2026KTM 125 SX

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The 2026 KTM 125 SX is a lightweight 2-stroke motocross bike engineered for young and amateur riders seeking competitive performance. Featuring a sharp 124.8cc engine with EFI and WP XACT suspension, it delivers responsive handling and reliability for both training and entry-level racing. This machine is renowned for outstanding agility and value in the junior motocross segment.

Capacity: 124.8 ccm
Engine: Single, two-stroke
Gearbox: 6-speed
Dry weight: 92.0 kg
Seat height: 958 mm
Power: 15.0 HP (11.0 kW)

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What’s new for the 2026 KTM 125 SX

vs the 2025

Spec	2025	2026
Front suspension	WP XACT-USD, Ø 48 mm	WP XACT-USD (AER), Ø 48 mm
Front brakes	Single disc	Disc brake
Rear brakes	Single disc	Disc brake

Other years 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2025 2026 2027

How it rides

Editorial estimate from the spec sheet - not lab tested

Off-road & trail96%

Cornering90%

City riding10%

Daily riding10%

Touring8%

Two-up5%

Track95%

Best for: Built purely for closed-course motocross racing, it excels at jumps, berms, and rapid direction changes on dirt tracks rather than any street use.
Built for: 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.

Scores are derived from the spec sheet using the same model across every bike, so they compare like for like.

Will it fit you?

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Your height

Inseam (optional)

Units

At 958mm, a rider of 68.9" with a 31" (estimated) inseam will not reach the ground comfortably on the 2026 KTM 125 SX, with a cramped knee angle of around 85 degrees and an upright riding position.

Assumes about 30mm of suspension sag once seated. This is an approximation from category-typical geometry, not a measurement of this bike or of you - sit on one before you buy.

More bikes at over 900 mm — Sky High →

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Full specifications

Engine

Capacity: 124.8 ccm
Power: 15.0 HP (11.0 kW)
Engine type: Single, two-stroke
Power/weight ratio: 0.1630 HP/kg (dry)
Bore x stroke: 54.0 x 54.5 mm
Cooling system: Liquid
Fuel system: Injection
Starting: Electric
Ignition: Vitesco Technologies EMS
Lubrication system: Wet sump

Transmission

Gearbox: 6-speed
Transmission type: Manual
Final drive: Chain
Clutch: Wet multi-disc DS clutch, Brembo hydraulics

Dimensions & weight

Wheelbase: 1493 mm
Seat height: 958 mm
Dry weight: 92.0 kg
Fuel capacity: 7.20 litres
Ground clearance: 359 mm

Chassis & suspension

Frame: Central double-cradle-type 25CrMo4 steel
Front suspension: WP XACT-USD (AER), 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°
Trail: 120 mm

Brakes & wheels

Front brakes: Disc brake
Front brakes diameter: 260 mm
Rear brakes: Disc brake
Rear brakes diameter: 220 mm
Front tyre: 110-17
Rear tyre: 150-17

Specs last verified against published sources: October 2026.

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	2003	2009	2015	2020	2026	2027
Capacity	125 cc	125 cc	125 cc	125 cc	125 cc	125 cc
Dry weight	94 kg	91 kg	91 kg	88 kg	92 kg	92 kg
Seat height	925 mm	985 mm	992 mm	950 mm	958 mm	958 mm
Fuel capacity	7.5 L	8 L	7.5 L	7.5 L	7.2 L	7.2 L