TEMECULA, CALIFORNIA (KTM HQ) – “When we develop our motorcycles there are some key things we strive for; aim higher, ride faster, do better and give more. It’s about creating a technically advanced, phenomenally designed piece of machinery that allows a rider to showcase their skills, reach their ambitions and be the very best they can be. This year we welcome a new generation of KTM SX. A superior range of class-leading motocross bikes that boast low-weight, sublime agility and strong, usable power for every bike that sets the benchmark in each class.”
KTM 250SX-F – The KTM 250 SX-F has been best performing bike in its class and is set to continue its dominance with more innovative changes to the engine, intake, exhaust system, and the EFI mapping. Not only is it the lightest bike in its class, but it also faster than ever before, making it the best choice for both amateurs and professionals.
E-STARTER – Like all KTM 4-strokes, the KTM 250 SX-F is equipped with an electric starter – an invaluable bene t when the going gets tough. A strong starter motor from Mitsuba and a reliable starter drive ensure that the engine starts every time.
BALANCER SHAFT – To minimize vibration, the engine of the KTM 250 SX-F is tted with a multifunctional balancer shaft, which also drives the coolant pump and the timing chain.
CLUTCH – The KTM 250 SX-F is equipped with a newly developed DS (diaphragm steel) clutch with a one-piece outer clutch hub and a primary gear made of high strength billet steel. This guarantees unbeatable reliability and, due to its compact, rivetless construction, results in a compact engine design. Extremely heat-resistant steel clutch plates ensure smooth disengagement of the clutch. Fitted with a diaphragm spring, very little force is required to operate the clutch. The Brembo hydraulic system also ensures easy and precise action.
CYLINDER & PISTON – The short-stroke cylinder has a 78 mm bore and contains
a weight-reduced, extremely rigid, forged bridged box-type piston produced by CP. The piston crown geometry has been adapted perfectly to the combustion chamber and the high compression ratio of 14.4:1.
ENGINE MANAGEMENT SYSTEM – The state-of-the-art Keihin engine management system with electronic fuel injection and 44 mm throttle body features an innovative injector positioning for enhanced engine response, a new throttle cable mount for smoother cable routing and a redesigned seal for the MAP (manifold air pressure) sensor to make the system even more reliable. There are also separate systems available for cold start and idle adjustments. The control unit features completely new mapping adapted to the new exhaust system and cylinder head and now incorporates split injection in specic areas of the map, providing improved atomization and engine response. The ignition timing, the ignition advancement timing by throttle positon and the amount of fuel (injection duration), including acceleration enrichment and injection timing, were also changed to t to the new power pack con guration. The control unit also regulates the traction and launch control functions and provides different maps for specic power curves depending on which gear is currently engaged.
CRANKSHAFT – The KTM 250 SX-F crankshaft features a short connecting rod with a plain big (bottom) end bearing with two force- tted shells running directly on the crank pin. This design is required for the extremely high revs and the unrivaled maximum power output of the 250cc engine. At the same time, it extends the life of the engine and results in long crankshaft service intervals.
ENGINE – The compact KTM 350 SX-F engine weighs a mere 26.6 kg / 58.6 lb and has updates to the exhaust system, air lter box, velocity stack and engine management system, resulting in an unbeatable power curve throughout the entire rpm range (to its maximum of 13,400 rpm) and improved bottom end torque.VIt also features a new clutch, optimized transmission and an upgraded and lighter DOHC cylinder head. This is all rounded off with state-of-the-art electronic fuel injection and an E-starter.
SUBFRAME – To improve the stability of the rear fender, the subframe is now 40 mm longer and consists of extremely lightweight and highly stable aluminum sections weighing less than 900g.
SWING ARM – For 2019, all KTM SX-F models feature an upgraded cast aluminum swingarm with a longer chain adjustment slot for the rear axle. The rear wheel can now be positioned further back by as much as 5 mm, enabling the rider to increase straight-line stability on fast tracks. As a result of the one-piece casting process, the swingarm offers improved ex behaviors while minimizing weight.
FRAME – All KTM SX-F models feature new, lightweight and high-tech frames made of chromium molybdenum steel sections that include hydro-formed elements constructed with state-of-the-art robotic welds. They have the same proven geometries as before but, due to a redesign in several key areas, they feature an optimized stiffness (longitudinal + 2%, torsional + 10%) compared to previous versions, providing better feedback to the rider, more precise handling and improved stability. The lateral engine head stays between the cylinder head and the frame are now made of aluminum. This results in reduced vibration levels, precise cornering and weight savings. Newly designed lateral frame guards featuring structured surfaces improve grip, while the frame guard on the exhaust side also provides heat protection. Three new brackets on the frame of the 4-stroke models make it possible to add an optional composite skid plate that will be included in the KTM PowerParts product line.
