Anybody that has ever ridden a motocross bike understands the thrill of it all. Those that have taken it a step further and competed in motocross understand that there’s nothing like it.

That’s why, if you’re part of the latter and you want to race in the Junior World Championship, you need not look further than the KTM 125 SX. Designed with slim bodywork emphasized by a slim seat and spoiler lines, the 125 SX is the kind of bike that young riders can go to battle with.

What’s better, the free-revving and lively 125cc two-stroke engine has gained even more performance for the current season, something that seems highly improbable given the impressive credentials of its predecessor.

But the thing that makes the 150 SX such a special motocross bike is that KTM has built a completely new frame and a new, progressive linkage rear suspension. Apart from the new linkage rear suspension, there is the new cast aluminum swingarm, which has been designed for minimum weight and supplies optimum lateral stiffness and defined longitudinal flexibility. This is a major contribution to the 150 SX’s excellent tracking stability, playful handling, and extreme traction.

The further improved upside-down telescopic fork incorporating closed-cartridge technology now ensures even greater punch with a somewhat tauter setting. At the same time, the WP fork with 48 mm (1.89 in) outer tube diameter bolsters the playful handling of the 150 SX to levels that are championship worthy.

If somebody asked you what junior motocross bike you’d like to have on your side in the strongest of competitions, you won’t find anything better than the 150 SX.

Find out more about the KTM 150 SX after the jump.

  • 2012 KTM 150 SX
  • Year:
  • Make:
  • Model:
  • Engine:
    Single cylinder, 2-stroke
  • Transmission:
    6 gear, claw shifted
  • Energy:
    Keihin PWK 38S AG
  • Displacement:
    143.6 L
  • Price:


2012 KTM 150 SX Exterior Drivetrain
- image 435010

The 150 SX’s flow-optimized intake flange between airbox and carburetor now ensures even better charging with fresh gas. This results in even freer revving and even more power in all rev ranges for the liquid-cooled, two-stroke machine.

New Exhaust Expansion Chamber

The 150 SX’s new exhaust expansion chamber has not only improved in quality; in conjunction with the two-stroke machine’s exhaust control system, its optimized soundbox ensures an extra shot of engine power - explosive, but dependable.


2012 KTM 150 SX High Resolution Exterior
- image 435008

The 150 SX’s bodywork with the very slim seat and spoiler lines, plus excellent contact points, perfects the bike’s ergonomics, making handling even simpler and more precise.

New Frame and Suspension

2012 KTM 150 SX High Resolution Exterior
- image 435005

The 150 SX’s completely revamped frame made from high-quality chrome-molybdenum steel is not only extremely light and torsion-resistant. It is also characterized by a particularly balanced geometry that combines playful handling with razor-sharp precision.

The two-strokes in the MX range from KTM are now also equipped with the elaborate linkage rear suspension system. Linking the shock absorber via a lever system provides high progressiveness and wide adjustment ranges. The 150 SX therefore feels at home, even on the most brutal motocross courses.


2012 KTM 150 SX High Resolution Exterior
- image 435012
Design 1-cylinder 2-stroke engine, water-cooled, with reed intake and exhaust control
Displacement 143.6 cm³ (8.763 cu in)
Bore 56 mm (2.2 in)
Stroke 58.4 mm (2.299 in)
Starting aid Kickstarter
Transmission 6 gear, claw shifted
Primary gear 23:73
Final drive 14:50
Clutch Wet multi-disc clutch / hydraulically operated
Ignition system Contactless, controlled, fully electronic ignition system with digital ignition timing adjustment, type Kokusan
Frame Central tube frame made of chrome molybdenum steel tubing
Forks WP Suspension Up Side Down 4860 MXMA CC
Shock absorber WP Suspension 5018 BAVP DCC
Suspension travel Front 300 mm (11.81 in)
Suspension travel Rear 330 mm (12.99 in)
Brake system Disc brakes, brake calipers on floating bearings
Brake discs - diameter Front 260 mm (10.24 in)
Brake discs - diameter Rear 220 mm (8.66 in)
Chain 5/8 x 1/4"
Steering head angle 63.5°
Wheel base 1,480±10 mm (58.27±0.39 in)
Ground clearance (unloaded) 395 mm (15.55 in)
Seat height (unloaded) 992 mm (39.06 in)
Total fuel tank capacity approx. 7.5 l (1.98 US gal)
Unleaded premium fuel, mixed with 2-stroke engine oil (1:40)
Weight without fuel approx. 91.6 kg (201.9 lb.)


Motorcycle-USA----"The engine power of the KTM 150 SX is closer to that of the 250 that the 125 and has better performance than it did before. It has top ergonomics with a perfect contact points for nicer handling. This is a hardy machine that is very well equipped with just about everything you need."

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