The completely new 450 SX-F engine design is more compact, lighter and is said to provide higher performance throughout the entire range of power. You can see how much narrower the new engine is compared to the ghosted image of the older powerplant in the image above. An all-new cam activates the four ti valves via extremely rigid rocker arms which are DLC coated on the intake side for engine speeds up to 11,500 RPM. The compression ratio on this one is 12.6:1.
The crankshaft position was moved 7mm higher and 9mm to the rear to help centralize mass, and overall, the engine is 23mm shorter, 9mm lower, and 23mm narrower than before. it also gets the new lateral head stay brackets.
The 450 uses the same new Keihin 44mm throttle body as the 250, with no links, which allow for a new throttle cable system, and adjusters that are up next to the new throttle housing.
The 450 also uses the new ECU, and Launch Control setup as the 250. (Check the previous page for more detail.)
There is new cylinder head combustion chamber geometry, optimized ports, a shorter timing chain, and friction reduced chain guides for improved power and reduced weight.
New 6mm shorter cylinder, lightweight piston connected to a shorter connecting rod and a crankshaft with 10% more inertia contribute to the compact design, light engine feel and plenty of power.
The new five-speed transmission is 8mm narrower, and features a new surface treatment on first and fifth gears along with a special low friction coating on the shift forks to provide precise and easy shifting.
DDS (Damped Diaphragm Steel) clutch has a new lighter basket along with a reworked inner hub and pressure plate providing better oil supply and improved cooling of the clutch. As always, it's operated by a hydraulic Brembo mechanism.
The 450 FE also gets the new starter and lightweight Lithium-Ion starter battery that helps trim weight from the electric start system. It also scores the new WP radiators and new louvers that were covered in the 250 info.
There's also a new Flow Design Header (FDH) with an integrated sound resonator that's also designed to increase power along with a new lightweight silencer that is 40mm shorter than the previous design.
Other new details include the simplified wiring harness that allow the mechanic to remove the subframe without compromising the electronics. There's also the new engine covers feature an advanced surface design that provides reduced surface wear caused by the rider’s boots, and a four pound lighter overall weight for the engine.
