KTM’s new 2019 motocross range of the 2-stroke KTM 125 SX, KTM 150 SX and KTM 250 SX, comprised with the 4-stroke KTM 250 SX-F, KTM 350 SX-F and KTM 450 SX-F powerhouse have improved engines to provide more efficient performance. Taking a brief look at the new generation’s benefits and we can see a new high-tech chassis that provides improved stiffness, and a longer subframe for improved rear fender stability, whilst new bodywork with optimized ergonomics offer enhanced contact points and better seat comfort. Not only that, the radiators and cooling system have been re-designed for more efficient cooling, whilst revised WP suspension settings ensure riders enjoy more stability and better cornering, which is especially required in the heat of the battle.
KTM is proud of its newly designed exhaust systems for the SX range that contribute to a more efficient power delivery and upgraded performance, while new graphics and colors give the bike a totally new look. This is all in addition to the already premium components such as Brembo brakes, E-starter on 4-stroke machines, No-Dirt footpegs, a map select switch with integrated traction control, launch control and more that’s fitted as standard to the KTM SX range. These new machines are truly for dirtbike lovers who require the very best and with 60% new parts, R&D engineers in Mattighofen, Austria, and California, USA, have re-set the benchmark once again by producing battle-ready machines of the highest quality.
Winning is the ultimate ambition, but repeat success and staying at the top requires a special mentality. Investment back into R&D has been KTM’s strong point to achieve the many accolades over the years and advancements in technology in a short space of time, but it’s the desire to continue its outstanding battle domination in offroad racing that remains a major factor in the development process. This is not just about factory riders pushing the limits on the track and training to unbearable lengths off the circuit, but the push from within the very core of the company where everyone operates with the same united attitude. With another new SX generation arriving for model year 2019 that incorporates a huge re-design, the commonly heard saying ’after the race is before the race’ could not be any more apparent.
A world first was presented last year in the enduro sector with the serial production 2-stroke fuel injection offroad competition machines – the KTM EXC TPI models, and the boundaries are constantly pushed both sides of the Atlantic to continue being at the forefront of innovation. These lightweight motocrossers are READY TO RACE out of the crate, and remain the absolute benchmark in each class – you only need to look at the success last season with a double FIM Motocross World Championship win that reiterates that the KTM SX model year 2019 truly is the sharpest weapon.
Let’s take a look at what’s new:
All KTM SX models benefit in model year 2019 from new, lightweight high-tech frames made of chromium molybdenum steel sections that include hydro-formed elements welded together by state-of-the-art robots. For model year 2019 the new frames feature an upgraded design in specific areas for improved stiffness while keeping the same geometry compared with the predecessor versions. As a result, the
rider enjoys first-class feedback, playful handling and optimized stability. The lateral engine head stays between the cylinder head and the frame for all models, including KTM 250 SX models, 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 is included in the KTM PowerParts program. The engineers have also raised the engine of the KTM 250 SX around the swingarm pivot by 1° to improve handling and increase front wheel grip.
For the new model year, KTM has provided all SX models with 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. This enables the rider to increase straight-line stability on fast tracks. As a result of the one-piece casting process, the extremely lightweight swingarm boasts opti- mized bending stiffness and offers unlimited possibilities in terms of its design.
AIR FILTER BOX
The air filter box has been completely redesigned to optimize
the airflow to the engine, which subsequently improves both performance and throttle response. In addition, the new design provides maximum protection for the air filter against dirt and grime and, in combination with new intake snorkels (with the exception of the KTM 125 SX and KTM 150 SX models), results in improved engine performance. The large Twin Air filter is mounted in a stiff cage. This has the advantage of allowing both the filter and the cage to be replaced in just a few seconds without the need for tools, and correct assembly is also simplified – a typical feature of KTM motorcycles.
CHASSIS, BATTERY & WIRING HARNESS
All SX-F engines are fitted with an E-starter – a long-time KTM feature
and a distinct advantage in motocross racing events. For model year
2019, the bikes get a new, more powerful and super lightweight 2 Ah lithium ion starter 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 and increase the reliability of the entire system.
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 900 g.
KTM has invested substantial resources in the development of new standard exhaust systems, which are a major factor in terms of improving the power delivery and performance of the new bikes. They have a slim design and it goes without saying that they comply with FIM sound regulations. All 4-strokes are equipped with a new, model-specific header incorporating an advanced design resonator system in the form
of a small flow design header (FDH) chamber integrated into the pipe. This results in a system that has been thinned out and coaxes more performance out of the engine, besides being an effective means of reducing noise.
