EXHILARATING POWER AND CONTROL
Whether its power-to-weight or power and control, the KTM 250 SX is the perfect combination of all that counts. Featuring the latest high-performance 2-stroke engine fitted within a state-of-the-art chassis, this powerhouse is undoubtedly the fastest 250cc 2-stroke on track. This proven race weapon is the right choice for those who thrive on that glorious 2-stroke sound while smashing out one hot lap after the next.
ENGINE & EXHAUST
The engine of the KTM 250 SX features the latest 2-stroke technology with a counter-balance shaft for low engine vibration, as well as a reliable hydraulically operated DDS clutch. It has a twin-valve controlled-power-valve, which is a major factor in making the KTM 250 SX engine the most competitive 2-stroke in its class. Further refinements to the cylinder and exhaust, make powering through its 5-speed transmission a truly exhilarating experience.
The cylinder on the KTM 250 SX has a bore of 66.4 mm and is fitted with a Twin-Valve powervalve system. For 2019, the exhaust port has been machined to provide more precise power valve function, improving overall power delivery. By using two supplied springs, the power characteristics can be changed quickly and easily, ensuring the optimal settings for different tracks and rider preference. The lateral cylinder head brackets are now made of aluminum instead of steel and reduce vibration to levels of insignificance.
CRANKCASES AND ENGINE COVERS
The compact engine cases are manufactured using a high pressure die-cast production process that helps with weight reduction, while retaining strength and durability. The design allows for optimal shaft arrangements closer to the center of gravity, resulting in perfect mass centralization and easier ride-ability. Plus, the new engine covers feature a smart surface structure that reduces wear caused by the riderâ€™s boots, keeping them looking as fresh as the day you bought it.
The engine has a strong 5-speed gearbox built to suit any kind of motocross track. The gear ratios were developed specifically to match the power delivery of the 250cc engine. The gearbox also features a NO DIRT gear shifter. Similar to the foot peg design, it prevents the build-up of dirt and ensures the next gear is always available, no matter what the conditions.
No more numb hands and feet. This engine design allows for the addition of a lateral balancer shaft, which helps keep engine vibrations to a minimum. This means you can keep charging harder, for longer.
The KTM 250 SX is fitted with the extremely durable, KTM-developed DDS clutch (damped diaphragm steel), with a wear-free steel basket and heat resistant clutch plates. It uses a diaphragm spring instead of the usual coil springs, which results in considerably easier clutch action. The diaphragm spring is also compact enough to allow for a damping system to be integrated into the clutch hub, contributing to better traction and durability. Additionally, the Brembo hydraulic system provides easy and precise clutch modulation.
The KTM 250 SX is fitted with a MIKUNI TMX carburetor. The settings on the 38 mm flat slide carburetor have been adapted to suit the new airbox and exhaust design, providing smooth, controllable power all the way through the rev range.
All 2-stroke models feature a new CDI control unit with an advanced hardware which improves the starting behavior of the engine. The ignition curves remain unchanged.
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 250 SX features newly designed radiators which are mounted 12 mm lower than the predecessors. This lowers the center of gravity and matches the design of the new shrouds perfectly, in order to achieve perfect ergonomics. By using CFD technology (computational fluid dynamics) together with a clever coolant circuit routing, the innovative system ensures the optimum engine temperature for the highest performance, no matter what the conditions. The radiators also feature special protectors that donâ€™t only serve as protection from flying rocks and debris but also as a brace that disperses energy around the radiators in the event of an impact.
At the heart of the engine, the crankshaft features a 72 mm stroke that produces the optimal torque and revs. It has been ideally balanced and with the aid of the counter balancer shaft, resulting in minimum vibration. The crankshaft is placed in the perfect position to centralize mass, contributing to better agility and handling.
When it comes to improved power delivery and performance, the new exhaust plays a key role and packs a punch that is hard to beat. In addition, its new shape provides slimmer ergonomics while still operating safely within the noise limits for racing.
