The KX450F’s 449cc DOHC, four-stroke Single boasts new engine cases that are thinner yet lighter than the previous cases. Its cylinder has been moved forward 8.5mm, its intake ports have been revised, its crankshaft has been lightened, its piston is all-new, and it boasts a more compact 43mm Keihin throttle body among other revisions.

Single cylinder, four-stroke 27.4 cu-in 449 cm3 5-speed 238 lbs / 108.8 kg

New from the cases up last year, the KX’s compact, 449cc, fuel-injected, DOHC single features the same 96 x 62.1mm bore and stroke and 12.8:1 compression ratio. It also sports the same cylinder head, bridged-box piston and cam specs as the 2016 model, and its cylinder is offset 8.5mm on the cases to help reduce drag on the cylinder wall.

Displacement 449.0 ccm (27.40 cubic inches) Engine type Single cylinder, four-stroke Compression 12.8:1 Bore x stroke 96.0 x 62.1 mm (3.8 x 2.4 inches)