Motorcycle specifications KTM250 SX 2018 Punch and lightness

In the motocross world, the KTM 250 SX boasts one of the best power-to-weight ratios in its class. Confident in its strength, it's even ready to take on more complex 4-stroke bikes. With the punch needed to excel on all types of track and terrain, and an uncommon sense of placement thanks to its ultra-light chassis, the jewel of KTM's R&D teams and motorsports specialists is destined to become the future king of the discipline.

eNGINE

the KTM 250 SX's 2-stroke engine has long enjoyed a reputation as the most powerful unit in its class, confirming the enormous potential of KTM's 2-stroke engines. Inexpensive, these engines shine for their simplicity. And what about their power-to-weight ratio? It's simply mind-boggling. The KTM 250 SX engine has benefited from numerous improvements: improved mass centralization, TVC exhaust valve-operated control shaft, vibration-damping balancer shaft, 5-speed gearbox and hydraulic DDS clutch. Lightning-quick, this compact engine has everything to dazzle performance-seeking competitors and seduce budget-conscious, maintenance-conscious riders. Let yourself be stunned by the gentle roar of a 2-stroke engine.

cYLINDER

this ultra-compact cylinder, with a bore of 66.4 mm, features an avant-garde control spindle and a sophisticated mechanism for the exhaust channels in the side mount. Combined with the two-piece cylinder head, this design is responsible for a clear increase in power across the range. The layout of the water jackets inside the cylinder and cylinder head ensures efficient heat dissipation under high engine loads.

mOTOR HOUSES

moulded crankcases have been designed to free up spaceto make room for a balancer shaft, so that you can speed down the road in complete relaxation. 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.

bALANCER SHAFT

numb hands and feet are not inevitable. The engine's design has made it possible to use a side-mounted balancer shaft to help minimize vibrations. This obviously has a beneficial effect on driving pleasure.

gEARBOX

the robust gearbox offers 5 speeds perfectly adapted to the 250's range of use. The "zero dirt" design of the selector avoids clogging and jamming of the lever joint for safer gearshifts.

eMBRAYAGE

the KTM 250 SX uses a DDS (Damped Diaphragm Steel) clutch developed by KTM. a sturdy steel clutch housing, heat-resistant clutch plates and new nitrate-treated steel liners that are less prone to wear. A special feature of this clever design is the use of a diaphragm spring instead of the usual coil springs, giving the clutch greater flexibility. The diaphragm spring also leaves plenty of room for a damping system integrated into the clutch hub, to enhance traction and durability. The clutch is activated by a hydraulic system manufactured by Brembo, which plays an essential role in the clutch's progressiveness and flexibility.

eXHAUST SYSTEM

the resonator has been carefully tuned to deliver even more power and torque. This engine is a marvel of explosiveness and solidity.

iGNITION

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.

cARBURER

the KTM 250 SX is equipped with a MIKUNI TMX carburetor. This 38 mm flat-barrel carburetor offers a clear improvement in power delivery right up to the rev limiter. Thanks to a new distributor tube, the carburetor has been rotated by 7° to reduce the risk of fuel overflow. It is also less sensitive to changes in altitude and temperature.

lIGHT WEIGHT

year after year, KTM engineers strive to make their bikes lighter. The result is clear: the 2018 KTM SX models are among the lightest and sleekest motocross bikes on the market.

fOOTREST

sophisticated "zero dirt" footrests prevent the gear selector from getting dirty, even when going through deep ruts. Driving position not high enough? No problem! The footrest mounting system on AM 2018 EXC models has been raised by 6 mm compared to the SX versions.

aIR FILTER HOUSING

the air filter housing has been designed to better protect the air filter from clogging and ensure optimum air flow. The cage housing the extra-large Twin Air air filter is totally rigid, helping to hold the system in place. The design is so simple that you could replace the filter even with your face covered in mud. And you don't need any tools. And in a matter of seconds.

