Motorcycle specifications KTM450 SX-F 2019 Filling in the bumps

This is cross-country riding at its most muscular. The KTM 450 SX-F has proven itself over the years in the world's leading championships. The 2019 vintage takes performance and handling to new heights. It features a new, extremely compact single overhead camshaft cylinder head and the latest electronic fuel injection system. Powered by a 63 HP engine of rare efficiency, this 450 cm3 is the fastest motocrosser ever built by KTM.

engine

the 450 cm3 engine is the most competitive in the KTM motocross range. Considerably reworked for the 2019 model, it has undergone yet another slimming and weight reduction. It features a new, extremely compact single overhead camshaft cylinder head and the latest electronic fuel injection system. As a result, the impressive 63 HP are more efficiently distributed across the rev range. Even with the highly beneficial electric starter, this model remains the lightest 450 cm3 on the motocross market.

cylinder head

the centerpiece of the SOHC (single overhead camshaft) engine, the 450 SX-F's new cylinder head is much more compact. It has been lightened by 500 grams and lowered by 15 mm. These modifications have resulted in greater mass centralization and new levels of driveability. The optimized surface of the new overhead camshaft (which is now closer to the center of gravity) and the shorter valve-opening time have improved the engine's responsiveness. The four ultra-light titanium valves (intake: 40 mm, exhaust: 33 mm) are operated by ultra-rigid rockers. The rockers are DLC-coated on the intake side to enable extremely high engine speeds of up to 11,500 rpm. New low-friction chain guides have also been designed to cope with the engine's extra power. The new overhead shaft configuration ensures even greater power delivery to leave the competition in its wake.

crankshaft

the 450 SX-F's crankshaft is ideally positioned, close to the center of gravity, to better centralize mass. It uses a short connecting rod, making the engine even more compact and responsive. The whole unit is perfectly balanced. Inertia forces are ideally balanced to enhance traction and driving pleasure. The connecting-rod bearing features two half-bearings force-fitted directly onto the crankshaft crankpin, and the oil supply is provided by the engine's pressure lubrication system. This design extends engine life and extends crankshaft service intervals, saving the customer time, effort and money.

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 transmission of the 2019 version of the 450 SX-F has been redesigned to enhance its durability. However, it was not deemed necessary to change the gear ratios, which are perfectly suited to the power delivered by the large-displacement engine. All 4-stroke engines are equipped with an engaged-gear sensor that allows the engine characteristics to be adapted to each gear, depending on the engine load. The "zero dirt" design of the selector prevents the accumulation of mud or dust in the joint.

engine management

the Keihin engine management system with electronic fuel injection features a new 44 mm injector body. The unique position of the injector ensures excellent atomization of the fuel and air entering the combustion chamber. The engine is even more lively and generous when the throttle is opened. For added convenience, independent adjustment mechanisms have been provided for cold start and idle. The MAP sensor (absolute pressure sensor) has been made even more watertight, making the system even more reliable. Modifications to the throttle cable have simplified cable routing and made them more accessible. The control unit (ECU) on the 2019 models features new mappings adapted to the new exhaust and cylinder head design, with the aim of better managing traction control and starting control. To deliver maximum power, it adapts the engine's characteristics at each speed, according to the data communicated by the engaged gear sensor.

cylinder and piston

the 95 mm-bore cylinder houses a lightweight piston with a high-quality "box-in-box" structure, helping to reduce vibration and enhance overall engine performance. The compression ratio (12.75:1) and reduced oscillating weights result in an engine that is both powerful and extremely responsive.

balancer shaft

the side-mounted balancer shaft performs a dual function, perfectly balancing the oscillating masses and simultaneously driving the water pump. Free from annoying vibrations, the bike offers unrivalled riding smoothness, even at high revs.

clutch

the 450 SX-F 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.

electric starter

the electric starter, available as standard on the KTM 450 SX-F, uses a proven drive system and Mitsuba's robust electric motor. This system has proven its worth time and again: its rock-solid reliability saves precious time and effort at crucial moments.