The chassis forms an integral part of the feeling a rider has with his bike. The new chassis on the KTM 250 SX is designed to provide accurate feedback between the track and the rider, while also reducing the harshness of typical motocross terrain. The new lightweight, high-tech steel frame is made from chrome-moly and features optimized flex characteristics that soak up those big hits while also delivering excellent agility and high-speed stability. For 2019, the engine has been raised in the frame by 1° around the swing arm pivot, improving the handling and the grip of the front wheel. The refinements on this new chassis ensure the KTM 250 SX remains one of the most thrilling rides out there.
The frame on the KTM 250 SX is brand-new and crafted from hydro formed Chromium Molybdenum steel tubes. It is robot welded for better consistency and improved quality. The improved stiffness has been specifically tailored to balance agile handling and comfort. The revised frame is designed to work in unison with the suspension for excellent high-speed stability. The frame also features "no-dirt" footpegs which have a simple but effective self-cleaning system that ensures the footpegs return to their original position, providing complete control in all conditions. The engine in the KTM 250 SX frame has been raised by 1° around the swing arm pivot, improving the handling and the grip of the front wheel. New aluminum headstays drop weight further. For 2019, all SX frames feature the same highly durable powder coating as the KTM Factory machines and come with standard frame protectors. The lightweight aluminum subframe is 40 mm longer to improve rear fender stability.
The KTM 250 SX features an improved one-piece swing arm with 5 mm longer axle slots that allow greater wheelbase adjustment to suit varied conditions for tight turns on SX type tracks, or more straight-line stability when it gets fast and rough. Manufactured with a gravity die-cast process, the swingarm has exceptional strength at the lowest possible weight. The chain measurement markings on the swingarm are visible from above, making chain adjustment simpler and more accurate.
KTM uses lightweight, CNC-machined hubs and high-end Excel rims on all SX models, guaranteeing maximum stability and minimum weight. For 2019, the aluminum spoke nipples feature a reworked design, which conveniently reduces the frequency with which the spokes need to be tightened. The wheels are fitted with the latest Dunlop Geomax MX 3S tires, delivering maximum grip and stability and effectively transferring all the power to the ground.
All full-size SX models are fitted with the super-lightweight WP AER 48 front fork. It is a 48 mm USD air-sprung fork with separate functions for each fork leg, meaning damping functions are on the right side and the air spring is on the left. The left leg features a two-chamber system with a capsuled air cartridge, helping prevent loss of air pressure. Essentially, this means that in the rare case of a leaking outer seal, the internal cartridge pressure keeps the bike in a normal position. The air spring is exceptionally easy to use and can be adjusted to any rider weight via a single air valve and the air pump that is supplied with the bike. The right fork leg integrates a damping cartridge to fit single damping leg requirements and can be adjusted to the track conditions and the rider's preferences. (compression from top, rebound from bottom, 30 clicks each). For 2019, new settings on the damping side have improved the damping characteristics, providing great front end feel and control.
All SX models feature a DDC monoshock, which has been developed to work as a complete unit with the entire frame and swingarm architecture, as well as the linkage system and the AER 48 forks. It features high-quality machined and anodized components, which add a touch of class and give it appeal beyond just a functional necessity. Internally, the shock houses an updated main piston and new settings that provide improved damping characteristics, perfectly complimenting to the reworked front-end setup. It is fully adjustable, including high and low speed compression, allowing you to set the shock up precisely to suit any track and rider's preferences.
All SX models feature top quality, CNC-machined triple clamps and have become somewhat of a KTM trademark. For 2019, the triple clamp has been reworked with stiffer upper clamps (22 mm offset for all models) to suit the reworked frame stiffness and flex characteristics of the latest WP AER forks. The result is a front end that works in perfect harmony with the frame, improving overall handling and stability. The rubber damped handlebar fixation reduces vibration and also allows for some adjustment with 2 different mounting positions. An hour meter is fitted as standard on the upper triple clamp on all SX models, keeping the rider informed of the number of hours spent tearing up the track and when the next service is due.
High-tech Brembo brakes have always been standard equipment on all KTM motocross bikes. Combined with lightweight wave discs, the renowned system provides the highest level of braking efficiency, enabling you to out-brake the competition.
