The New KTM SX RANGE 2023
2023 MOTOCROSS RADICAL INNOVATION
In the rough and tumble world of competitive motocross, KTM has long been a dominant leader in innovation, starting the trend way back in 1986 when it became the first manufacturer to produce an MX machine with front and rear disc brakes.
The KTM 350 SX-F was another experimental and successful debut for KTM - not mentioning an almost unending list of 2-stroke engine innovations in the 2-wheel offroad motorsport realm. The success of this relentless pursuit of always being at the cutting edge is obvious.
For 2023, that trend continues.
WELCOME TO THE ERA OF ‘SMARTERCROSS’
KTM has won 5 AMA 450 supercross titles since 2015, 30 of 51 possible MX World titles since 2000, 12 of the last 14 MX2 World titles, and 8 MXGP titles since 2010. In fact, in many instances, these represent more titles than all competitors combined - all of these victories can be attributed to intense R&D input.
For model year 2023, the full-sized KTM Motocross stable has undergone a complete refresh, with an array of technological advancements across the entire KTM SX and SX-F range. These changes have come directly from learnings at the track, with racer input being at the forefront.
Now sleeker, slimmer, and designed to provide all riders of any experience level complete control, The 2023 KTM SX range of motocross weaponry is ready to make a statement.
4-STROKE
The 2023 KTM SX-F range once again comprises three core models, namely the rev-happy KTM 250 SX-F, giant-killing KTM 350 SX-F, and the range-topping KTM 450 SX-F.
The latter is the perfect example of advanced engineering techniques at a Factory Racing level finding their way on a production motorcycle.
The KTM 450 SX-F offers a peak power of over 63 hp at an overall weight of just 26.8 kg, approximately 300 g less when compared to the previous generation. Chassis engineers positioned the engine closer to the center of gravity, resulting in greatly improved handling and maneuverability, which together with the benefits of mass centralization and reduced weight of the powerplant, the anti-squat behavior of the chassis was significantly improved.
The 2023 KTM 250 SX-F now features a more compact engine, with the total engine height reduced by 8 mm to improve mass centralization and reduce weight. All major components and shaft arrangements are carefully designed to benefit the performance and handling characteristics of the overall package. This has resulted in an outstanding, high revving performance engine with over 47 hp peak power and 14,000 rpm rev-limit, with an overall engine weight of only 26.11 kg.
Whilst each capacity in the 2023 KTM SX-F has received major refinements, the biggest advancement comes from a change in the position of the engine within the frame.
By rotating the engine backward by 2 degrees - and lowered slightly on the 2023 KTM 250 SX-F - the 4-stroke stable benefits from improved mass centralization, dramatically improving handling dynamics and squat behavior on acceleration.
The valve covers across the 2023 KTM SX-F have also seen a reduction in the number of mounting screws, with only two needed, along with a single oil spray jet that guarantees efficient cooling while keeping the weight low.
SERVICEABILITY
Another focus was put on the new 2023 KTM SX-F range is serviceability. Draining noses for liquids and added service markers on the engine (▲) clearly show where to use washers, making maintenance and service easier and more accessible to different levels of riders. Added lock positions for the cam chain also improve the serviceability of the valve train.
CYLINDER HEADS
KTM 450 SX-F
The redesigned SOHC cylinder head is incredibly compact and lightweight using a short profile with the camshaft located as close to the center of gravity as possible. Lightweight valves are actuated via a DLC coated rocker arm and feature optimized timing, specifically designed to deliver precise levels of torque and throttle response. The diameter of the intake valve is 40 mm, while on the exhaust it is 33 mm. Redesigned intake ports allow higher flow coefficients, resulting in a more efficient and powerful engine.
KTM 350 SX-F
The fully redesigned DOHC cylinder head features finger followers with a DLC coating resulting in minimal friction and optimal performance. These actuate large titanium valves - 36.3 mm intake and at the 29.1 mm exhaust - which at the 13,400-rpm rev limit, open and close multiple times each second to produce the optimal fuel/air mixture. The new 29.1 mm exhaust valve comes as a result of the redesigned engine to deliver an optimized gas flow with valve timings adapted to work perfectly in harmony with the redesigned camshaft.
