Built around KTM's enduro - offroad motorcycle platform, the 2025 KTM 125 SX relies on a 124.8 cc (7.6 cu in) liquid-cooled single cylinder, two-stroke powerplant. In factory specification, peak output is rated at 15 HP (10.9 kW), transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 120.2 HP per liter, the engine character is reflecting a performance-oriented street tune that balances strong mid-range pull with an energetic top-end rush.
On the scales, the 125 SX measures 92.4 kg (204 lbs) dry, translating to a power-to-weight ratio of 0.16 HP/kg (6.16 kg per horsepower). Rider ergonomics and chassis geometry center around a 958 mm (37.7 in) seat height — reflecting a long-travel chassis stance that favors ground clearance and off-pavement control, combined with a 1,493 mm (58.8 in) wheelbase engineered for balanced agility and highway composure. The 7.2-liter (1.9 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's KTM archive, this model family spans 23 indexed model years from 2003 to 2025, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
120.2 HP/L
Power-to-Weight
0.16 HP/kg (6.16 kg/HP)
Standover Height
958 mm (37.7 in)
Engine
Displacement124.8 ccm (7.62 cubic inches)
Engine TypeSingle cylinder, two-stroke
Power15.0 HP (10.9 kW))
Bore x Stroke54.0 x 54.5 mm (2.1 x 2.1 inches)
Fuel SystemInjection. Keihin EFI, throttle body 39 mm
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