All models in the SX range are fitted with newly designed lightweight polyethylene fuel tanks. The fuel capacity on the full-size SX models is still 7 liters, but the new shape improves the ergonomics. The filler cap has an inside thread that makes for easy and reliable closure.
The new airbox on the KTM 250 SX has been completely reworked to ensure better flow dynamics, and together with new intake snorkels, leads to optimal power and throttle response. Despite the obvious performance enhancements, the new design also offers maximum protection against soiling of the air filter. The large Twin-Air air filter is mounted on a cleverly designed stiff cage that minimizes incorrect installation. As found on previous models, filter maintenance is quick and easy and does not require tools - a standard, original feature from KTM.
ERGONOMICS & COMFORT
A rider's ability to work in unison with his bike depends on how quickly and effectively he can shift his weight around the motorcycle. KTM has focused extensively on creating bodywork and ergonomics that allow for the highest levels of performance. This ensures the natural riding position offers the best possible control and, through various handlebar positions, can also be adjusted to suit every rider and condition. A rider's main connection to the motorcycle comes through the seat, footpegs and handlebars and these three touch points play a vital role in maintaining balance and control. A rider is always looking for a fast and competitive motorcycle with a great feeling of controlled agility. The 2019 KTM 250 SX, like the entire SX range, ticks all the right boxes, especially when it comes to race-ready ergonomics.
All SX models have a newly shaped seat, designed to match the improved ergonomics. The seat cover features newly developed silicone strips that provide better feel and grip for the rider. The seat is conveniently fixed to the bike using one long, lateral screw, making it safe and easy to handle.
All full-size SX models are equipped with the same high-strength aluminum tapered handlebar, made by NEKEN. The handlebar is fixed in rubber damped mountings, which allow for two different positions. The handlebars come standard with an ODI vulcanized grip on the right side and a comfortable ODI lock-on grip, which does not require any wire or glue, on the left. They also feature a reworked bar-pad with a newly designed cover that can be attached and removed a lot quicker and easier. These handlebars give the rider the ability to take control on the track, as well as the grip to hang on through that awesome 2-stroke powerband.
Sophisticated 'No Dirt' footpegs prevent smudging up the pegs, even when digging in deep ruts. Looking for a higher riding position? Then just mount the footpegs of the MY2018 EXC models, which are 6mm higher than the SX versions.
BODYWORK & GRAPHICS
The KTM 250 SX has become an icon amongst 2-stroke fanatics, but for this bike, the classic sound it produces is where the nostalgia ends. A combined effort between KTM's factory riders, KTM R&D and Kiska Design has resulted in a highly effective modern-looking motorcycle with bodywork that achieves complete harmony between rider and bike. When designing the 2019 SX range, the main goal was to provide the perfect contact points for the rider, allowing maximum freedom of movement and improved motorcycle control. Examples of the intelligent design can be seen in the Ibeam structure of the front and rear fenders, which guarantee maximum stability and the lowest possible weight. The modern design and graphics ensure that it is not only about function, but an impressively fast and aggressive look that sends a clear message to the competition.
The 2019 SX models feature the latest in-mold graphics, matching the new bodywork perfectly. They have a fast and aggressive style that screams READY TO RACE, leaving no doubt as to the bikes' high-performance intentions.
SOFTWARE & ELECTRONICS
Absolute performance purity is the name of the game when it comes to electronics and the new KTM 250 SX. Undiluted 2-stroke simplicity, with an hour meter to keep a check on how long you've been shredding and an optional rev counter to assist with perfect setup.
1-cylinder, 2-stroke engine
Wet multi-disc clutch, hydraulically actuated
25CrMo4 steel central-tube frame
WP-USD, AER 48, Ø 48 mm
WP shock absorber with linkage
Suspension travel (front)
Suspension travel (rear)
Front brake disc diameter
Rear brake disc diameter
5/8 x 1/4"
Steering head angle
Tank capacity (approx.)
Weight READY TO RACE (without fuel)
The illustrated vehicles may vary in selected details from the production models and some illustrations feature optional equipment available at additional cost.
All information concerning the scope of supply, appearance, services, dimensions and weights is non-binding and specified with the proviso that mistakes, printing, setting and typing errors may occur; such information is subject to change without notice.