Motocross Bikes
2021KTM 150 SX
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The 2021 KTM 150 SX is a competitive 144cc two-stroke motocross machine designed for junior and intermediate riders seeking race-ready performance. Known for its lightweight agility and responsive power delivery, it combines proven KTM engineering with Brembo hydraulics and liquid cooling for reliability on the track. This class staple excels in youth motocross competition and provides an accessible stepping stone to higher-displacement racing bikes.
- Capacity
- 144.0 ccm
- Engine
- Single, two-stroke
- Gearbox
- 6-speed
- Dry weight
- 87.5 kg
- Seat height
- 850 mm
- Power
- 11.5 HP (8.5 kW)
What’s new for the 2021 KTM 150 SX
vs the 2020| Spec | 2020 | 2021 |
|---|---|---|
| Seat height | 950 mm (37.4 inches) | 850 mm (33.5 inches) |
| Fuel capacity | 7.00 litres (1.85 US gallons) | 7.50 litres (1.98 US gallons) |
| Front suspension | WP-USD, AER 48, Ø 48 mm | WP XACT-USD, Ø 48 mm |
| Rear suspension | WP shock absorber with linkage | WP XACT Monoshock with linkage |
Other years
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
How it rides
Editorial estimate from the spec sheet - not lab tested- Best for
- Built purely for motocross and cross-country racing on dirt tracks, not for street or commuting use.
- Built for
- A high-strung, revvy two-stroke that rewards aggressive riding, quick gear changes, and an active body position with sharp, flickable handling.
- Not ideal for
- Not suitable for riders wanting a comfortable, relaxed, road-going or touring motorcycle, or anyone seeking passenger capability or long-distance comfort.
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
- 144.0 ccm
- Power
- 11.5 HP (8.5 kW)
- Engine type
- Single, two-stroke
- Power/weight ratio
- 0.1314 HP/kg (dry)
- Bore x stroke
- 58.0 x 54.5 mm
- Cooling system
- Liquid
- Fuel system
- Carburettor
- Starting
- Kick
- Ignition
- Kokusan EMS
- Lubrication system
- Mixture oil lubrication 1:40
Transmission
- Gearbox
- 6-speed
- Transmission type
- Manual
- Final drive
- Chain
- Clutch
- Multi-plate clutch, Brembo hydraulics
Dimensions & weight
- Wheelbase
- 1485 mm
- Seat height
- 850 mm
- Dry weight
- 87.5 kg
- Fuel capacity
- 7.50 litres
- Ground clearance
- 375 mm
Chassis & suspension
- Frame
- 25CrMo4 steel central-tube
- Front suspension
- WP XACT-USD, Ø 48 mm
- Rear suspension
- WP XACT Monoshock with linkage
- Front wheel travel
- 310 mm
- Rear wheel travel
- 300 mm
- Rake (fork angle)
- 26.1°
Brakes & wheels
- Front brakes
- Single disc. Four-piston calipers.
- Front brakes diameter
- 260 mm
- Rear brakes
- Single disc. Two-piston calipers.
- Rear brakes diameter
- 220 mm
- Front tyre
- 80/100-21
- Rear tyre
- 100/90-19
Other
- Color options
- Orange/white/black
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 | 2009 | 2013 | 2018 | 2021 | 2022 | 2026 |
|---|---|---|---|---|---|---|
| Capacity | 144 cc | 144 cc | 144 cc | 144 cc | 144 cc | 144 cc |
| Dry weight | 91 kg | 91 kg | 87 kg | 88 kg | 88 kg | 93 kg |
| Seat height | 985 mm | 992 mm | 960 mm | 850 mm | 950 mm | 958 mm |
| Fuel capacity | 8 L | 7.5 L | 7 L | 7.5 L | 7.5 L | 7.2 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 150 SX?
The 2021 KTM 150 SX has a Capacity of 144.0 ccm (8.79 cubic inches).
What engine power does the KTM 150 SX have?
The 2021 KTM 150 SX has a Power of 11.5 HP (8.5 kW).
How many gears does the KTM 150 SX have?
The 2021 KTM 150 SX has a Gearbox of 6-speed.
How much does the KTM 150 SX weigh?
The 2021 KTM 150 SX has a Dry weight of 87.5 kg (192.9 pounds).
Shop this bike
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The 2021 KTM 150 SX is a powerful and nimble motocross bike that delivers exceptional performance on the track. With its lightweight and compact design, this bike offers excellent maneuverability and handling, making it an ideal choice for riders looking to dominate in the MX2 class. The 150cc two-stroke engine provides impressive power and torque, allowing riders to accelerate quickly and conquer any obstacle on the track. Additionally, the bike's top-notch suspension and braking system further enhance its performance, giving riders the confidence to push their limits.
Overall, the 2021 KTM 150 SX is a top-tier motocross bike that offers impressive performance and agility on the track. With its powerful two-stroke engine, superior handling, and advanced suspension, this bike is well-equipped to handle the demands of motocross competition. Whether you're a seasoned rider or a competitive racer, the 150 SX is a solid choice for those looking to take their motocross skills to the next level.
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