14 August. Friday 2026
KTM 125 SX - 2021 Specifications and Reviews
The 2021 KTM 125 SX is a lightweight two-stroke enduro bike designed for young riders and beginners entering competitive off-road racing. Powered by a 124.8cc single-cylinder engine producing 15 horsepower, it delivers sharp acceleration and nimble handling ideal for motocross and trail riding. Known for its aggressive styling, responsive performance, and affordable pricing, the 125 SX remains a popular choice for developing fundamental riding skills in off-road disciplines.
General information | |
| Price as new | 2.8 Check out the detailed rating of off-road capabilities, engine performance, maintenance cost, etc. Compare with any other bike. |
| Category | Enduro / offroad |
| Year | 2021 |
| Model | KTM 125 SX |
Engine and Transmission Specifications | |
| Driveline | 5/8  x  1/4 (520) O Ring. Primary drive: 22:72. |
| Clutch | Multi-plate clutch, Brembo hydraulics |
| Transmission type | Chain (final drive) |
| Gearbox | 6-speed |
| Cooling system | Liquid |
| Lubrication system | Wet sump |
| Ignition | Kokusan EMS |
| Fuel control | Double Overhead Cams/Twin Cam (DOHC) |
| Fuel system | Injection |
| Bore x Stroke | 54.0 x 54.5 mm (2.1 x 2.1 inches) |
| Power | 15.0 HP (10.9 kW) |
| Engine type | Single cylinder, two-stroke |
| Capacity: | 124.8 ccm (7.62 cubic inches) |
| | |
Brakes, suspension, Frame and wheels | |
| Rear brakes | Single disc |
| Diameter | 260 mm (10.2 inches) |
| Front brakes | Single disc |
| Rear tire | 150-17 |
| Front tire | 110-17 |
| Rear wheel travel | 300 mm (11.8 inches) |
| Rear Suspension | WP XACT Monoshock with linkage |
| Front wheel travel | 310 mm (12.2 inches) |
| Front Suspension | WP XACT-USD, Ø 48 mm |
| Rake (fork angle) | 26.1° |
| Frame type | Central double-cradle-type 25CrMo4 steel |
| | |
Physical measures and capacities | |
| Fuel capacity | 7.50 litres (1.98 US gallons) |
| Ground clearance | 375 mm (14.8 inches) |
| Seat height | 850 mm (33.5 inches) If adjustable, lowest setting. |
| Power/weight ratio | 0.1714 HP/kg |
| Dry weight | 87.5 kg (192.9 pounds) |
Other specs | |
| Maintenance | Find parts, fluids, filters, maintenance tools and service items on eBay |
| Starter | Kick |
| Color options | White/Orange |
Performance Profile & Rider Fit
Best For
Track95%
City10%
Cornering90%
Daily Riding10%
Touring8%
Passenger5%
Rider Profile
| Best For | This is a full-on motocross competition bike best suited to intermediate through expert off-road riders, not beginners or casual road riders. |
| Purpose | Built purely for closed-course motocross racing, it excels at jumps, berms, and rapid direction changes on dirt tracks rather than any street use. |
| Rider Fit | The tall 958 mm seat height, aggressive ergonomics, and demanding 2-stroke power delivery require good rider fitness, strength, and prior dirt bike experience. |
| Character | Light, explosive, and razor-sharp in handling, it rewards aggressive riding with a peaky two-stroke power band and minimal weight to manage. |
| Not Ideal For | It is not suitable for commuting, highway travel, passengers, or riders seeking comfort, storage, or a forgiving low-end power delivery. |
Character map is an editorial estimate based on this bike's specifications, not a lab-tested measurement.
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Rider Reviews
Total comments: 1
MotorcycleDB Review
The 2021 KTM 125 SX is a powerful and lightweight motocross bike that is perfect for riders looking to take their skills to the next level. With its high-performance engine and race-ready suspension, this bike offers unmatched agility and control on the track. The top-of-the-line components and advanced technology make this motorcycle a top choice for competitive riders who demand the best performance from their machine. Whether you're a seasoned pro or a novice rider, the KTM 125 SX delivers an exhilarating and responsive riding experience that is sure to impress. In conclusion, the 2021 KTM 125 SX is a top-of-the-line motocross bike that offers exceptional performance and handling. With its powerful engine and race-ready suspension, this motorcycle is a top choice for competitive riders looking to push their limits on the track. Whether you're a seasoned pro or a novice rider, the KTM 125 SX delivers an exhilarating and responsive riding experience that is sure to impress. If you're looking for a high-performance motocross bike that delivers unmatched agility and control, the 2021 KTM 125 SX is the perfect choice for you.Add a Comment
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