fRAME

the high-tech chrome-moly steel frame, a model of lightness, flexibility andthe high-tech chromium-molybdenum steel frame is a model of lightness, flexibility and manoeuvrability, offering excellent stability and diabolical precision when cornering. Thanks to its high torsional stiffness and low longitudinal rigidity, this frame better absorbs the energy generated by the front and rear suspensions when jumping or negotiating a bump. The ride is more comfortable and less tiring. The dropouts that link the cylinder head to the frame are as light as ever. Side-mounted, they also help to limit vibration levels and refine the bike's trajectory in bends. The engineers can be proud of their work, as the frame is now one kilo lighter than the lightest competing frame on the market today. Every effort has also been made to facilitate maintenance and free up space for the fuel tank and other components. The ultra-light rear section, made of stable aluminum profiles, weighs in at less than 900 grams.

oSCILLANT ARM

In addition to weight savings, cast aluminum is ideal for bending. The one-piece molding process eliminates the imperfections inherent in welding, guaranteeing a more homogeneous, but also more meticulous, manufacturing quality.

gUIDON

when it comes to handlebars, KTM engineers have always known which way to go. Profiled and made of high-strength aluminum, these handlebars are no exception to the rule. It features rubber shock-absorbing pads and can be adjusted to two positions. The ODI handlebar is easy to change when needed, thanks to its glueless, wire-free mounting system.

fUEL TANK

the ultra-light polyethylene fuel tank has a capacity of 7.0 liters. The internally threaded fuel cap ensures easy, reliable closure.

wHEELS

featuring ultra-light CNC-machined hubs and top-of-the-range Excel rims, the wheels guarantee maximum stability despite limited unsprung weight. They are fitted with the latest-generation Dunlop Geomax MX 3S tires.

cOOLING SYSTEM

kTM's proven integrated cooling system circulates coolant from the cylinder head via the frame wishbone to the aluminum radiators supplied by WP. Its incredible efficiency is due to improved internal airflow management and advances in ventilation thanks to CFD (Computational Fluid Dynamics) calculations. The new radiator protections offer the advantage of better heat dissipation. This is all the more true in the presence of mud. Integrated into the front spoilers, these radiator guards are particularly useful in the event of an impact.

bODYWORK

all KTM factory riders collaborated on the bike's design with KTM R&D specialists and the Kiska design agency, with a single watchword: to create perfect harmony between rider and machine. Particular attention was paid to ergonomics and contact points to enhance freedom of movement on the SX. The special shape of the front and rear mudguards guarantees maximum stability and minimum weight, thanks to a well-thought-out structure and assembly. Best of all, they stay clean longer.

gRAPHICS

custom deco kit, Factory orange frame: every detail counts, because in this discipline, there's nothing more beautiful than a car that stands out from the crowd.

dAMPER

the WP shock absorber was developed with the frame and swingarm architecture in mind, as were the linkage system and the WP AER 48 fork. With its various machined and black-anodized components, this ultra-sophisticated shock absorber makes a strong impression compared to less well finished competing products. It features a new, confidence-inspiring tuning and optimized damping characteristics that go hand in hand with the front-end setting. The shock absorber's gleaming colors are typical of the WP brand.

fORK

another interesting new feature on this bike: the WP AER 48 inverted fork with air spring and separate damping circuits, developed by WP in close collaboration with KTM. The damping functions are on the right, the air spring on the left. The left fork arm features a double-chamber air cartridge system to prevent any loss of pressure. Should the outer seal leak, the pressure exerted inside the inner cartridge will hold the bike in position. The air spring is easily adjusted to the rider's weight using a single valve. No special tools are required: the air fork pump supplied as standard will do the trick. The right-hand fork leg features a cartridge specially designed to adapt to the type of damping required. Simply turn the 30-notch knob to the desired position (compression up and rebound down) to select the appropriate setting according to track conditions and rider preference. More comfortable and responsive than ever, this fork (with revised damping characteristics) is just waiting to be put through its paces.

fORK TIPS

high-quality CNC-machined fork crowns, which ensure ultra-precise front-end behavior, have been a KTM trademark for years. Two positions are possible for the handlebar trigger guard with shock absorbers. The hour meter tells you when it's time for a service.

bRAKES

these little jewels of technology are combined with Wave discs renowned for their lightness. More responsive, more efficient and more powerful than ever, Brembo brakes will cope with any situation.

Information and images: KTM