Motorcycle specifications KTM250 SX 2019 A sultry moment

The KTM 250 SX is an excellent combination of weight and power, or performance and control. With its high-performance 2-stroke engine and innovative chassis, it's definitely one of the fastest 250 cm3 2-stroke bikes on the circuit. This racing beast is the ideal choice for speed enthusiasts who love the distinctive sound of 2-strokes.

engine

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

cylinder

the cylinder of the KTM 250 SX, with a bore of 66.4 mm, features a TVC valve-operated control spindle. The exhaust channel of the 2019 models has been machined to ensure more precise operation of the control spindle and increase overall performance levels. In addition, the engine's character can be changed quickly and easily thanks to the two springs provided, 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 now made of aluminum rather than steel, to dampen vibrations almost completely.

crankcases and covers

the use of a high-pressure die-casting process has resulted 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 KTM 250 SX features 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 KTM 250 SX is equipped with a MIKUNI TMX carburetor. The settings of this 38 mm flat-bottom carburetor have been adapted to the new air filter housing and exhaust structure, to ensure a more linear and better-dosed power delivery across the entire rev range.

contact

all 2-stroke models feature a new capacitor-discharge ignition control unit and advanced components designed to improve engine starting behavior. Ignition curves remain unchanged.

crankshaft

the 72 mm-stroke crankshaft guarantees superior torque and maximum power. Perfectly balanced, it is combined with a balancer shaft to minimize vibration. Ideally positioned for optimum mass centralization, it contributes to the bike's agility and roadholding.

cooling

to ensure smooth power delivery, it's essential to maintain optimum engine temperature. To this end, the KTM 250 SX features new radiators that are 12 mm lower than the 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 gives the engine a smoothness and liveliness that are hard to match. Its shape is also 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 new chassis of the KTM 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. For the 2019 model year, the engine has been raised by 1° in relation to the swingarm axis, to enhance handling and front-wheel grip. The improvements to the new chassis enhance the exhilarating handling of the KTM 250 SX.

frame

the chromium-molybdenum steel frame of the KTM 250 SX is completely new. It consists of hydroformed tubes assembled by automated welding, to guarantee the highest levels of quality and homogeneity. The frame's flexibility has been specially calculated to offer the best possible compromise between agility and comfort. The excellent cohesion with the suspension also guarantees excellent stability at high speeds. And with self-cleaning "zero-dirt" footrests that won't jam when returned to position, you remain in complete control, whatever the conditions. The engine of the KTM 250 SX has been raised by 1° in relation to the swingarm axis, to enhance handling and front-wheel grip. New aluminum dropouts have been added to lighten the bike. The frame of all 2019 SX models inherits the highly resistant powder coating (used on KTM Factory machines) and standard frame protectors. The rear buckle, made of lightweight aluminum, has been lengthened by 40 mm to improve rear shell stability.

swingarm

the KTM 250 SX features an optimized one-piece swingarm with 5 mm extra clearance in the axle housing. This allows the wheelbase to be adjusted to suit the conditions, for better negotiation of hairpins on motocross tracks, or enhanced straight-line stability when the pace picks up. Obtained by high-pressure molding, the one-piece swingarm offers maximum strength for minimum weight. Chain measurement markings on the swingarm are clearly visible from above, making adjustments a breeze.

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.

rear suspension

the DDC shock absorber, present on all SX models, was developed with the new frame and swingarm architecture in mind, as were the linkage system and the AER 48 front 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. The settings and main piston inside the shock absorber have been redesigned to improve damping characteristics in conjunction with the new front-end setting. Fully adjustable for high-speed and low-speed compression, it can be specifically adapted to track conditions or rider preferences.

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 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.

air filter housing

the air filter housing of the KTM 250 SX 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. These handlebars offer the level of control needed to stay in control of the track, and excellent grip to support the 2-stroke's impressive power.

software and electronics

the new KTM 250 SX boasts electronics to match its ambitions. The hour meter (available as standard) counts the hours spent in the saddle, while the tachometer (available as an option) helps you find the ideal rpm.

Information and images credits: KTM