The 2-strokes also feature an upgraded header developed for model year 2019 using an innovative 3D stamping process, which also increases engine performance. The slimmer pipe increases the ground clearance of the KTM 250 SX and the new shape is more resistant to deformation. It also makes higher revving possible and thus gives the KTM 250 SX a much livelier performance.
All models are equipped with modified silencers designed specifically for the individual model.
The plastic collars used for the 2-strokes will now be replaced by lightweight metal brackets welded onto the aluminum sleeve. In addition, a new perforated core is combined with a new and lighter packing material, which significantly reduces sound levels and also sheds some 300 g in weight. The silencers fitted to the 4-strokes feature a new aluminum sleeve profile and new silencer cap, in addition to modified internals. Adding a longer connecting pipe to the silencer means the connection between the header and the silencer is moved further forward. This makes it possible to dismantle the exhaust system without having to remove the shock absorber and provides easier access to the shock absorber.
One aim of KTM’s engineers during the development of the new SX models was to bring about a further reduction in weight compared with the predecessor generation. The result is that the current SX models have clearly raised the bar once again and are now by far the lightest bikes on the market.
All models for model year 2019 are equipped with the revolutionary, super-lightweight WP AER 48 upside-down fork, which has a 48 mm inner fork tube diameter and an air spring unit, and was developed by WP in close collaboration with KTM. Each of the two fork legs has a separate function – damping is on the right, while air spring is on the left. The left fork leg features a twin-chamber system with an encapsulated air cartridge designed to prevent loss of pressure in the event of a complete malfunction. If a leak occurs in the outer seal, the pressure in the cartridge ensures that the shock absorbing function is retained. It incorporates a single air valve, making it possible to adjust
the air suspension easily to changing conditions, such as a new rider with a different weight. No special tools are required, but simply a fork air pump that is supplied as standard with each bike. Damping adjustments to compensate for the track conditions and the rider’s preferences can be made by simply twisting a dial on the upper side of the right fork leg for compression, rebound at the bottom, 30 clicks in each case.
KTM has provided new settings for both the damping characteristics and responsiveness of the WP AER 48 fork for model year 2019
Extremely high-quality CNC milled triple clamps have been something of a KTM trademark for many years now. They are a major factor behind the precise handling characteristics and, with their increased stiffness, enhance the overall performance of the fork. For model year 2019, the upper triple clamp has been made even stiffer and has a 22 mm offset like the predecessor models. It has been matched to the improved frame stiffness and flex characteristics of the new fork to improve both handling and stability. Rubber inserts for the handlebar mount noticeably reduce vibrations in the handlebar and enable the handlebar to be fixed in two positions. A hourmeter mounted on the upper triple clamp tracks the total run time and reminds the rider when the next maintenance is due.
A chassis only does its job perfectly when all the components work together as they should. For this reason, WP Suspension has further developed the DCC (dual compression control) shock absorber as part of the entire frame and swingarm architecture, including the linkage, and ensured that it matches the WP AER 48 fork perfectly. The shock absorber features anodized components and, as a sophisticated high-end product, is far superior to the shock absorbers of numerous other manufacturers. An upgraded main piston and new settings have resulted in optimized damping characteristics that match the modified front end setup perfectly. The shock absorber is fully adjustable, including rebound and high/low-speed compression damping, so that any rider is able to tune the chassis perfectly to any track conditions.
MAP SELECT SWITCH
All 4-stroke models are provided with a multifunctional map select switch, which includes a traction control function, a launch control function and additional power curve functions.
With its new setting, the traction control function provides even more traction and control over the bike when accelerating, par- ticularly 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 by pressing the two buttons. This reduces maximum revs at the start of a race to control power and make lightning fast starts out of the gate and into the first turn easier. As a result of a modified setup, the launch control function now automatically benefits from simultaneously having the traction control function activated, as wheel spin is reduced in order to deliver maximum traction. The EFI indicator lights mounted on the upper triple clamp enables the rider to see when the function is activated. In addition to the standard configuration, the rider also has the possibility of selecting a more aggressive map.
The ergonomically optimized design of the new seat features
an improved seat contour and more comfort for the rider. Now incorporating newly developed silicon strips on the seat area, it gives the rider more grip and a better feel. The seat fixing is made now laterally with one long screw, which simplifies removal.
