01. Engine & Exhaust

Engine
Easy to start, well-balanced, torquey and powerful, the 250 cc 4-stroke motor is a compact power factory. Weighting in at only 47.6 pounds, it’s not only lightweight, but packs a punch too, reaching its limits at a monumental 14,000 rpm. It’s safe to say then that the specially-tuned KTM 250 XC-F’s engine is a little titan.


Cylinder head
The centerpiece of the compact DOHC (Double Overhead Camshaft) engine is the new cutting-edge cylinder head. The DLC coated finger followers, as well as the lightweight titanium valves they actuate (intake 32.5 mm, exhaust 26.5 mm), allow for higher engine speeds, a crucial factor in the 250's class-leading performance. In combination with the high-flow ports, it creates a maximized flow rate for an optimal power band and maximum performance, all the way up to a redline of 14,000 rpm.


Crankshaft
The KTM 250 XC-F's crankshaft is located in an ideal position close to the center of gravity, contributing to easier handling. It utilizes a short connecting rod, which makes for an overall compact and lightweight engine with a snappy power delivery. A plain big (bottom) end bearing with two force-fitted bearing shells runs directly on the crank pin. The engine's pressurized lubrication system provides the necessary oil feed for this bearing. This design is a major prerequisite for the extremely high engine speed levels and the unrivalled maximum power of the 250 cm³ engine. Not only that, it enhances the engine's durability, allowing long crankshaft service intervals.


Crankcases and engine covers
The compact engine cases are manufactured using a high pressure die-cast production process which helps with weight reduction, while retaining strength and durability. The design allows for a very centralized shaft configuration, making the engine very short and compact, while contributing to an efficient centralization of mass. Additionally, the engine covers feature a smart surface structure which reduces wear caused by the rider's boots, keeping them looking as fresh as the day you bought it.


Transmission
The KTM 250 XC-F features a robust 6-speed transmission made by PANKL Racing Systems. The gears are made of a strong, forged raw material, ensuring the highest durability and reliability level. There was no need to change the gear ratios that are perfectly matched to the power characteristics of the engine. All four-stroke engines are fitted with a gear sensor, giving the option of different engine characteristics for each gear.


Engine management system
The state-of-the-art Keihin Engine Management System, with electronic fuel injection, features a 44 mm throttle body with separate systems for cold starting and idle adjustment. The throttle cable mount allows for easy access and a smooth routing of the cables. The ECU features selectable engine maps which are optimized to the exhaust, airbox and engine configuration, as well as regulating the unique traction control and launch control which are activated by the handlebar map-select switch. It also provides different maps for each gear, according to the information received from the gear sensor, ensuring maximum power as you shift through the gears.


Cylinder and piston
Inside the short 78 mm bore cylinder, is an extremely lightweight, forged bridged box-type piston made by CP. Its crown geometry is adapted perfectly to the high-compression combustion chamber, where its rigid structure and low weight shine. Thanks to its lightweight construction, the oscillating masses are low, giving the engine extremely lively characteristics.


Balancer shaft
The multifunctional side-mounted counter balance shaft masterfully balances all the oscillating forces, while also driving the water pump. It effectively keeps engine vibrations to a minimum, resulting in the smoothest ride even at the highest engine speeds.


Clutch
The KTM 250 XC-F is fitted with the extremely durable, KTM-developed DS clutch (diaphragm steel), with a wear-free steel basket and heat resistant clutch plates. It uses a diaphragm spring instead of the usual coil springs, which results in considerably easier clutch action. Additionally, the Brembo hydraulic system provides easy and precise clutch modulation throughout the entire operating temperature range.


E-Starter
The standard electric starter on the KTM 250 XC-F uses a proven starter drive and a strong starter motor made by Mitsuba. As demonstrated time and time again, it provides quick and reliable starting, saving you precious time and energy when you need it most.


Cooling
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 250 XC-F features radiators which are mounted close to the center of gravity and match the design of the shrouds perfectly, in order to achieve perfect ergonomics. By using CFD technology (Computational Fluid Dynamics) and a smart coolant circuit routing, the innovative system ensures optimum engine temperature for the highest performance, in all conditions. Above all, the delta distributor, integrated into the frame triangle, features a large center tube, making the coolant flow from the cylinder head to the radiators highly efficient. The radiators have special protectors that protect from flying rocks and debris while also acting as a brace to disperse energy around the radiators in the event of an impact.


Exhaust
When it comes to power delivery and performance, the exhaust on all 4-stroke models plays a key role and packs a punch that is hard to beat. It features a model specific header pipe with an advanced resonator called FDH (Flow Design Header), which is a small chamber around the pipe. The design allows the exhaust to be disassembled without removing the shock absorber and also provides better access to the shock. The aluminum sleeve, end cap and internal design of the silencer allows for slimmer ergonomics, making the bike feel narrower, without compromise to regulatory noise limits.
