01. Engine & Exhaust
The 450 cc engine is the ultimate powerhouse when it comes to KTM's competitive motocross range. Its compact, lightweight design features a single overhead camshaft cylinder head, fueled by a highly advanced electronic injection system. This enables the impressive power to be distributed extremely efficiently throughout the rev range. Even with its super-beneficial electric starter, this model is still the lightest 450 cc engine on the MX market.
The KTM 450 SX-F is fitted with a lightweight, compact SOHC (single overhead camshaft) cylinder head. The design focusses on mass centralization, contributing to overall handling excellence. The overhead camshaft has a friction-optimized surface and valve timing that delivers impressive responsiveness. The four ultra-lightweight titanium valves (intake 40 mm, exhaust 33 mm) are activated via extremely rigid rocker arms. The rockers on intake side are DLC coated, allowing for impressive engine speeds up to 11,500 rpm. Low-friction chain guides further support the high RPM levels. The innovative head configuration guarantees the most efficient delivery of the unrivalled power, keeping a strong edge over the competition.
The crankshaft on the KTM 450 SX-F is located in an ideal position close to the center of gravity, contributing to better mass centralization. It utilizes a short connecting rod, which allows for a compact motor design and a snappier power delivery. The whole unit is extremely well-balanced, with the perfect amount of inertia for optimal traction and ride-ability. A plain big end bearing with two force-fitted bearing shells, runs directly on the crank pin, with the necessary oil feed for this bearing supplied by the engine's pressure lubrication. This design also enhances durability, allowing for long crankshaft service intervals - resulting in less effort and cost and more time spent on two wheels.
Crankcases and engine covers
The compact engine cases are manufactured using a high pressure die-cast production process that helps with weight reduction, while retaining strength and durability. The design allows for optimal shaft arrangements close to the center of gravity, resulting in better mass centralization and easier ride-ability. The engine covers feature a smart surface structure that reduces wear caused by the rider's boots, keeping them looking as fresh as the day you bought it.
The transmission on the KTM 450 SX-F FACTORY EDITION is focused on lightweight performance without compromise to durability. There was no need to change the gear ratios as they have been perfectly matched to the power delivery of the large displacement engine. The secondary drive (sprockets) ratio also remains unchanged (13/49). All four-stroke engines are fitted with a gear sensor, which provides the option of different engine characteristics for each gear, depending on engine load. An advanced "no-dirt" gear lever design prevents dirt from building up and together with the reliable gearbox, guarantees that the next gear is always an easy click away.
Engine management system
The state-of-the-art KEIHIN Engine Management System, with electronic fuel injection, features a 44 mm throttle body. The injector position guarantees optimal atomization of the fuel and air on the way to the combustion chamber, resulting in instant response and maximum performance when opening the throttle. There are also separate systems for cold starting and idle adjustment. The ECU features maps which have been developed to precisely match the exhaust and cylinder head, with options for regulating traction and launch control. 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 95mm bore cylinder, thumps a new forged box in box piston with a hard anodized compression ring groove and an optimized profile. Its crown geometry is adapted perfectly to the high-compression combustion chamber, where its rigid structure and low weight really shine. Thanks to the low oscillating masses, the engine is as snappy as it is strong.
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.
The 450 SX-F FACTORY EDITION features a DDS (Dampened Diaphragm Steel) Clutch that is actuated hydraulically by a Brembo master and slave cylinder. The single diaphragm steel pressure plate offers better feel and function than a traditional multiple coil spring set-up. The damping system provides better traction and reliability while the CNC-machined basket allows for thin steel liners for a compact design. A special replica Hinson billet clutch cover is fitted to the FACTORY EDITION.
The standard electric starter on the KTM 450 SX-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.
Handlebar map select switch
Within easy reach of the left grip on all four-stroke models, is a multifunctional handlebar map switch, which features the innovative control functions; traction control; launch control and alternative power curves (standard <-> advanced). The TRACTION CONTROL is a unique feature that guarantees more efficient traction and better control when accelerating the bike, especially in challenging track conditions. It can be activated on the handlebar map switch while riding. With a simple push of the two buttons at idle speed, the rider can also activate LAUNCH CONTROL, ensuring the most effective launch out of the gate. The map switch also gives the rider the chance to select an alternative power map besides the standard configuration, providing him with options during the race.
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 450 SX-F features radiators which are positioned for a lower the center of gravity. Their design matches the shrouds perfectly and offers a great slim feel to the 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 don't only serve as protection from flying rocks and debris but also as a brace that disperses energy around the radiators in the event of an impact.
The header pipe features a flow-designed resonance chamber that is seamlessly integrated into the system for low noise and optimal power delivery. The lightweight slip-on AKRAPOVIČ muffler delivers excellent performance , while ensuring noise levels comply with competition requirements.