Yet another KTM innovation – all SX models are equipped as standard with a new plug-in stand for the rear wheel axle made of injection molded plastic, which can also be used as a spacer for the front wheel during transport. It prevents the fork from being compressed during transport and thus reduces static pressure on the air cartridge.
New modern graphics emphasize the sports character of the cutting-edge motocross bikes in the SX model range for 2019.
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 fitted with Geomax MX-3S tires, Dunlop’s latest MX generation.
In addition to experts from the KTM R&D Department and KISKA Design, all KTM factory riders were involved 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 finest detail. The new plastic parts provide the rider with perfect ergonomics and contact points, plus a maximum in terms of freedom of movement. An excellent example of the intelligent design concept can be seen in the fenders both front and rear. As a result of the well thought out structure and mounting arrangements, they feature maximum stability combined with extremely low weight.
The SX generation models in model year 2019 sport a tapered handlebar made of high strength aluminum alloy from NEKEN.
A handlebar mount with rubber inserts allows the handlebar to be fixed in two different positions. All models are fitted with ODI vulcanized grips on the right-hand side. Comfortable lock-on grips from ODI that require neither glue nor wire are fitted on the left-hand side. An upgraded slide pad featuring a newly designed cover can now be fixed even more securely on the handlebar.
KTM’s offroad bikes have always been fitted with Brembo high-tech brakes as standard. They are teamed up with lightweight Wave brake discs.
KTM 250 SX-F
KTM 250 SX-F Winning the MX2 World Championship once again is testimony to the performance and handling of the KTM 250 SX-F – it was the latest and most powerful bike in its class. But it doesn’t stop there – with its new KTM 250 SX-F, KTM is taking yet another step forward – it remains the first choice for both amateurs and professionals, a winning bike the competition can hardly keep up with. With numerous refinements to the chassis and engine, it is now faster than ever before.
ENGINE MANAGEMENT SYSTEM
The state-of-the-art Keihin engine management system with electronic fuel injection features a 44 mm throttle body. As a result of the inno- vative positioning of the injector, the engine responds immediately, de- livers enormous power and guarantees perfect atomization of the fuel with the upstreaming air. There are also separate systems available for cold start and idle adjustments. A modified throttle cable mount provides for a smoother routing of the cables and much easier access. An optimized seal for the MAP (manifold air pressure sensor) means the system is now even more reliable than ever before. The control unit features new maps adapted to the new exhaust system and cylinder head and activates the traction and launch control functions. There are also different maps available for specific power curves depending on which gear is currently engaged. This information is provided by the gear position sensor.
The KTM 250 SX-F crankshaft features a short connecting rod with a plain big (bottom) end bearing with two force-fitted shells running directly on the crank pin. This design is a key prerequisite 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, which is an important customer benefit in terms of waiting times, the amount of work required and costs.
As is the case with all KTM 4-stroke bikes, the KTM 250 SX-F can also be started at the push of a button – an invaluable benefit when the going gets tough. A strong starter motor from Mitsuba and a reliable starter drive ensure that the engine starts every time.
ENGINE CASE & COVERS
The die-cast engine case has been designed to
reduce weight and provide a very centralized shaft configuration. This has resulted in a single-cylinder engine that is both short and compact with excellent centralization of masses. The covers with their modern surface structure are designed to reduce wear caused by the rider’s boots.
The centerpiece of the compact DOHC engine is a cutting-edge cylinder head, featuring two overhead camshafts driving titanium valves (intake 32.5 mm, exhaust 26.5 mm) via super lightweight cam followers with a hard DLC (Diamond-Like Carbon) coating.
To provide optimized power delivery, the exhaust cam- shaft features new timing.
Inside the short-stroke cylinder, which has a bore of 78 mm, there is 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. As a result of the low oscillating masses, the engine delivers an extremely lively performance.
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-re- sistant 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.
It is common knowledge that the KTM 250 SX-F single-cylinder is the most powerful engine in MX2 competition. With updates to the valve timing, exhaust system, air filter box and engine management system, the engine now boasts an unbeatable power curve throughout the entire rpm range to its maximum of 14,000 rpm. Its compact architecture contributes to an excel- lent centralization of the masses. Combined with a low engine weight of 25.9 kg, this is a major reason for the bike’s easy han- dling and rideability – and that, including the extremely useful E-starter. In short, the combination of compact engine layout and unrivaled performance make the KTM 250 SX-F once again an undisputed winner – for both amateurs and professionals.
To balance out the mass forces, the engine in the KTM 250 SX-F is fitted with a multifunctional balancer shaft, which also drives the coolant pump and the timing chain.
