Motocross Bikes

2015KTM 125 SX

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The 2015 KTM 125 SX is a lightweight two-stroke motocross bike designed for junior and amateur riders seeking an affordable entry into competitive off-road racing. Known for its nimble handling, responsive power delivery, and proven WP suspension, it delivers the authentic KTM dirt bike experience in an accessible package. Its compact dimensions and manageable weight make it ideal for developing fundamental riding skills on the track.

Capacity: 124.8 ccm
Engine: Single, two-stroke
Gearbox: 6-speed
Dry weight: 90.8 kg
Seat height: 992 mm
Power: 15.0 HP (11.0 kW)

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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 992mm, a rider of 68.9" with a 31" (estimated) inseam will not reach the ground comfortably on the 2015 KTM 125 SX, with a moderate knee angle of around 90 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: 0.1652 HP/kg (dry)
Bore x stroke: 54.0 x 54.5 mm
Cooling system: Liquid
Fuel system: Carburettor
Starting: Kick
Ignition: Contactless, controlled, fully electronic ignition system with digital ignition timing adjustment, type Kokusan
Lubrication system: Mixture oil lubrication 1:40

Transmission

Gearbox: 6-speed
Transmission type: Manual
Final drive: Chain
Clutch: Wet multi-disc clutch, hydraulically operated

Dimensions & weight

Wheelbase: 1480 mm
Seat height: 992 mm
Dry weight: 90.8 kg
Fuel capacity: 7.50 litres
Ground clearance: 395 mm

Chassis & suspension

Frame: Central tube frame made of chrome molybdenum steel tubing
Front suspension: WP Suspension Up Side Down 4860 MXMA CC
Rear suspension: WP Suspension 5018 BAVP DCC
Front wheel travel: 300 mm
Rear wheel travel: 317 mm
Rake (fork angle): 26.5°
Trail: 120 mm

Brakes & wheels

Front brakes: Single disc. Brake calipers on floating bearings
Front brakes diameter: 260 mm
Rear brakes: Single disc. Brake calipers on floating bearings
Rear brakes diameter: 220 mm
Front tyre: 80/100-21
Rear tyre: 100/90-19

Other

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