handlebar-mounted map selector

all Katoche 4-stroke SX models feature a handlebar-mounted map selector.all Katoche SX models feature a handlebar-mounted map selector for traction and start control, and for switching between power curves (Standard <-> Advanced). Traction control is a unique function with a new setting on 2019 models. It ensures more efficient traction and better control of the bike during acceleration phases, especially on demanding tracks. This function can be activated, even at full throttle, using the map selector on the handlebars. When the engine is at idle, simply press both switches simultaneously to activate the start control as well, for a quicker jump off the grid. Thanks to a new set-up, start control can now take advantage of traction control to limit wheel slip and gain traction. In addition to the standard engine modes, the map selector gives access to other engine modes for maximum racing options.

cooling

to ensure smooth power delivery, it's essential to maintain optimum engine temperature. To this end, the 450 SX-F 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, fitted to all 4-stroke models, gives the engine a smoothness and liveliness that are hard to match. It features a new exhaust manifold (specific to the model) and a small additional chamber, i.e. an advanced resonator called FDH (Flow Design Header). The muffler benefits from a new aluminum casing and a new nozzle. The interior of the silencer has also been reworked. The new structure allows the exhaust to be disassembled without having to remove the shock absorber, and facilitates access to the latter. Another ergonomic advantage is the slimmer silhouette of the motorcycle, while respecting regulatory noise emission levels.

chassis

the 450 SX delivers titanic torque and requires a frame of great strength to support the engine's prodigious power. The 2019 model inherits a new high-tech steel frame designed to increase the bike's power-to-weight ratio, without compromising its strength and durability. Its great flexibility means it can take the biggest knocks without flinching, and enhances the bike's agility and stability at high speeds. The chassis has also benefited from a number of innovations, such as "zero dirt" footrests and optional composite skid plate mounting brackets.

frame

the new frame of the KTM 450 SX-F is better able to withstand the forces generated by the super-powerful engine. As with the rest of the 2019 SX range, it is made of hydroformed chromium-molybdenum steel tubes, assembled by automated welding to guarantee the highest levels of quality and strength. Its greater rigidity contributes to the bike's excellent handling. The excellent cohesion with the suspension also offers the perfect compromise between comfort and stability at high speeds. The "zero dirt" footrests benefit from a self-cleaning system that's as simple as it is effective. Since there's no risk of the footrests jamming when they're brought back into position, you're in complete control, whatever the conditions. The frames of all 2019 SX-F 4-stroke models feature three new brackets to facilitate fitting of an optional composite protection shoe (offered in the KTM PowerParts range of accessories). The frame of all 2019 SX models inherits a highly resistant powder-coating (as on KTM Factory machines) and standard frame protectors. The lightweight aluminum rear buckle has been lengthened by 40 mm to improve rear hull stability and promote mobility on the saddle.

swingarm

the 450 SX-F benefits from a new monoblock swingarm, obtained by high-pressure die-casting. This gives it the strength needed to withstand the harsh conditions of motocross and the brutal torque of a 450 cm3. The additional 5 mm of play in the axle housing allows the wheelbase to be adjusted to suit the conditions. All this while keeping weight to an absolute minimum. 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.

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

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

air filter housing

the air filter housing of the KTM 450 SX-F 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.

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. The characteristics of the handlebars and grips have been designed to ensure excellent grip and total control of the machine.

software and electronics

although the 450 SX-F's engine develops a demonic 63 HP, it remains entirely controllable. In addition to the mechanical elements designed to channel this energy, the rider can rely on an electronic package to dose it with maximum precision. The cartography selector on the handlebars can be used to adjust traction and start control, and to select different power curves. Many hours of work went into optimizing power and torque. Transferring this energy to the ground, however, requires state-of-the-art electronics. Operated at the touch of a button, the tried-and-tested electric starter is ready for any motocross eventuality.

Information and images credits: KTM