2024 KTM 125 SX Technical Information

KTM isn’t afraid to push the envelope of two-stroke engine development. After giving its 250 XC-W enduro model transfer port injection (TPI) in 2018, the Austrian concern did the same for its 300 XC-W and 150 XC-W in 2019 and 2020, respectively. The two-stroke cross-country racers got the same treatment in 2020.

Following those developments on its off-road models, the Ready to Race brand brought electronic fuel injection (EFI) to its two-stroke motocross bikes last year in the form of throttle body injection (TBI). The 125 SX, 250 SX, and 300 SX were also given electronic power valves, along with a completely new chassis, shorter shock, and updated fork. We were fortunate enough to test preproduction versions of the orange brigade’s trio of premix-burning MX models at RedBud MX, then put the lowest– and highest-displacement options through their paces at Fox Raceway later in the year.

Fast-forward to 2024 and we once again found ourselves with the opportunity to test the 125 SX, which like the rest of KTM’s MY24 full-size motocrossers is equipped with reworked suspension settings and fresh graphics. Read on to find out more about the 125 SX, and see some static and detail shots of it before we publish our first ride review.

After a top-to-bottom overhaul in 2023, KTM gave its smallest-displacement full-size two-stroke motocross bike some minor suspension and graphic updates for 2024. (Mark Kariya/)
Engine is a fuel-injected liquid-cooled two-stroke 125cc single-cylinder. On our in-house Dynojet 250i rear-wheel dynamometer, it’s good for 33.2 hp at 11,000 rpm and 16.1 lb.-ft. of torque at 10,800 rpm. (Mark Kariya/)
Although small-bore two-strokes are generally easy to kick over, KTM insists on electric start for the 125 SX. Hitting the magic button is always nice, regardless of displacement. (Mark Kariya/)
Openings on both sides of the two-piece aluminum/polyamide hybrid subframe is a minor difference between the KTM 125 SX and Husqvarna TC 125, as the latter’s is closed off. (Mark Kariya/)
Some of the sweetest sounds and smells in motocross come from this aluminum silencer. (Mark Kariya/)

KTM keeps the 125 SX’s control area very clean with just four buttons total on both sides of the Neken handlebar. (Mark Kariya/)
Engine start and stop buttons are combined on a single module within thumb’s reach. (Mark Kariya/)
On the left side of the handlebar, you select between two engine maps. Map 1 (white light illuminated) is a lean map while map 2 (green light illuminated) is a rich setting. (Mark Kariya/)
The Austrian concern recommends map 1 for hard-packed tracks and map 2 for sandy courses. (Mark Kariya/)
Brembo hydraulic clutch pull is very light. (Mark Kariya/)

KTM specs its 125cc two-stroke motocross bike with 13/51 gearing. (Mark Kariya/)
Like the rest of the Ready to Race brand’s full-size MX bike lineup, a WP Xact 48mm closed-cartridge air fork is assigned to front suspension duty. (Mark Kariya/)
Standard fork air pressure is 8.3 bar. (Mark Kariya/)
Stock clicker settings for this and other full-size KTM motocross models are listed on the right fork leg. (Mark Kariya/)
Tunable by hand, fork compression damping is adjusted atop the right fork leg with rebound damping on bottom. Stock settings are 12 clicks (out from fully closed) for both. (Mark Kariya/)
Speaking of tool-free adjusters, the WP Xact shock’s are as well with low- and high-speed compression damping on the body and rebound damping on the clevis. (Mark Kariya/)
Shock spring rate is 39 Nm—the softest in KTM’s full-size motocross range. (Mark Kariya/)
Powerful to begin with, Brembo brakes feel extra strong on such a lightweight motorcycle. (Mark Kariya/)
This marks the final year the 125 SX and its larger-displacement two- and four-stroke MX siblings will have Dunlop Geomax MX33 tires, as the 2025 models are equipped with Dunlop Geomax MX34 rubber. (Mark Kariya/)
KTM added some extra purple in the radiator shroud graphics for 2024. (Mark Kariya/)
On <i>Dirt Rider</i>’s automotive scales, the 2024 KTM 125 SX weighs 217 pounds with its 1.9-gallon fuel tank topped up with 40:1 premix. (Mark Kariya/)

2024 KTM 125 SX Specs

MSRP:
$8,099

Engine:
Liquid-cooled, two-stroke single-cylinder

Displacement:
125cc

Bore x Stroke:
54.0 x 54.5mm

Compression Ratio:
N/A

Transmission/Final Drive:
6-speed/chain

Dirt Rider Measured Horsepower:
33.2 hp @ 11,000 rpm

Dirt Rider Measured Torque:
16.1 lb.-ft. @ 10,800 rpm

Fuel System:
EFI w/ 39mm throttle body

Clutch:
Wet, multiplate Diaphragm Steel (DS); hydraulic actuation

Frame:
Central double-cradle chromoly steel

Front Suspension:
WP Xact 48mm fork, air pressure, compression damping, and rebound damping adjustable; 12.2 in. travel

Rear Suspension:
WP Xact shock, spring preload, high/low-speed compression damping, and rebound damping adjustable; 11.8 in. travel

Front Brake:
Brembo 2-piston caliper, 260mm disc

Rear Brake:
Brembo 1-piston caliper, 220mm disc

Tires, Front/Rear:
Dunlop Geomax MX33; 80/100-21 / 100/90-19

Rake/Trail:
26.1°/NA

Wheelbase:
58.7 in.

Ground Clearance:
14.1 in.

Dirt Rider Measured Seat Height:
37.5 in.

Fuel Capacity:
1.9 gal.

Dirt Rider Measured Wet Weight:
217 lb.

Availability:
Now

Contact:
ktm.com

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