Motorcycle specifications KTM250 SX 2020 A thrill on the pitch

The KTM 250 SX is certainly the closest thing to the ideal combination of weight and power, or performance and control. With its high-performance 2-stroke engine and innovative chassis, it's certainly one of the fastest 250 cm3 2-stroke bikes on the circuit. This racing beast is the preferred choice of speed enthusiasts who love the characteristic 2-stroke sound.

engine and silencer

kTM 2-strokes have been a fixture on motocross tracks for many years, and are among the fastest motorcycles ever built. After years of evolution, these engines have become the benchmark for performance and technology, offering the ideal compromise between power, weight and control. More melodious than ever, especially at higher revs, KTM 2-strokes have captured the public's imagination and continue to thrill us today.

engine

the 250 SX's engine is the ultimate in 2-stroke technology, featuring a vibration-damping balancer shaft and an ultra-reliable hydraulic DDS clutch. The TVC exhaust valve system is a major asset of the KTM 250 SX engine, rightly considered the most competitive 2-stroke in its class. The 5-speed gearbox adds to the riding pleasure.

cylinder

the cylinder of the 250 SX, with a bore of 66.4 mm, features a TVC exhaust valve system. The exhaust outlet has been machined to ensure more precise operation of the exhaust valve control and increase overall performance levels. In addition, the engine's character can be changed quickly and easily, thanks to the two springs provided for this purpose, so that the ideal settings can be found (depending on the track or the rider's preferences). The cylinder head's side mounting lugs are made of aluminum to dampen vibrations almost completely.

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 solid 5-speed gearbox is ideal for any motocross track. Gears are perfectly matched to the power delivered by the 250 cm3 engine. The "zero dirt" design of the selector is another strong point of this transmission. Designed on the same principle as the footrest, it prevents the accumulation of dust and enables the gearbox to remain operational in all conditions.

balancer shaft

no more numb hands or feet. The engine's design has allowed the addition of a side-mounted balancer shaft that helps minimize vibration. Riding at a steady pace for long hours is therefore all the less tiring.

clutch

the 250 SX is equipped with a heavy-duty DDS (Damped Diaphragm Steel) clutch developed by KTM. This features a wear-free steel clutch housing and heat-resistant clutch plates. The use of a diaphragm spring instead of the usual coil springs makes it even more flexible. The diaphragm spring also has the advantage of being compact, enabling a damping system to be integrated into the clutch hub, for improved driveability and durability. The Brembo hydraulic clutch system is also distinguished by its precision and progressiveness.

carburetor

the 250 SX is equipped with a MIKUNI TMX carburetor. The settings of this 38 mm flat-barrel carburetor are adapted to the air filter housing and exhaust structure, to ensure a more linear, better-dosed power delivery across the entire rev range.

contact

all 2-stroke models feature a CDI gearbox and advanced components designed to improve engine starting behavior. Ignition curves remain unchanged.

crankshaft

at the heart of the engine, the crankshaft has a 72 mm stroke, ensuring superior torque and maximum power. Perfectly balanced, it is combined with a balancer shaft to minimize vibration. Ideally positioned for optimum mass centralization, the crankshaft contributes to the bike's agility and handling.

cooling

to ensure smooth power delivery, it's essential to maintain optimum engine temperature. The position of the 250 SX's radiators, perfectly matched to the design of the spoilers, lowers the center of gravity and enhances ergonomics. Thanks to CFD (Computational Fluid Dynamics) 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 exhaust system gives the engine a suppleness and liveliness that are hard to match. Its narrow design is a real plus in terms of ergonomics, while respecting the noise emission levels recommended for racing.

chassis

the chassis contributes to the feeling of osmosis between rider and machine. The chassis of the 250 SX has not only been designed to mitigate the effects of the many irregularities of motocross terrain, but also to provide excellent feedback to the rider. The high-tech chromium-molybdenum steel frame offers the flexibility needed to absorb the biggest shocks and enhance the bike's agility and stability at high speeds. On the 2019 model year, the engine had been lowered by 1° in relation to the swingarm axis, to enhance handling and front-wheel grip. The same applies to the 2020 version. Suspension damping characteristics have been optimized on the 2020 version. In particular, the suspension settings have been revised to provide extra suppleness and comfort. Combined with a high-performance, dynamic chassis, these suspensions enhance the 250 SX's exhilarating handling.

frame

the frame is made of hydroformed chromium-molybdenum steel tubes, assembled by automated welding to guarantee the highest levels of quality. Rigidity has been specially designed to guarantee outstanding handling. The excellent cohesion with the suspension 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. The frame of all SX models inherits the highly resistant lacquer coating (used on KTM Factory machines) and standard frame protectors. The rear buckle, made of lightweight aluminum, reinforces the stability of the rear shell and provides excellent support for the rider, despite its low weight.

