rock-solid reliability of this device saves precious starting time at crucial moments of the race.

handlebar map selector

all 4-stroke models feature a handlebar-mounted map selector for traction and start control, and for switching between power curves (Standard Advanced). Traction control is a unique function with a new setting on 2019 models. It ensures more efficient traction and better control of the bike during acceleration phases, especially on demanding tracks. This function can be activated, even at full throttle, using the map selector on the handlebars. When the engine is at idle, simply press both switches simultaneously to activate the start control as well, for a quicker jump off the grid. Thanks to a new set-up, start control can now take advantage of traction control to limit wheel slip and gain traction. In addition to the standard engine modes, the map selector gives access to other engine modes for maximum racing options.

cooling

to ensure smooth power delivery, it's essential to maintain optimum engine temperature. To this end, the KTM 250 SX-F features new radiators that are 12 mm lower than those of its predecessor. This position, perfectly matched to the design of the new spoilers, lowers the center of gravity and enhances ergonomics. Thanks to numerical fluid dynamics (CFD) simulation calculations and a clever cooling circuit, this innovative system ensures that engine components are kept at the ideal temperature to guarantee the highest level of performance, whatever the conditions. Special radiator guards not only protect the radiators from stones and other debris, but also distribute the force of impact around them.

muffler

the new exhaust system, fitted to all 4-stroke models, gives the engine a smoothness and liveliness that are hard to match. It features a new exhaust manifold (specific to the model) and a small additional chamber, i.e. an advanced resonator called FDH (Flow Design Header). The muffler benefits from a new aluminum casing and a new nozzle. The interior of the silencer has also been reworked. The new structure allows the exhaust to be disassembled without having to remove the shock absorber, and facilitates access to the latter. Another ergonomic advantage is the slimmer silhouette of the motorcycle, while respecting regulatory noise emission levels.

chassis

the KTM 250 SX-F features a new high-tech steel frame that not only optimizes rider feel, but also provides excellent feedback. The frame's flexibility has been specially designed to enhance the bike's agility and stability at high speeds, and to make the riding experience as intuitive as possible.

frame

the completely redesigned frame of the KTM 250 SX-F promotes the dynamic riding styles de rigueur in the MX2 class. As with the rest of the SX range, the chromium-molybdenum steel frame features hydroformed tubes assembled by automated welding, to guarantee the highest level of quality. Rigidity has been optimized to enhance handling. The excellent cohesion with WP suspensions offers the perfect compromise between agility and high-speed stability. And with self-cleaning "zero-dirt" footrests that won't jam when returned to position, you're in complete control, whatever the conditions. All 4-stroke frames feature three new brackets to facilitate fitting of an optional composite protection shoe (available from the KTM PowerParts range of accessories). The frame of all 2019 SX models inherits a highly resistant powder-coating (as on KTM Factory machines) and standard frame protectors. The new rear buckle, made of lightweight aluminum, has been lengthened by 40 mm to enhance mobility on the saddle and improve rear hull stability.

swingarm

the KTM 250 SX-F's new one-piece swingarm, produced by high-pressure die-casting, has been designed to offer rock-solid strength, while keeping weight to an absolute minimum. The extra 5 mm of play in the axle housing allows the wheel to be set back to improve stability on chaotic tracks. The chain measurement markings on the swingarm are visible from above, making adjustment much easier.

wheels

featuring ultra-light CNC-machined hubs and top-of-the-range Excel rims, the wheels on all SX models guarantee maximum stability despite limited weight. The aluminum spoke heads on the 2019 models have been redesigned to reduce the frequency with which spokes need to be re-tensioned. The wheels are shod with latest-generation Dunlop Geomax MX 3S tires, to maximize power transfer to the ground and enhance stability.

front suspension

all standard-size SX models feature the ultra-light WP AER 48 fork. The legs of this 48 mm inverted air fork have different functions: the damping functions are on the right, the air spring is on the left. The left fork leg features a double-chamber air cartridge system designed to prevent any loss of pressure. Should the outer seal leak, the pressure exerted inside the inner cartridge will keep the bike in its normal position. The air spring is extremely easy to adjust, and can be adapted to the rider's weight using a single valve and the air pump supplied with the bike. The right-hand fork leg features a cartridge specially designed to meet the requirements of the single-arm damping design, and can be adjusted to suit track conditions or rider preference. Simply turn the 30-step knob to the desired position (compression up and rebound down). The new damping settings on the 2019 models have improved front-end control and feel.

brakes

the latest Brembo brakes are standard equipment on KTM motocross bikes. Combined with Wave brake discs renowned for their light weight, they deliver the stopping power expected by the most daring riders.

fuel tank

all SX models feature a new, ultra-light polyethylene fuel tank. Capacity on standard-size SX models is still 7 liters, but the shape of the tank is more ergonomic. The internally threaded fuel filler cap ensures easy, reliable closure. To ensure greater reliability of the fuel pump on 4-stroke models, KTM engineers have chosen to route the hoses internally.

air filter housing

the air filter housing on the KTM 250 SX-F has been completely redesigned to optimize flow dynamics. Combined with the new intake snorkels, it ensures exceptional power delivery and acceleration. In addition to the obvious performance gains, the new design also protects the air filter from clogging. The rigid support for the large Twin-Air filter has been designed to minimize installation errors. As on previous models, the filter can be serviced in record time and without tools, a typically KTM feature.

saddle

the saddle on all SX models has been redesigned to confirm the ergonomic improvements made. The saddle cover now incorporates silicone strips to optimize grip and feel. A long screw on the side secures the saddle to the motorcycle, making handling easier and safer.

handlebars

all standard-size SX models feature the same tapered, ultra-strong aluminum handlebars made by NEKEN. Two positions are possible for the handlebar trigger guard with shock absorbers. right: an ODI vulcanized grip available as standard; left: an ODI lock-on grip that's as comfortable as it is practical, thanks to its glue- and wire-free mounting system. The handlebar foam has also been redesigned, as has the handguard, which is now much easier to fit and remove. With these handlebars, victory is within reach.

battery and wiring harness

to start the engine every time, especially in cold weather, the starter of SX-F models is powered by a new, ultra-light, high-performance 2 Ah lithium-ion battery. The voltage regulator/capacitor assembly now unites all electrical components under the seat, making the system even more reliable.

Images and info credits: KTM