01. Engine & Exhaust

Engine
Combining compact dimension with an immense power output, the KTM 450 XC-F´s fuel-injected SOHC engine is the most powerful and refined 450 cc on the market. Its class-leading power delivery is available throughout the entire rev range and with a reduced weight of only 29.2 kg, this engine is the most compact, lightest and most competitive powerplant out there.


Cylinder head
The KTM 450 XC-F engine is fitted with a compact SOHC cylinder head for optimal mass centralization while contributing to even better handling. The head configuration promises efficient power delivery and unrivalled performance as the gas flow through the ports is controlled by a single overhead camshaft. It features a durable axial fixation of the de-compressor shaft and an efficient, integrated engine breather system. The rocker arms and low-friction timing chain guides guarantee a consistent performance throughout the rpm range.


Crankshaft
The KTM 450 XC-F’s crankshaft 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 necessary oil feed for this bearing is ensured by the engine’s pressurized lubrication. This design is a decisive benefit in terms of the crankshaft service interval, which can be lengthened due to the plain bearing. So just pin it, all day long.


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 450 XC-F uses a lightweight 5-speed transmission with gear ratios that are perfectly matched to the power delivery of its large displacement engine. The 1st and 3rd gears are treated with a special surface coating for better reliability. An advanced ´No Dirt´ gear shift lever design prevents mud and sand from blocking the joint of the lever and guarantees trouble-free shifting. All 4-stroke engines are fitted with a gear position 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 95 mm bore cylinder, is an extremely lightweight, box-in-box type piston made by König. In conjunction with the light but extremely durable piston pin, it is a major contributor to the engine's high performance, low vibrations and engine-speed. The compression ratio of 12.75:1 delivers exceptional engine performance and reduces the risk of engine knocking. Additionally, the top of the piston is optimized for a highly efficient combustion.


Balancer shaft
The side-mounted balancer shaft does double duty also driving the water pump. Thanks to its perfect balance and low oscillating masses, engine vibration is kept to a minimum.


Clutch
The KTM 450 XC-F employs the KTM-developed DDS clutch (damped diaphragm steel) with a robust steel basket, extremely heat resistant clutch plates and new, nitrated steel liners reducing the wear. This clever design employs a diaphragm spring instead of the usual coil springs, making for considerably easier clutch action. A diaphragm spring also leaves sufficient space for a damping system to be integrated into the clutch hub. The goal is traction, but durability is as well. Light operation and telepathic amounts of control are standard with this hydraulic Brembo actuated clutch.


E-Starter
Like all KTM 4-stroke motorcycles, the KTM 450 SX-F is started at the push of a button - a priceless advantage when you’re on the clock.


Cooling
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 450 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.