The KTM 250 SX-F delivers power from the engine to the rear wheel via a reworked 5-speed transmission, which offers the additional benefits of maximum durability and reliability. The gear ratios have been taken over from its predecessor. KTM’s advanced No-Dirt technology is used for the gear shift lever to prevent mud and dirt from fouling the lever joint and thus guar- antees reliable gear changing at all times. All 4-stroke engines are equipped with a gear position sensor to be able to select a different engine power curve in each gear.
KTM 350 SX-F
The racing career of the KTM 350 SX-F is an unrivaled success story. It started back in 2010, its first year on the market, when KTM decided to enter the bike in its first race events. Without much ado, KTM’s factory rider Tony Cairoli went out on the 350 and won the MX1 World Championship, an event in which the riders normally go to the starting line on 450cc bikes. Since then, the KTM 350 SX-F has continually added more power and torque so that it has now almost reached the power level of a 450. What remains is its extremely agile handling, which is comparable to that of a 250cc bike – it sums up the basic concept and the reason for the success it achieved right from the start.
The KTM 350 SX-F is fitted with an E-starter as standard, which gives the rider an undisputed advantage when the going gets tough in the heat of battle. As a result of the starter motor from Mitsuba and the well-proven starter drive, the engine starts easily and reliably every time.
ENGINE CASE & COVERS
The lower weight and a very centralized shaft configuration is due in part to the design of the die-cast engine case. This has result- ed in a short and compact single-cylinder engine with excellent centralization of masses. The modern surface structure of the covers is designed to reduce wear caused by the rider’s boots.
The newly developed DS (diaphragm steel) clutch in the KTM 350 SX-F is operated by a hydraulic system from Brembo, which ensures an extremely precise and easy action. It is fitted with a one-piece outer clutch hub and a primary gear made of high strength billet steel. Its compact, rivetless construction contributes to the compact design of the engine. This guarantees unbeatable reliability, and 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 compact engine of the KTM 350 SX-F weighs in at a mere 26.6 kg. In model year 2019, it comes up to the gate with a new clutch, optimized transmission, plus an upgraded and lighter DOHC cylinder head, and more power than ever before. Its powerful engine characteristics are due among other things to the lightweight titanium valves and DLC (Diamond-Like Carbon) coated cam followers. It also comes with state-of-the-art electronic fuel injection and an E-starter, and features a wide rpm range, excellent performance and incredibly good rideability.
The design of the balancer shaft is evidence of the amazing innovative power of KTM – it has a variety of functions, such as balancing out mass forces while at the same time driving the coolant pump and the timing chain.
The upgraded cylinder head of the KTM 350 SX-F, with the same architecture as its predecessor, is 200 g lighter. The two overhead camshafts with friction optimized, DLC (Diamond-Like Carbon) coated cam followers and the four lightweight titanium valves (intake 36.3 mm, exhaust 29.1 mm) have also been retained. The maximized flow rate delivers an optimized power curve for outstanding performance curve throughout the entire rpm range to its maximum of 13,400 rpm. The engine generates maximum output of 57 bhp. Any other questions?
CYLINDER & PISTON
A completely reworked and absolutely reliable and durable 5-speed transmission is fitted to the KTM 350 SX-F. Since the individual gear ratios are perfectly matched to the power delivery of the engine and its displacement, they were retained for model year 2019. KTM’s advanced No-Dirt technology is used for the gear shift lever to prevent mud and dirt from fouling the lever joint and thus guarantees reliable gear changing at all times. With a gear position sensor fitted as standard in all 4-stroke engines, the engine management system can call up the ideal power curve, whatever gear is currently selected.
Inside the short-stroke cylinder, which has a bore of 88 mm, there is a 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 14:1. It features a partic- ularly rigid structure, combined with low weight. The engine delivers an extremely lively performance due to the low oscillating masses.
KTM 450 SX-F
When maximum power is needed, there is no alternative to the stunning KTM 450 SX-F. Its performance has been demonstrated in the world’s toughest competitions. Ryan Dungey rode the bike to win the AMA 450 Supercross World Championship 2017 and Tony Cairoli also rode it to win the MXGP World Championship. In model year 2019, the SOHC single-cylinder bike is more powerful than ever before. With its updated, compact SOHC engine, delivering even more explosive, but controllable power, it is the weapon of choice for Supercross and Moto- cross factory teams. Now fitted with a new chassis, the KTM 450 SX-F boasts outstanding handling and absolutely limitless stability, making it the fastest 450cc motocross bike KTM has ever built.
