Motorcycle specifications KTM125 SX 2018 First attack

For many years now, the KTM 125 SX has been in insolent health on the market. And given the performance it offers, it's got plenty of years ahead of it. A real featherweight in its class, this bike boasts a compact chassis and a high-performance 125 cm3 2-stroke engine that's just begging to be used. It's a bike that's sure to wreak havoc.

eNGINE

the latest engine for the KTM 125 SX is the most powerful and competitive unit in its class, and proves that two-stroke technology is not just for bikes.shows that 2-stroke technology has a bright future ahead of it, thanks to its excellent power-to-weight ratio, low cost and simplicity. This 125 cm3 engine, the fruit of KTM's technical expertise, incorporates the latest technological innovations on the market. Despite its compact structure and weight of just 17.2 kg, it delivers great power across the entire rev range. The rider has everything he needs to start collecting trophies.

cYLINDER

this ultra-compact cylinder, with a bore of 54 mm, features state-of-the-art exhaust control and a sophisticated mechanism for the side support exhaust channels. 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.

eNGINE HOUSING

kTM engineers have designed ultra-light molded crankcases. They have also raised the crankshaft position to bring it closer to the center of gravity, thus centralizing mass and enhancing rideability.

eNGINE

the KTM 125 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.

gEARBOX

another interesting innovation designed specifically for the 2-stroke engine is a robust 6-speed gearbox perfectly adapted to the 125's range of use. Engineers have even reworked the 3rd, 4th and 5th gears to improve reliability. The engine's weight reduction and shrinking were made possible by the use of ultra-modern production technologies. As safety is also an essential parameter, the selector adopts a "zero-dirt" design that prevents the lever joint from jamming due to soiling.

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.

eXHAUST

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

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.

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 chromium-molybdenum steel frame is a model of lightness, flexibility and maneuverability, offering excellent stability and devilishly precise cornering. Thanks to its high torsional stiffness and low longitudinal rigidity, this frame absorbs the energy generated by the front and rear suspensions when jumping or going over a bump. The ride is more comfortable and less tiring. The brackets that link the cylinder head to the frame are now made of lightweight aluminum. Mounted laterally, they help to limit vibration levels and refine the bike's trajectory when cornering. 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.

fOOTREST

sophisticated "zero-dirt" footrests prevent the pivot from fouling, even when riding in deep ruts. Riding position not high enough? No problem! The footrest mounting system on AM 2018 KTM EXC models has been raised by 6 mm compared to the SX versions.

gUIDON

when it comes to handlebars, KTM engineers have always known which way to go. Profiled and made of high-strength aluminum, this handlebar is 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.

oSCILLANT ARM

in addition to saving weight, 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.

fUEL TANK

the ultra-light polyethylene fuel tank has a capacity of 7 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 management of internal airflow 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 benefits from a new setting that inspires complete confidence and optimized damping characteristics that go hand in hand with the front-end setting. And to show that you've got good taste in suspension, the shock absorber comes in WP's trademark gleaming colors.

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 incorporates 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 brake 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