The 2023 KTM SX motocross range adds revolutionary tech features, a new two-stroke EFI system, and a KTM 300 SX for the first time. A bold new two-stroke platform headlines a radical overhaul for the 2023 KTM SX motocross range, with new features and parts across the board.
The new 2023 KTM SX two-stroke models feature electronic throttle body fuel injection for the first time, replacing the transfer port injection (TPI) system introduced in 2017 for the brand’s enduro models. KTM Australia told bike sales that the new system is “much more complex” than the original TPI system seen in the EXC range.
Fuel injection by Keihin replaces the Mikuni TMX carburetor. The SXes don’t use the TPI (Transfer Port Injection) found in the EXC off-road models. Instead, it has a more traditional fuel injection setup with a 39mm throttle body. Unlike the TPI KTMs, the SXes run premixed fuel—60:1 on the 300 and 250, and 40:1 on the high-revving 125.
As before, the 2023 KTM SX 300 and 250 share the same engine architecture, with the 125 having a 16-pound lighter design.
The power valve is now electronically, rather than mechanically, controlled. KTM claims this will create more mid-range power.
With EFI comes more electronic wizardry that’s new to KTM two-stroke motocrossers. There are two power maps, a throttle position sensor, improved idling, and a cold-start device. Should your ’23 SX hit the deck, a roll-over sensor kicks in to shut the motor down.
Sorry, but the two-strokes don’t get the launch control, traction control, and quick-shifter features that the four-strokes SX-F models boast.
The 2023 KTM SXes all get electric starting. There is no Kickstarter, and you can’t add one—push the button and go.
A new Pankl transmission is dropped into the cases. The 300 and 250 run a five-speed gearbox, while the 125 get a sixth ratio. The DDS clutch is back with Brembo hydraulics.
The chassis is all-new—frame, subframe, swingarm, and WP suspension. The overall goal of the changes is to improve rider comfort.
The frame has new parallel motor mounts to manage the frame’s rigidity. The new forged shock mount has the same goal.
KTM moved the footpegs in a bit. This will make scrubbing easier, and the pegs less likely to get hung up in ruts.
The new die-cast aluminum swingarm is hollow. Rigidity is increased while weight is dropped. There’s also a new rear axle to match the swingarm.
WP redesigned the Xact shock for the 2023 KTM SXes. The shorter body has all-new internals, and it weighs less.
A new hydro-stop is dropped in the WP Xact air fork. This makes the fork less likely to bottom, per KTM. The damping settings have also been refined to reflect the changes in the frame.
The handlebar mounts get an increased gripping surface. This will minimize bar twists in the roughest terrain.
The frame is a combination of aluminum and polyamide. Over at the Husqvarna arm of KTM, the rear subframe has been polyamide and carbon fiber. This is a new hybrid design.
Dunlop Geomax MX33 tires replace last year’s MX3S. The 125 has a 100mm wide rear tire, while the 300 and 250 run a 110. The new Dunlop tires are mounted on an Excel rim laced to CNC-machined hubs.
New angular bodywork reminds you of the significant changes to the KTM SX 300, 250, and 125. Also, it’s slimmer.
KTM has kept the MSRP of the 2023 KTM 300 SX, 250 SX, and 125 SX, well below $10k. The 125 SX is $7949, with the 250 SX bumping the price up to $8949, and the flagship 2023 KTM 300 SX wearing a $9199 price tag.
2023 KTM 300 SX, 250 SX and 125 SX Specs
Type: Single-cylinder 2-stroke
Displacement: 293cc (250: 249cc; 125: 125cc)
Bore x stroke: 72 x 72mm (250: 66.4 x 72mm; 125: 54 x 54.5mm)
Fueling: Keihin EFI w/ 39mm throttle body
Lubrication: Premix @ 60:1 (125: 40:1)
Transmission: 5-speed (125: 6-speed)
Clutch: Wet multi-disc DDS clutch w/ Brembo hydraulics
Frame: Central double-cradle chromoly steel w/ aluminum/polyamide subframe
Handlebar: Tapered aluminum Neken
Front suspension; travel: Fully adjustable WP Xact inverted 48mm fork; 12.2 inches
Rear suspension: Linkage-assisted fully adjustable WP Xact shock; 11.8 inches
Front wheel: 21 x 1.60
Rear wheel: 19 x 2.15
Tires: Dunlop Geomax MX33
Front tire: 80/100 x 21
Rear tire: 110/90 x 19 (125: 100/90 x 19)
Front brake: 260mm disc
Rear brake: 220mm disc
DIMENSIONS and CAPACITIES
Wheelbase: 58.7 inches
Rake: 26.1 degrees
Triple clamp offset: 22mm
Seat height: 37.7 inches
Ground clearance: 13.9 inches
Fuel capacity: 1.9 gallons
Curb weight: 231 pounds (125: 215 pounds)
2023 KTM 300 SX Price: $9199 MSRP
2023 KTM 250 SX Price: $8949
2023 KTM 125 SX Price: $7949