KTM 250 SX-F
The fully redesigned DOHC cylinder head features finger followers with a DLC coating, actuating large titanium valves - 32.5 mm intake and 27.5 mm exhaust. The new 27.5 mm exhaust valve is a result of the new bore/stroke ratio and narrowed inlet port, which together deliver an optimized gas flow for a more responsive engine. Valve timings have been adapted to the new valve measurements, working in perfect harmony with the redesigned camshaft.
The cylinder of 81 mm bore, and 48.5 mm stroke (MY22 = 78/52.3 mm) houses an extremely lightweight (150g) forged bridged-box-type piston. This new combination raises the compression ratio to 14.5:1 for added torque and peak performance.
For improved serviceability and maintenance work within the engine, the redesigned camshaft bearing bridge is screwed down which increases stiffness. Also, the head gasket comes with a new “stopper design”, improving the sealing function under extreme conditions.
GEARBOX
A redesigned, lightweight 5-speed gearbox by Pankl Racing Systems ensures the highest level of durability and reliability. The redesign is focused around a weight-optimized shift shaft, reducing the operating force of gear changes.
2-STROKE
The 2023 KTM 2-stroke SX range sees the return of the KTM 125 SX and wildly popular KTM 250 SX, with a new Open Class entry in the form of the KTM 300 SX.
The 2023 KTM 2-stroke SX range sees the biggest spread of advancements in the 2023 Motocross line-up, with benefits aimed at usability and performance - not to mention bringing 2-stroke technology into the modern MX era.
ELECTRONIC FUEL INJECTION
For the first time, the full-sized KTM SX range receives electronic fuel injection across the range.
Together with Keihin, a 39 mm throttle body was developed to withstand the harsh and fullthrottle demands of competitive motocross. This is done by a specifically tuned ECU from Vitesco Technologies works in conjunction with the Keihin throttle body to always deliver the correct air-fuel mixture by constantly analyzing water temperature, air temperature, ambient pressure, the pressure within the crankcase, rpm, and throttle position.
Newly designed injectors also work to provide an optimal burn rate, with improved Sauter mean diameter (SMD), producing a finer spray of fuel for a cleaner ignition and less fuel wastage.
Overall, the 2023 KTM SX range provides riders with a real-world alternative to 4-strokes, offering optimal power delivery in any condition without the need to rejet carburetors.
REED VALVE
The reed valve case has received an important design update, with newly added plastic flaps on the outside of the reed valve case for better sealing of the entire intake tract. This new design negates over-fueling in extreme up- or downhill sections with no bogging down or running rich. Boyesen continues to supply the carbon membranes for the reed valve case.
ELECTRIC POWER VALVE
With the introduction of EFI, the power valve is controlled according to the throttle position and engine RPMs. Being auto-calibrating, there’s no more hassle with incorrect power valve adjustments, with the EMS calculating the ideal position automatically and opening both the main exhaust and lateral exhaust ports via newly developed kinematics, activated via an actuator. This results in linear and predictable power delivery at all throttle inputs.
EXHAUST
The 2023 KTM SX range benefits from a more compact exhaust header design, achieving improved ground clearance, reducing the risk of any damage from deep ruts, or external objects. The silencer also benefits from the compact treatment, crafted from lightweight aluminum, and stylishly finished off in a premium black coating.
ENGINE MAPS
With the addition of EFI and electric power valve, it was possible to introduce different engine maps on the 2-stroke SX range, easily toggled via the handlebar switchgear. Map 1 provides a standard, more mellow map for linear, predictable power, while Map 2 is more aggressive, with immediate throttle response and a more crisp, explosive power output.
ELECTRIC START
Another new addition to the 2023 KTM SX range, is electric start which is easily toggled via a newly designed combined Start/Stop switch on the right side of the handlebar, The starter motor comes without any intermediate shaft, saving weight and allowing a compact engine design with perfect integration and protection from roost. Weight-saving has gone even further, with an ultra-lightweight 12,8V 2 Ah Lithium-Ion battery placed under the seat close to the center of gravity.
KTM 300 SX
The most powerful 2-stroke weapon in the KTM SX stable, the KTM 300 SX enters the race as a new choice of firepower into the MX Open category. Aimed at racers looking for maximum power with the least possible weight, the 2023 KTM 300 SX offers simplicity and low maintenance. With more than 57 hp, and an overall weight of just 23,9 kg, the new 300 SX engine sets the benchmark when it comes to power to weight ratios and is designed to provide more torque than any previous 2-stroke engine without losing its typical highrevving lightweight 2-stroke character.