swingarm

the one-piece, high-pressure-molded swingarm has been designed for maximum strength and minimum weight. It offers a wide range of rear-wheel adjustments, allowing you to reduce the wheelbase for greater manoeuvrability on narrow, winding tracks, or increase it for greater stability on fast sections. The chain measurement marks on the swingarm are visible from above, making adjustments 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 nipples have been redesigned to reduce the frequency with which spokes need to be re-tensioned. The wheels are fitted with latest-generation DUNLOP Geomax MX 3S tires, to maximize power transfer to the ground and enhance stability.

front suspension

all standard-size KTM SX models feature the ultra-light WP XACT AER fork. The arms of this 48 mm USD air fork have different functions: damping is on the right, air springing is on the left. The left fork arm 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 fork arm features a cartridge specially designed to meet the requirements of the single-arm design, and can be adjusted to suit track conditions or rider preference. To fine-tune each of these settings (compression from the top and rebound from the bottom), simply turn the new 30-notch knob above each fork arm.

rear suspension

the WP XACT DDC shock absorber, featured on all KTM SX models, has beenthe WP XACT DDC shock absorber, found on all KTM SX models, was developed with the frame and swingarm architecture in mind, as were the linkage system and the WP XACT AER fork. Beyond its purely functional aspect, this little jewel captivates with its meticulous attention to detail, and in particular its high-quality machined and anodized components. Fully adjustable for high-speed and low-speed compression, it can be specifically adapted to track conditions or rider preferences.

fork tees

all KTM SX models use high-quality CNC-machined fork crowns, a KTM trademark. To take account of the flexibility of the frame and fork, engineers have stiffened the upper fork crown (22 mm offset on all models). The front end works in perfect harmony with the frame, making the bike even more stable and agile. Two positions are possible for the handlebar trigger guard, with vibration-damping rubber. The hour meter, fitted as standard on the upper fork crown of all SX models, keeps track of hours spent in the saddle and indicates when it's time for maintenance.

brakes

state-of-the-art Brembo brakes are standard equipment on KTM motocross bikes. Combined with Wave brake discs renowned for their lightness, they deliver the stopping power expected by the most daring riders.

fuel tank

all KTM SX models feature an ultra-light polyethylene fuel tank. The shape of this tank has been designed to be more ergonomic, while retaining the same capacity (7 liters). The internally threaded fuel filler cap ensures easy, reliable closure.

air filter housing

the air filter housing on the 250 SX optimizes flow dynamics. Combined with the intake snorkels, it ensures maximum power delivery and excellent acceleration. In addition to the obvious performance gains, the 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.

ergonomics and comfort

the feeling of being at one with the bike depends essentially on the rider's ability to transfer body weight quickly and efficiently. Particular attention has been paid to the fairing and ergonomics of the bike to ensure optimum performance. To enable the rider to find a more natural riding position and maintain complete control of the bike, the position of the handlebars can be adjusted according to preference and conditions. As the rider interacts primarily with the saddle, footpegs and handlebars, these three contact points play a key role in balance and control. To stay one step ahead of the competition, a rider needs a machine that combines power and agility. The 250 SX 2020, like all models in the SX range, perfectly meets these requirements, and offers state-of-the-art ergonomics.

saddle

the saddle on all KTM SX models confirms the progress made in terms of dynamism and ergonomics. The saddle cover incorporates silicone strips to optimize grip and feel. A long screw inserted into the side of the saddle secures it more securely to the motorcycle, making it easier and safer to handle.

handlebars

all standard-size KTM SX models feature the same ultra-strong, profiled aluminum handlebars made by NEKEN. Two positions are possible for the handlebar trigger guard with shock absorbers. right: an ODI vulcanized handlebar grip available as standard; left: an ODI lock-on handlebar grip that's as comfortable as it is practical, thanks to its glue- and wire-free mounting system. The handlebars feature handlebar foam and handguards that are easy to fit and remove.

footrests

sophisticated "zero-dirt" footrests prevent the gear selector from getting dirty, even when riding in deep ruts.

styling and graphics

the 250 SX has become a veritable icon for 2-stroke motorcycle enthusiasts. Even if the characteristic sound of this engine invites nostalgia, it has undergone numerous evolutions over the years. KTM factory pilots collaborated with KTM R&D specialists and design agency Kiska GmbH on the fairing's development, with a single watchword in mind: to create perfect harmony between rider and machine, and to offer a motorcycle at the cutting edge of modernity. Particular attention has been paid to the points of contact, to ensure total freedom of movement for the rider and optimum control of the vehicle. The particular shape of the front and rear shells is a perfect example of the ingenuity of the design: it guarantees maximum stability for minimum weight.

software and electronics

the 250 SX boasts electronics to match its ambitions. Pure 2-stroke simplicity, the hour meter (available as standard) keeps track of hours spent in the saddle, while the tachometer (available as an option) helps you find the ideal rpm.

Information and images credits: KTM