First Look At 2023 KTM MX and Off-Road Race Models
The wait is over and KTM’s all new SX and XC models are here in a big way. As expected, all of the models receive a host of updates including the chassis, engine, bodywork, and more that resemble the 2022.5 Factory Edition. While the four-strokes came as expected, the two-strokes received even more updates and feature some groundbreaking designs.
Quite possibly the biggest news is the addition of a 300SX – that’s right, a big-bore two-stroke motocross bike straight from the factory! The current crop of SX bikes from KTM include the 450 SX-F, 350 SX-F, 250 SX-F, 300 SX, 250SX, and 125SX (no 150 SX). The XC range includes the 450 XC-F, 350 XC-F, 250 XC-F, 300 XC, 250 XC, and 125 XC.
At first glance, all the two-strokes now have Electronic Power Valves that are based on throttle position and engine RPM. Continuing with the electronics, the two-strokes now have a mapping switch with two adjustable maps – one standard, linear map and one aggressive, hard hitting map. All two-strokes are now E-Start only with no option for a kickstarter in the cases. A Kehein 39mm Throttle Body feeds the motor with fuel injectors, and gone is the TPi system that we first saw KTM introduce (and is still used on the XC-W models for 2023).
The case reed valve has been updated with “plastic flaps on the outside of the reed valve case for better sealing of the entire intake tract” to potentially eliminate any changes in performance under all conditions. Of course, all of the chassis components have been updated to that of the factory edition that we have seen already.
Some interesting notes upon looking at these bikes are a few things. First, all of the XC/F bikes come equipped with a MX33F/AT81 tire combo instead of the more traditional AT81’s front and rear. Yamaha has equipped their FX bikes with MX3S’s and now MX33’s for quite some time and KTM is jumping on board with something more in line with their race teams. Of course, the SX/F bikes still come standard with MX33’s front and rear.
UPDATE: Additionally, the 350 XC-F and the 250/300XC do have a sixth gear (originally reported as being 5-speeds). The 450 XC-F is still a 5-speed, but in past years we’ve found a way to put the EXC 6th gear in the motor.
For the full press release, read below ~
Two-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 enjoys 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 full-throttle demands of competitive motocross. This is done by a specifically tuned ECU from Vitesco, 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. 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, 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 massive power-, and an overall weight of just 52.6 lb, 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 high-revving lightweight 2-stroke character.
Four-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.
4-STROKE ELECTRONIC FEATURES
The 2023 KTM SX-F range benefits from a number of electronic updates focused on providing the very best experience for riders and helping them get the most from their racing machines.
LAUNCH CONTROL
With the engine at idle, launch control is engaged by pressing the Traction Control and Quickshift buttons simultaneously. This function regulates the amount of power to the rear wheel on takeoff, improving traction and preventing wheelspin under hard acceleration.
TRACTION CONTROL
Traction control is selected to an on or off position from the switch and functions by analyzing throttle input from the rider and the rate at which RPM increases in the engine. If the RPM increases too quickly, the EMS registers a loss of grip and reduces the amount of power to the rear wheel ensuring maximum traction. This provides a distinct advantage on low-traction, dusty hardpack surfaces or in wet or muddy conditions.
QUICKSHIFTER
The new Quickshifter function can be activated or deactivated via the new map select switch, allowing for clutchless upshifts, with the throttle fully opened. A sensor on the shift drum notices the force on the shift lever, sends the signal to the ECU and the ignition timing is interrupted. To prevent unintended shifts and false neutrals, the function is only active from 2nd to 5th gear.
