Motocross Bikes
2021KTM 50 SX
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The 2021 KTM 50 SX is a competitive mini off-road motorcycle designed for young riders aged 4-8 years old entering motocross. Featuring a lightweight 49cc two-stroke engine with automatic clutch and modern WP suspension, it combines KTM's racing heritage with beginner-friendly handling. Best known for its aggressive styling and reliable performance on dirt tracks and trails.
- Capacity
- 49.0 ccm
- Engine
- Single, two-stroke
- Gearbox
- 1-speed
- Dry weight
- 41.5 kg
- Seat height
- 684 mm
- Power
- 5.4 HP (4.0 kW)
What’s new for the 2021 KTM 50 SX
vs the 2020| Spec | 2020 | 2021 |
|---|---|---|
| Front suspension | WP upside-down Ø 35 mm | XACT 35 WP Upside-Down fork, Ø 35 mm |
| Rear suspension | WP shock absorber | XACT WP mono shock |
| Front brakes | Single disc. Four-piston calipers. | Single disc |
| Rear brakes | Single disc. Two-piston calipers. | Single disc |
Other years
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
How it rides
Editorial estimate from the spec sheet - not lab tested- Best for
- It exists purely to teach a child the fundamentals of balance, throttle control, and off-road riding in a safe, low-powered package.
- Built for
- It behaves like a purpose-built miniature dirt bike, docile and forgiving with an automatic single-speed gearbox that removes clutch and shifting complexity so a child can focus on riding.
- Not ideal for
- It is not suitable for adults, taller teens, road use, touring, or anyone seeking real speed or highway capability.
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
- 49.0 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
- Compression
- 12.5:1
- Cooling system
- Liquid
- Fuel system
- Carburettor
- Starting
- Kick
- Lubrication system
- Mixture oil lubrication
Transmission
- Gearbox
- 1-speed
- Transmission type
- Automatic
- Final drive
- Chain
- Clutch
- Centrifugal
Dimensions & weight
- Wheelbase
- 1029 mm
- Seat height
- 684 mm
- Dry weight
- 41.5 kg
- Fuel capacity
- 2.30 litres
- Ground clearance
- 252 mm
Chassis & suspension
- Frame
- 25CrMo4 steel central-tube frame
- 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
- 180 mm
- Rake (fork angle)
- 24.0°
- Trail
- 90 mm
Brakes & wheels
- Front brakes
- Single disc
- Front brakes diameter
- 160 mm
- Rear brakes
- Single disc
- Rear brakes diameter
- 160 mm
- Front tyre
- 60/100-12
- Rear tyre
- 2.75-10
Other
- Color options
- White/Orange
Specs last verified against published sources: .
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 | 2006 | 2011 | 2017 | 2021 | 2022 | 2027 |
|---|---|---|---|---|---|---|
| Capacity | 49 cc | 49 cc | 49 cc | 49 cc | 49 cc | 50 cc |
| Dry weight | 39 kg | 40 kg | 42 kg | 42 kg | 42 kg | 44 kg |
| Seat height | 650 mm | 684 mm | 684 mm | 684 mm | 665 mm | 653 mm |
| Fuel capacity | 1.8 L | 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?
The 2021 KTM 50 SX has a Capacity of 49.0 ccm (2.99 cubic inches).
What engine power does the KTM 50 SX have?
The 2021 KTM 50 SX has a Power of 5.4 HP (4.0 kW).
How many gears does the KTM 50 SX have?
The 2021 KTM 50 SX has a Gearbox of 1-speed.
How much does the KTM 50 SX weigh?
The 2021 KTM 50 SX has a Dry weight of 41.5 kg (91.5 pounds).
Shop this bike
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The 2021 KTM 50 SX is a top-of-the-line dirt bike designed for young riders who are ready to take their skills to the next level. With its powerful 2-stroke engine and lightweight chassis, this motorcycle offers impressive speed and control on the track. The adjustable suspension and hydraulic disc brakes provide a smooth and responsive ride, giving young racers the confidence to tackle even the toughest terrain. As a parent, I appreciate the high level of safety features included in the 2021 KTM 50 SX, making it a reliable choice for young riders to develop their skills while staying protected.
Overall, the 2021 KTM 50 SX is an outstanding motorcycle that combines speed, agility, and safety in one impressive package. Young riders will love the thrills it provides on the track, while parents can have peace of mind knowing their child is riding a well-built and reliable bike. Whether your child is just starting out in the world of dirt biking or is already a seasoned competitor, the 2021 KTM 50 SX is a fantastic choice for riders of all skill levels.
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