Motocross Bikes
2021KTM 50 SX Factory
27 fields on record
The 2021 KTM 50 SX Factory is a high-performance minibike designed for young riders and beginners entering competitive motocross. Powered by a potent 49.8cc two-stroke engine with DOHC technology and an FMF silencer, it delivers sharp throttle response ideal for learning racecraft. Known for its rigid central-tube frame, advanced WP suspension, and professional-grade components, this bike punches above its weight class for serious youth competition.
- Capacity
- 49.8 ccm
- Engine
- Single, two-stroke
- Gearbox
- Not on record
Know it? Add it → - Dry weight
- 41.5 kg
- Seat height
- 665 mm
- Power
- 5.4 HP (4.0 kW)
How it rides
Editorial estimate from the spec sheet - not lab tested- Best for
- It is a purpose-built entry-level motocross minibike designed to teach children the fundamentals of off-road riding in a controlled, race-oriented package.
- Built for
- The two-stroke engine, automatic centrifugal clutch, and factory-spec WP suspension give it a light, playful, eager-to-turn character suited to learning MX tracks.
- Not ideal for
- It is not suitable for adult riders, road use, touring, or carrying a passenger.
Scores are derived from the spec sheet using the same model across every bike, so they compare like for like.
Will it fit you?
Worked out in your browser - nothing is sent to usEngine
- Capacity
- 49.8 ccm
- Power
- 5.4 HP (4.0 kW)
- Engine type
- Single, two-stroke
- Power/weight ratio
- 0.1301 HP/kg (dry)
- Bore x stroke
- 39.5 x 40.0 mm
- Fuel system
- Carburettor
- Starting
- Kick
- Ignition
- Seletra 2p D36 EMS
Transmission
- Transmission type
- Automatic
- Final drive
- Chain
- Clutch
- Centrifugal
Dimensions & weight
- Wheelbase
- 1026 mm
- Seat height
- 665 mm
- Dry weight
- 41.5 kg
- Fuel capacity
- 2.30 litres
- Ground clearance
- 252 mm
Chassis & suspension
- Frame
- Central-tube frame with double-cradle
- Front suspension
- XACT 35 WP Upside-Down fork, Ø 35 mm
- Rear suspension
- XACT WP mono shock
- Front wheel travel
- 205 mm
- Rear wheel travel
- 185 mm
- Rake (fork angle)
- 24.0°
Brakes & wheels
- Front brakes
- Single disc
- Front brakes diameter
- 160 mm
- Rear brakes
- Single disc
Other
- Color options
- White/Orange/Blue/Red
Compiled from manufacturer documentation and user contributions, corrected on an ongoing basis. Spotted something wrong? Tell us.
What changed, year to year
Differences highlighted| Specification | 2021 | 2022 | 2024 | 2025 | 2026 |
|---|---|---|---|---|---|
| Capacity | 50 cc | 49 cc | 50 cc | 50 cc | 50 cc |
| Dry weight | 42 kg | 42 kg | 44 kg | 44 kg | 44 kg |
| Seat height | 665 mm | 665 mm | 653 mm | 653 mm | 653 mm |
| Fuel capacity | 2.3 L | 2.3 L | 2.3 L | 2.3 L | 2.3 L |
Illustrative - generated automatically by diffing the year records already on file, not a manufacturer-published changelog.
Rider Reviews
Common questions
What is the engine size of the KTM 50 SX Factory?
The 2021 KTM 50 SX Factory has a Capacity of 49.8 ccm (3.04 cubic inches).
What engine power does the KTM 50 SX Factory have?
The 2021 KTM 50 SX Factory has a Power of 5.4 HP (4.0 kW).
How much does the KTM 50 SX Factory weigh?
The 2021 KTM 50 SX Factory has a Dry weight of 41.5 kg (91.5 pounds).
Shop this bike
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The 2021 KTM 50 SX Factory is a top-of-the-line motocross bike for young riders. With its lightweight and agile design, this motorcycle offers impressive performance on the track. The bike is equipped with a powerful 2-stroke engine, hydraulic clutch, and fully adjustable suspension, making it a competitive choice for young riders looking to take their skills to the next level. The KTM 50 SX Factory also features a race-inspired graphics package, adding a stylish touch to its high-performance capabilities.
Overall, the 2021 KTM 50 SX Factory is a solid choice for young motocross enthusiasts looking for a high-performance bike. With its advanced features and race-ready design, this motorcycle offers an exhilarating riding experience for young riders looking to compete at a high level. Whether you're an aspiring young racer or simply enjoy the thrill of motocross, the KTM 50 SX Factory is sure to impress with its performance and style.
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