2021 KTM 125 SX Base

2021 KTM 125 SX

The KTM 125 SX is the most compact and lightweight of the full-size bikes and delivers a confidence-inspiring ride like no other. A lightweight chassis teams up with the most competitive 125 cc 2-stroke engine in its class, delivering superior agility and power to fulfil the demands of any young adrenaline seeker. This 2-stroke screamer is the ultimate entry point into the pro ranks and a sure-fire way to add to the trophy collection.

ENGINE & EXHAUST

• ENGINE

The KTM 125 SX engine is undoubtedly once again the most competitive and powerful engine in its class. With an outstanding power-to-weight ratio, low cost and overall simplicity, it is clear that 2-strokes will continue to have a successful future at KTM. The compact and durable 37.9 lbs engine was developed using the latest KTM engineering know-how, resulting in broad power across the rev range. Its easy rideability and outstanding performance are benefits that equate to faster lap times and better results.

• CYLINDER

At the heart of the 125 cc engine is a reworked cylinder with a 54 mm bore. It features an improved power valve unit with a sophisticated mechanism designed for the lateral support exhaust ports. The new exhaust port layout increases engine performance, while the upper contour of the exhaust port has been machined to ensure more accurate port timing. Together with the two-component cylinder head, the newly reworked cylinder is key to the KTM 125 SX's outstanding performance across the entire rev range.

CHASSIS

• FRAME

The frame and subframe on the KTM 125 SX caters for the aggressive riding styles associated with 125 cc racing. The frame itself 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

• SWINGARM

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.

ERGONOMICS & COMFORT

• SEAT

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.