Motocross Bikes

2005KTM 125 SX

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The 2005 KTM 125 SX is a lightweight motocross machine designed for young riders and beginners entering competitive off-road racing. Powered by a liquid-cooled 125cc two-stroke single-cylinder engine with a five-speed gearbox, it delivers responsive performance and agility on the track. Known for its reliable construction and user-friendly handling characteristics, the 125 SX remains a popular choice for developing fundamental riding skills in motocross.

Capacity: 124.8 ccm
Engine: Single, two-stroke
Gearbox: 6-speed
Dry weight: 92.4 kg
Seat height: 925 mm
Power: 15.0 HP (11.0 kW)

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What’s new for the 2005 KTM 125 SX

vs the 2004

Spec	2004	2005
Dry weight	93.6 kg (206.4 pounds)	92.4 kg (203.7 pounds)
Front suspension	WP-USD 48/26 MA/PA	WP-USD 48 mm (1.89 inch.)

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 925mm, a rider of 68.9" with a 31" (estimated) inseam will not reach the ground comfortably on the 2005 KTM 125 SX, with a cramped knee angle of around 80 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: 0.1623 HP/kg (dry)
Bore x stroke: 54.0 x 54.5 mm
Cooling system: Liquid
Fuel system: Carburettor
Starting: Kick
Ignition: Kokusan digital 2K-1
Lubrication system: Mixture oil lubrication 1:40

Transmission

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

Dimensions & weight

Wheelbase: 1471 mm
Seat height: 925 mm
Dry weight: 92.4 kg
Fuel capacity: 7.50 litres
Ground clearance: 390 mm

Chassis & suspension

Frame: Chromium molybdenum
Front suspension: WP-USD 48 mm (1.89 inch.)
Rear suspension: WP-PDS-DA shock absorber
Front wheel travel: 300 mm
Rear wheel travel: 335 mm
Rake (fork angle): 27.0°
Trail: 120 mm

Brakes & wheels

Front brakes: Single disc
Front brakes diameter: 216 mm
Rear brakes: Single disc
Rear brakes diameter: 260 mm
Front tyre: 80/100-21
Rear tyre: 100/90-19

Specs last verified against published sources: September 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	2005	2009	2015	2020	2027
Capacity	125 cc	125 cc	125 cc	125 cc	125 cc	125 cc
Dry weight	94 kg	92 kg	91 kg	91 kg	88 kg	92 kg
Seat height	925 mm	925 mm	985 mm	992 mm	950 mm	958 mm
Fuel capacity	7.5 L	7.5 L	8 L	7.5 L	7.5 L	7.2 L