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150 SX - 2019


Model Description

Never-ending fun has a name – KTM 150 SX. This is a bike that combines the light handling of a 125 with so much power and torque that it puts many a 4-stroke 250 in the shade – the ideal weapon for all 2-stroke fans. For model year 2019, KTM has grafted the light, compact and strongest engine in its class onto a completely new chassis. The result is an absolutely unbeatable overall package that turns the KTM 150 SX into the ultimate machine capable of taking on all comers on the track.
For model year 2019, KTM has given the KTM 150 SX and exhaust system with a new header and new silencer. The increased engine power is due, among other things, to the header with an optimized shape using the latest 3D stamping technology and new silencer internals. A welded aluminum bracket replaces the previous plastic collars used to secure the silencer and also helps to bring down the weight.

The reliable 6-speed transmission for the new model year boasts a variety of improvements. It is an extremely high-quality unit and is now made by Pankl from Austria. The gear ratios have been taken over from its predecessor and are matched optimally to the requirements of the 150 engine. KTM's advanced No-Dirt technology is used for the gear shift lever to prevent mud and dirt from fouling the lever joint and thus guarantees reliable gear changing at all times.

The newly developed DS (diaphragm steel) clutch has a one-piece outer clutch hub and a primary gear made of high strength billet steel. This guarantees unbeatable reliability and, due to its compact, rivetless construction, reduces the engine width by 10 mm. Incorporating steel carrier friction discs, the extremely heat-resistant clutch plates ensure reliable disengagement of the clutch. They are pre-tensioned by means of a specially designed diaphragm spring, which significantly reduces the force required to pull the clutch lever. The Brembo hydraulic system also ensures an easy and precise clutch action.
The engine of the KTM 150 SX, which was developed using the most advanced expertise and state-of-the-art technology, delivers power that is second to none in its class – and it does that over the entire rpm range. The rider benefits with excellent rideability that delivers amazingly fast lap times. It shares its key components with the best-in-class KTM 125 SX. This means that by simply mounting the cylinder, cylinder head and piston onto a 125cc stock engine it can be turned into a KTM 150 SX engine, without having to replace the crankshaft.
In order to centralize the masses more effectively, the crankshaft is positioned high up and close to the center of gravity, which also has a positive effect on rideability. The extremely compact die-cast crankcase brings down the overall weight of what is already a light bike. KTM has also reinforced the seat of the kick-starter intermediate gear for the new model year to improve reliability. With a new clutch, the new clutch cover is now lower, which has reduced the engine width by 10 mm.
At the core of the engine is a compact cylinder with a 58 mm bore. Compared to the predecessor models they feature a reworked exhaust port which is now CNC milled for a more precise timing and improved interaction with the main power valve, which is made of a new raw part and machined too. Together with a twin-component cylinder head, this has resulted in outstanding engine performance and throughout the entire rpm range.

Fitted with a 38 mm flat slide MIKUNI carburetor, the KTM 150 SX engine provides both a smooth and controllable power delivery over the entire rpm range and offers precise throttle response. It has been matched perfectly to the new air filter box and the new exhaust system.

Model Specification


Engine Type

Single cylinder, 2-stroke


143.9 cc




6 gears

Engine Lubrication

Mixture oil lubrication


Liquid cooled


Wet multi-disc clutch, Brembo hydraulics





Central double-cradle type


5/8 x 1/4

Steering Head Angle

63.9 degrees

Tank Capacity

7.5 litres


Primary Gear Ratio


Secondary Gear Ratio


Brake System Front

Disc brake 260 mm

Brake System Rear

Disc brake 220 mm


Front Suspension

WP-USD, AER airfork 48 mm

Rear Suspension

WP shock absorber with linkage

Suspension Travel Front

310 mm

Suspension Travel Rear

300 mm



58 mm


54.5 mm


1485 mm

Ground Clearance (unloaded)

375 mm

Seat Height

950 mm

Weight (No Fuel)

87.5 kg