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2021 KTM 250 SX [Model Overview]

2021 KTM 250 SX

The 2021 KTM 250 SX: The Fastest In Its Class

The KTM 250 SX is a true competitor, from the rawness of its power to the lightness of its frame. There has been no expense spared about fitting the lightweight frame with one of the most powerful 250cc two-stroke single engines that KTM has made for the 2021 model lineup, which pushes out about 50 HP.

The experienced European manufacturer has definitely done their homework, however. The 250 SX two-stroke is meant to give short, hard bursts of acceleration to gain the speed needed to go flying off a jump or blast out of a corner. Due to the outstanding torsional rigidity of its frame, with a little flex allowed longitudinally, the bike is simply meant to devour any motocross track its front wheel can sniff out.

KTM is balancing the razor’s edge of competition with the 250 SX, making it the fastest, lightest bike in its class, while also pushing engine technology to the limit. The bike comes equipped with WP racing suspension and a 5-speed manual transmission with Brembo hydraulics. As with almost all two-strokes, the bike is kick start only.

The 2021 KTM 250 SX starts at $8,399 USD / $9,399 CAD.

On this page: we’ve curated specs, features, news, photos/videos, etc. so you can read up on the new 2021 KTM 250 SX in one place.

2021 KTM 250 SX

Model Overview

General Info

  • Price: $8,399 USD / $9,399 CAD
  • Key Features:
    • 5-speed manual transmission
    • WP XAct racing suspension with AER tech included
    • Kickstarter

Main Specs

  • Engine Type: 250cc two-stroke single
  • Horsepower: Approx 50 HP
  • Torque: Not provided by manufacturer
  • Wet Weight: 214 lbs (approx 97 kg)
  • Seat Height: Not provided by manufacturer

2021 KTM 250 SX

2021 KTM 250 SX Specifications

From KTM


Engine 250cc, 1-cylinder, 4-stroke engine
Power Approx 50 HP
Bore x Stroke 78 mm x 52.3 mm
EMS Keihin EMS
Power in KW
Starter Kickstarter


Clutch Wet, DDS multi-disc clutch, Brembo hydraulics
Transmission 5-Speed
Chain 5/8 x 1/4″


Suspension Front WP XACT-USD, Ø 48 mm
Suspension Rear WP XACT Monoshock with linkage
Brakes Front 260 mm, Disc brake
Brakes Rear 220 mm, Disc brake
Suspension travel (front) 310 mm
Suspension travel (rear) 300 mm
Tank capacity (approx.) 7 l
Color Black, Orange


Spark Plugs
Headlight LED
Tail Light LED


Overall Length
Overall Width
Overall Height
Ground Clearance 375 mm
Seat Height 950 mm
Wet Weight 95.5 kg



2021 KTM 250 SX

2021 KTM 250 SX Features


The engine of the KTM 250 SX features the latest 2-stroke technology, with a counter-balance shaft for low engine vibration, as well as a reliable hydraulically operated DDS clutch. It has a twin-valve controlled power valve, which contributes massively to making the KTM 250 SX engine the most competitive 2-stroke in its class. Powering through its 5-speed transmission truly is an exhilarating experience.


The cylinder on the KTM 250 SX has a bore of 66.4 mm and is fitted with a Twin-Valve powervalve system. The exhaust port is machined for precise power valve function, providing excellent overall power delivery. By using the two supplied springs, the power characteristics can be changed quickly and easily, ensuring optimal settings for different tracks and rider preference. The lateral cylinder head brackets are made of aluminum and reduce vibration to levels of near insignificance.

Balancer shaft

No more numb hands and feet. This engine design allows for the addition of a lateral balancer shaft, which helps keep engine vibrations to a minimum. This means you can keep charging harder for longer.

Crankcases and engine covers

The compact engine cases are manufactured using a high pressure die-cast production process that helps with weight reduction, while retaining strength and durability. The design allows for optimal shaft arrangements closer to the center of gravity, resulting in perfect mass centralization and easier rideability. The engine covers feature a smart surface structure that reduces wear caused by the rider’s boots, keeping them looking as fresh as the day you bought it.


The engine has a strong 5-speed gearbox built to suit any kind of motocross track. The gear ratios were developed specifically to match the power delivery of the 250 cc engine. The gearbox also features a “no-dirt” gear shifter. Similar to the foot peg design, it prevents the build-up of dirt and ensures the next gear is always available, no matter what the conditions.


The frame is professionally crafted from hydroformed chromium molybdenum steel tubes that are robot welded, ensuring the highest levels of consistent quality. The stiffness has been precisely tailored for the most dynamic handling, and works in perfect harmony with the suspension to provide nimble agility without losing high-speed stability. The frame also features “no dirt” footpegs, which have a simple but effective self-cleaning system that ensures the footpegs return to their original position, providing complete control in all conditions. All SX frames feature the same highly durable powder coating as the KTM Factory machines and come with standard frame protectors. The subframe is made from lightweight aluminum, providing rear fender stability and strong support for the rider at little extra weight.


The one-piece swingarm is manufactured using a gravity die-cast production process for exceptional strength at the lowest possible weight. It offers a wide range of adjustment for the rear wheel, allowing for a shorter wheelbase on tighter, twisty tracks, or a longer wheelbase for greater stability on longer, more choppy tracks. The swingarm’s chain measurement markings are visible from above, making adjustment simpler and more accurate.


All KTM SX models feature a seat that perfectly matches the range’s dynamic performance-oriented ergonomics. The seat cover features silicone strips that provide better feel and grip for the rider. The seat is conveniently fixed to the bike using one long, lateral screw, making it secure and easy to handle.


All full-size KTM SX models are equipped with the same high-strength aluminum tapered handlebar, made by NEKEN. The handlebar is fixed in rubber damped mountings, which allow for two different positions. The handlebars come standard with an ODI vulcanized grip on the right side and a comfortable ODI lock-on grip, which does not require any wire or glue, on the left. They also feature a bar-pad with a cover that can be attached and removed with little effort.

2021 KTM 250 SX Photos

2021 KTM 250 SX Videos