With new features such as more compact dimensions, stronger performance throughout the rev range and a weight reduction of 4 lbs, this newly developed powerplant is the lightest 450 engine on the off-road market. With a reworked single overhead camshaft cylinder head and the latest electronic fuel injection, the 450 XC-F has unrivalled power of more than 62 hp and a highly efficient power delivery.
An all-new camshaft controls intake and exhaust flow through optimized ports in the newly designed cylinder head. This activates four ultra-lightweight titanium valves via extremely rigid rocker arms, which are DLC coated on the intake side. This configuration allows engine speeds of up to 11,500 rpm. In addition, the head is 350 g lighter than the previous model due to the compact design.
Cylinder head and piston
A new 6 mm shorter cylinder is more rigid and matched to the new cylinder head. An extremely lightweight box-in-box type piston together with a weight optimized piston pin contributed to the engine's low vibrations and quick revving character. The compression ratio is 12.75:1.
The 450 XC-F's crankshaft features 10 % more inertia (without increasing weight) and utilizes a shorter connecting rod over the previous model, which contributes to an overall compact and light engine with a snappy power delivery. A higher balancing factor reduces the vibration level. A plain big end bearing with two force-fitted bearing shells runs directly on the crank pin, and the overall design offers the customer lengthened service intervals.
Counter balance shaft
The weight optimized, side-mounted counter balance shaft also time drives the water pump. Thanks to perfect mass balancing and low total oscillating mass, engine vibration is kept to a minimum even at the highest engine speeds.
Like all KTM 4-Stroke motorcycles, the 450 XC-F is started with ease by pushing a button. Demonstrated time and time again, an electric starter can become an invaluable advantage in the heat of off-road competition.
Engine cases and covers
The completely new design of the die-cast engine cases allows for a much more centralized shaft configuration, raising the crankshaft by 7 mm and 9 mm backwards to centralize mass and for a weight savings of 1.2 lbs. Newly designed engine covers made of magnesium feature an advanced surface structure in order to reduce the wear caused by the rider's boots.
The 450 XC-F employs the KTM-developed DDS clutch (Damped Diaphragm Steel) with a wear-free steel basket and extremely heat resistant clutch plates. This design is distinguished by employing a diaphragm spring instead of coil springs, which makes for a considerably easier clutch action. The diaphragm spring also leaves sufficient space for a damping system integrated into the clutch hub, which benefits for both traction and durability.
The new engine of the 450 XC-F uses a lightweight 5-speed gearbox with unchanged gear ratios that are perfectly matched to the power delivery of the large displacement engine. 1st and 5th gears are now treated with a special surface treatment for better reliability.
Engine management system
The completely reworked Keihin Engine Management System, with electronic fuel injection, features an all-new 44 mm throttle body, which provides instantaneous response and maximum performance thanks to a revolutionary injector position. The new ECU (Engine Control Unit) includes a launch control for more efficient starts with the provision of different maps according to the gear sensor selection. In addition, the rider can activate an optional map for a different power delivery via the map select switch on the handlebar.