01. Engine & Exhaust

Engine
Featuring one of the most competitive and powerful engines in the 125 cc class, the KTM 125 XC is also equipped with an elextric starter. 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 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 better race results.


Cylinder
At the heart of the 125 cc engine is a 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 exhaust port layout increases engine performance, while the upper contour of the exhaust port has been machined to ensure more accurate port timing. The two component cylinder head works in complete harmony with the cylinder to deliver outstanding performance across the entire rev range.


Crankcases and engine covers
The lightweight engine cases are manufactured using a high pressure die-cast production process, keeping wall thickness to a minimum while retaining strength and durability. The design allows for a high crankshaft position which is located near to the center of gravity, resulting in optimal mass centralization and easier rideability. The engine body is extremely compact, which contributes significantly to the low engine weight.


Transmission
The 6-speed transmission works perfectly for cross-country duty and provides precise and easy shifting. An advanced ´No Dirt´ gear shift lever design prevents muck from blocking the joint. Because even dirt lovers hate mud when it’s in the wrong places.


Carburetor
The KTM 125 XC is fitted with a MIKUNI TMX 38 mm flat slide carburetor. Featuring latest technology reed blocks for the intake it offers optimal function, sealing and reliability, ensuring the whole system is always providing smooth and controllable power throughout the rev range.


Cooling
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 125 XC features radiators which are mounted low. This lowers the center of gravity and matches the design of the new shrouds perfectly in order to achieve perfect ergonomics. By using CFD technology (computational fluid dynamics) together with a clever coolant circuit routing, the innovative system ensures the optimum engine temperature for the highest performance, no matter what the conditions. The radiators also feature special protectors that serve not only as protection from flying rocks and debris but also as a brace that disperses energy around the radiators in the event of an impact.


Exhaust
When it comes to power delivery and performance, the exhaust developed specifically for this bike plays a key role and packs a punch that is hard to beat. In addition, its special shape provides slimmer ergonomics while still operating safely within the noise limits for racing.
