Motorcycle specifications KTM125 SX 2019 Argumentative introduction

The new KTM 125 SX is a delight to ride. It is one of the most compact and lightest of the standard-sized motorcycles. The combination of a new, lighter chassis and the most powerful 125 cm3 2-stroke engine opens up new horizons for the most impetuous of young riders. More lively than ever, this 2-stroke allows you to build up your trophy collection before entering the profession.

engine

the latest version of the KTM 125 SX engine once again proves to be the most powerful and competitive unit in its class.its excellent power-to-weight ratio, low cost and simplicity prove that 2-stroke technology has a bright future at KTM. This compact, durable 17.2 kg engine, the fruit of KTM's technical expertise, delivers great power across the entire rpm range. Precise and powerful, this engine delivers excellent lap times and better results.

cylinder

the cylinder, with its 54 mm bore, has been the subject of several improvements within the 125 cm³ engine. It features an optimized control spindle and a sophisticated mechanism for the side support exhaust channels. The new configuration of the exhaust channels contributes to increasing the engine's performance level. The upper contour of these components has even been machined to ensure ultra-precise timing. Combined with the two-piece cylinder head, this reworked cylinder is responsible for a clear increase in power across the entire rev range of the KTM 125 SX.

crankcases and covers

the use of a high-pressure die-casting process produces thin walls while preserving the strength and durability of the crankcase. The crankcase design enabled KTM engineers to raise the position of the crankshaft closer to the center of gravity, thus centralizing mass and enhancing rideability. The lightness of the engine block owes much to the extremely compact shape of the crankcase. On 2019 models, the intermediate starter pinion seat has also been strengthened to enhance reliability. Thanks to the new clutch arrangement, the clutch housing is now positioned lower, saving 10 mm on the width of the engine block

gearbox

the KTM 125 SX is now equipped with a new, more robust 6-speed gearbox. The transmission ratios of the previous version have been retained, but the sprockets have all been improved and reinforced. Another highlight of the transmission on the KTM 125 SX is the "zero dirt" design of the shifter. Designed on the same principle as the footrest, it prevents the accumulation of dust and enables the gearbox to remain operational in all conditions.

carburetor

the KTM 125 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 to ensure a more linear and better-dosed power delivery across the entire rpm range.

contact

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

cooling

to ensure smooth power delivery, it's essential to maintain optimum engine temperature. To this end, the KTM 150 SX features new radiators that are 12 mm lower than those of its 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 2019 version of the KTM 125 SX relies on a new high-tech steel frame capable not only of reacting precisely to every rider action, but also of providing excellent feedback. The frame's flexibility has been specially designed to absorb the heaviest shocks and enhance the bike's agility and stability at high speeds. All in all, this new chassis allows the rider to remain in complete control of his riding at all times.

frame

the KTM 125 SX's completely redesigned frame and rear end encourage the aggressive riding styles that are de rigueur in the 125cc class. As with the rest of the SX range, the chromium-molybdenum steel frame is made of hydroformed tubes assembled by automated welding, to guarantee the highest level of quality. Rigidity has been specially designed to enhance handling. The excellent cohesion with the suspension offers the perfect compromise between agility and high-speed stability. 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 2019 SX models inherits the highly resistant powder coating (used on KTM Factory machines) and standard frame protectors. The new 40 mm longer rear buckle is made of lightweight aluminum to improve rear shell stability.

swingarm

the KTM 125 SX's new one-piece swingarm, produced by high-pressure die-casting, has been designed for maximum strength, while keeping weight to an absolute minimum. The new shape of the axle housing now offers an additional 5 mm of play, allowing the wheel to be set back to improve straight-line stability on the most demanding tracks. The chain measurement marks on the swingarm are visible from above, making adjustment 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 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 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.

brakes

the latest Brembo brakes are standard equipment on KTM motocross bikes. Combined with Wave brake discs renowned for their light weight, 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 125 SX has been completely redesigned to optimize flow dynamics and ensure exceptional power delivery and acceleration. In addition to the obvious performance gains, the new design also serves to better protect 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. on the right: a vulcanized ODI handle available as standard; on the left: an ODI lock-on handle 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 allow you to adopt a truly aggressive riding style, as is customary on a 125 cm3.

software and electronics

the new KTM 125 SX is equipped with 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