E-STARTER – All SX-F engines are tted with an E-starter – a long-time KTM feature – which is now powered by a new, more powerful and super-lightweight 2 Ah lithium ion battery. This guarantees reliable starting, particularly at low temperatures, and contributes to the bike’s low weight. Redesigned packaging of the voltage regulator and condenser means that the electrical components are now located in a compact area below the seat, increasing the reliability of the entire system.
SHOCK OBSORBER – The WP shock absorber has been developed with the entire frame and swingarm architecture in mind, including the linkage and the WP AER 48 front fork. An upgraded main piston and new settings have resulted in optimized damping characteristics. Further, the shock absorber is fully adjustable, including rebound and high/low-speed compression damping and features machined and black anodized components and the WP color scheme.
FORK – Developed by WP in close collaboration with KTM, the revolutionary, super-lightweight WP AER 48 upside-down fork with a 48 mm inner fork tube diameter and an air spring unit is fitted to all SX models. It is a split fork design with damping on the right and the air spring on the left. The air leg is updated with a new spacer which reduces the air volume in the negative chamber by 50%. This is to improve the “breakaway” feel in the fork in the initial part of the stroke. It incorporates a single air valve, making it easy to adjust the air suspension for different riders or conditions. No special tools are required; just use the supplied air pump. Compression damping adjustments can be made by simply twisting a dial on the top of the right fork leg, while rebound adjustments are made at the bottom (30 clicks are available for each). KTM has provided new settings for both the damping characteristics and responsiveness of the WP AER 48 fork for model year 2019, the damping leg has valving re nements with a two-stage base valve setting, a re ned mid valve setting and a more progressive rebound setting.
MAP SELECTION – All 4-stroke models are equipped with a multifunctional handlebar-mounted map select switch, which includes a traction control function, launch control function and additional power curve functions. With its new setting, the traction control function provides even more traction when accelerating, particularly on a wet or muddy track. It is activated on the go via the map select switch. When idling, the rider can also activate the launch control function. This reduces maximum revs during initial throttle activation and now automatically engages the traction control function to deliver optimized starts. The EFI indicator lights mounted on the upper triple clamp enable the rider to see when the function is activated. The map switch allows the rider to select between the standard con gyration and a more aggressive power curve.
BODY WORK – From the KTM R&D team to the Factory Racing team riders, a wide variety of experience and knowledge was taken into consideration in designing the bodywork of the new SX generation. The objective was to achieve complete harmony between the rider and the bike down to the nest detail. The results are all new plastics that provide perfect ergonomics and contact points for the rider, maximum freedom of movement and improved handling. In addition, the I-beam design for the front and rear fenders guarantees maximum stability at lowest possible weight.
COOLING SYSTEM – All models are tted with newly developed radiators, which are now mounted 12 mm lower, providing a lower center of gravity and improved ergonomics. With a ow-optimized cooling circuit and optimizing the air ow using computational uid dynamics (CFD) modelling, KTM’s engineers have been able to increase the ef ciency of the radiators. Due primarily to a modi ed delta distributor integrated in the frame triangle, which features a center tube with a 4 mm larger diameter, the cross section has been increased by 57%. This ensures that the coolant ows more ef ciently from the cylinder head to the radiators. Newly designed radiator covers at the front provide increased protection in the event of a crash.
WEIGHT – One aim of the KTM engineers during development of the new SX-F models was a further reduction in weight compared to the previous generation. The result is that the current SX-F models have again set the benchmark for the lightest bikes on the market (218.3 lb for 250 SX-F and 219.4 lb for 350 SX-F).
SEAT – A newly shaped seat provides improved ergonomics and better seat comfort. Due to newly developed silicone strips, the seat cover provides better feel and grip. The xation of the seat with one long, lateral screw enables easy removal and installation.
HANDLEBAR – All SX-F models are equipped with a tapered handlebar made of high-strength aluminum alloy from NEKEN. A handlebar mount with rubber inserts allows the handlebar to be xed in two different positions. An ODI vulcanized grip is tted on the right-hand side, and an ODI lock-on grip is tted on the left-hand side. An upgraded slide pad featuring a newly designed cover is xed securely on the handlebar.
WHEELS – KTM wheels feature lightweight, CNC milled hubs and high-end Excel rims to combine minimum weight and maximum stability. For model year 2019, KTM has upgraded the aluminum spoke nipples and subsequently reduced the amount of maintenance required. The wheels are tied with Dunlop Geomax MX-3S tires.
BRAKES – High-tech Brembo brakes have always been standard equipment on KTM off-road bikes, and are combined with lightweight Wave discs.
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