CRANKSHAFT

The crankshaft on the new 250 EXC‑F has 5% more gyrating mass available for achieving optimum traction. Similarly to last season's KTM SX-F models, it is equipped with a plain bearing in the lower conrod eye. The previous needle bearing is replaced with two press-fit bearing shells that run directly on the crankshaft's crank pin. The engine's direct pressure lubrication system ensures the necessary oil supply. This design enhances the durability of the engine, thereby enabling an extension to the service intervals for the crankshaft - a benefit in terms of time and costs.

ENGINE CASE

Thanks to a completely new design of engine case, which is now manufactured in a pressure die-casting process, it has been possible to significantly reduce the wall thicknesses compared with a gravity die-cast case. A new, high-strength, aluminium alloy ensures that the case is resistant to stone impact and other damage.

BALANCER SHAFT

To counterbalance the inertia forces, the new 250 EXC‑F engine is now also equipped with a balancer shaft that acts as a multi-function shaft, driving timing chain and water pump simultaneously.

NEW ENGINE

The 250 EXC‑F is virtually a guarantor for top places in hard-fought enduro battles – this is substantiated not only by the numerous world titles. For the 2014 model year, KTM engineers have ignited the next evolutionary stage and developed a completely new, state-of-the-art DOHC engine that unites the concentrated engine expertise amassed from motorsport and development. The design of the new generation shares numerous basic components with the successful 350 EXC‑F engine. This results in a perceptible increase in torque, above all in the low to mid rev range (an additional 4 Nm between 6,000 and 7,000 rpm).

CYLINDER HEAD

The heart of the newly developed DOHC engine is the redesigned cylinder head with twin overhead camshafts and DLC-coated cam followers. Compared with the previous year, larger, flow-optimised ducts in conjunction with the more generously dimensioned intake valves guarantee 10% more gas flow and therefore significantly improved performance. The new camshafts have also been designed to achieve a perceptible increase in torque compared to the predecessor model, together with enduro-specific engine characteristics. The engine's optimised water jacket ensures even better heat dissipation.

STARTER

The new 250 EXC‑F engine can be started with either a kickstarter or an electric starter. Positioned behind the cylinder, the electric starter is well protected and connected via the electric starter drive in the ignition cover to the further improved freewheel on the ignition rotor. The starter freewheel has been optimised for increased durability and reliability.

DDS CLUTCH

The new 250 EXC‑F is also equipped with the further optimised DDS (Damped Diaphragm Steel) clutch, which features a wear-free outer clutch hub and diaphragm springs. The single-piece hub is machined along with its primary gear from a solid block of high-strength steel. This process guarantees unbeatable reliability and allows the engine to be extremely narrow thanks to the compact, rivetless design of the outer clutch hub. In addition, this design allows use of thin steel discs, which also contributes to the compact dimensions of the clutch. The diaphragm spring enables implementation of an additional hub damping mechanism - a benefit in terms of traction and gearbox wear. Furthermore, an optimised inner clutch hub improves the durability of the clutch. Finally, in conjunction with the diaphragm spring, the hydraulic clutch actuation system from Brembo ensures very smooth and very precise clutch control.

TRANSMISSION

Compared with its predecessor, the new six-speed enduro gearbox, developed especially for the 250 EXC‑F, has slightly shorter transmission ratios for 4th, 5th and 6th gears. The new gearbox excels with high precision and easy shifting. The secondary transmission has also been adapted to the new gearbox.

ENGINE MANAGEMENT SYSTEM (EMS)

The engine management system from Keihin, with electronic fuel injection and 42 mm throttle body, ensures spontaneous responsiveness and maximum engine performance. An oil-cooled, 196 W alternator provides sufficient power for the fuel injection system, lights and other electrical loads. A redesigned ECU ensures even faster and absolutely reliable data processing. Various engine characteristics can be selected via the EMS, with a map-select switch available as a PowerPart. Furthermore, a user-setting tool (also available as an option) allows data to be read from the bike by laptop and the mapping, ignition and fuel injection to be modified in a matter of a few mouse clicks.