The KTM 450 SX-F is now fitted with a new 4-speed transmission, which is designed to ensure maximum durability and reliability. The gear ratios from the previous transmission system, which are perfectly matched to the performance characteristics of the large displacement single-cylinder engine, have been retained. KTM’s advanced No-Dirt technology is used for the gear shift lever to prevent mud and dirt from fouling the lever joint and thus guarantees reliable gear changing at all times. A gear position sensor fitted as standard to all 4-stroke engines enables the engine management system to select the power curve that perfectly matches the gear currently engaged. The KTM 450 SX-F will be available on the
US market with a 5-speed transmission, since US customers use the bikes on faster tracks and in the desert.
KTM has placed the crankshaft of the KTM 450 SX-F in an ideal position close to the center of gravity, which results in superb handling. A short connecting rod contributes to the compact design of this lightweight engine, which features a snappy power delivery, a well-balanced moment of inertia and – related to it – excellent traction and rideability. The crankshaft has a plain big (bottom) end bearing with two force-fitted shells running directly on the crank pin, which is lubricated by the engine’s high-pressure lubrication system. This design benefits the bike owner, since crankshaft service intervals are extended.
CYLINDER & PISTON
The engine of the KTM 450 SX-F has a short and light cylinder with a bore of 95 mm. An extremely light bridged box-type piston keeps vibrations down and pushes up the rpm. It has a compression ratio of 12.75:1.
The side-mounted balancer shaft also drives the coolant pump. Due to the low oscillating masses of the 450cc engine and its perfect balance, vibration levels are kept to a minimum – even with the engine running at its highest rpm.
ENGINE CASE & COVERS
The design of the die-cast engine case has enabled the weight to be reduced and the shaft configuration to be centralized. This has resulted in a single-cylinder engine that is both short and compact with excel- lent centralization of masses. The covers with their modern surface structure are designed to reduce wear caused by the rider’s boots.
As is the case with all KTM 4-stroke bikes, the KTM 450 SX-F starts by simply pressing a button. Particularly when the going gets tough in motocross event, an E-starter can give the rider an invaluable advantage.
ENGINE MANAGEMENT SYSTEM
The KTM 450 SX-F employs a state-of-the-art Keihin engine management system with electronic fuel injection and a 44 mm throttle body. The instantaneous response of the engine, the virtually inexhaustible power and the perfect atomization of the fuel with the upstreaming air are due to the innovative positioning of the injector. There are also separate systems available for cold start and idle adjustments. A modified throttle cable mount provides for a more direct routing of the cables and much easier access. An optimized seal for the MAP (manifold air pressure sensor) means the system is now even more reliable than ever before. The control unit features new maps adapted to the new exhaust system and cylinder head and activates the traction and launch control functions. There are also different maps available for specific power curves depending on which gear is currently engaged. This information is provided by the gear position sensor.
The newly developed SOHC cylinder head in the KTM 450 SX-F is far more compact than his predecessor, is 15 mm lower and 500 g lighter. This results in an optimized centralization of masses, resulting in further improved handling. A new overhead camshaft positioned closer to the center of gravity controls the intake and exhaust flow through optimized ports. This activates four ultra-lightweight titanium valves (intake 40 mm, exhaust 33 mm) via extremely rigid rocker arms, which are DLC (Diamond-Like Carbon) coated on the intake side. The actuating mechanism is now driven by a shorter timing chain and friction-optimized chain guides and makes engine speeds of up
to 11,500 rpm possible. The new cylinder head guarantees more controllable power delivery and gives the KTM 450 SX-F unparalleled peak performance.
The KTM 450 SX-F is equipped with a DDS (damped diaphragm steel) clutch developed by KTM with a non-wearing steel outer clutch hub and extremely heat-resistant steel clutch plates. The clutch can be operated with little effort, due to the use of a diaphragm spring instead of conventional coil springs. The diaphragm spring also cre- ates space to accommodate a clutch hub with integrated damping system for optimized traction and a long service life. The Brembo hydraulic clutch has an easy and precise action.
KTM has taken the successful KTM 450 SX-F powerhouse and upgraded it for model year 2019, giving it even more compact dimensions, with a weight reduced to 27 kg and explosive power delivery over the entire rpm range. Now fitted with a new, compact cylinder head and the latest electronic fuel injection, the engine now has an even better power delivery and delivers an unrivaled peak power of 62 bhp. Including the E-starter, this bike has the lightest 450cc engine in the entire motocross segment.