2026 KTM 125 SX

Key features

Engine and electronics

• Engine: The 124.8 cc, liquid-cooled, 2-stroke engine is designed for strong performance in the 125 class.
• Electronic Fuel Injection (EFI): EFI and an electronic power valve automatically adjust the fuel-air mixture, eliminating the need for manual jetting and providing more usable power across the rev range.
• Map selection: A handlebar-mounted switch allows riders to select between two engine maps.
• Map 1 (White): Provides a linear power delivery ideal for hard-packed tracks.
• Map 2 (Green): Offers a richer mix for more aggressive power delivery in sandy or loose conditions.
• Electric start: Standard electric start, powered by a lightweight 12.8V lithium-ion battery, allows for fast restarts. 

Chassis and suspension

• Frame: The chromoly steel central double-cradle frame features updated wall thickness and engine mounts designed to optimize flex and improve cornering, saving approximately 300 grams over the previous generation.
• Suspension:
• Front: A 48mm WP XACT air fork offers adjustable air pressure, compression, and rebound damping. An air pump for adjustment is included.
• Rear: The WP XACT monoshock with linkage has updated settings from the KTM Factory Racing teams and features tool-free, hand-adjustable dual compression control for quick changes.
• Brakes: Braking is handled by high-performance Brembo units, with a two-piston caliper on a 260mm disc in the front and a single-piston caliper on a 220mm disc in the rear.
• Tires: The bike comes equipped with Dunlop Geomax MX34 tires, which feature a new compound and pattern for improved traction and damping. 

Minor updates for 2026

• Styling: Updated graphics feature a more vivid orange, with flashes of red on the fork guards and tank spoilers. The seat cover and frame protectors are now black.
• Radiator cap: A new, easier-to-access standard thread radiator cap.
• Wiring harness: Improved routing of the wiring harness for better protection against dirt.
• Fuel system: A new protector cap has been added for the fuel-link quick-lock system to enhance durability and prevent dirt intrusion. 

Specifications

Feature Detail Engine1-cylinder, 2-stroke, 124.8 cc Transmission 6-speed Start Electric starter Fuel System Electronic Fuel Injection (EFI) Clutch Wet multi-disc DS clutch, Brembo hydraulics Weight (without fuel)~204lbs (92.4 kg) Seat Height37.7 in (958 mm) Fuel Capacity1.9 gal (7.2 L)