Fuel-injected 449 cm³ liquid-cooled, 4-stroke Single delivers hard-hitting power from low- through high-rpm. The broad powerband and responsive throttle offer a broad spread of torquey response that enables racers to get on the gas and go even from down low. Race-inspired tuning and parts like the high-performance bridged-box bottom piston (a mass-production first when introduced on the 2010 KX450F) ensure top-level performance right out of the box. For 2016, an offset cylinder and numerous changes to the intake system offer even more power, a new exhaust system matches local regulations, and a new accessory KX FI Controller enables map calibration without a PC. Like the chassis, the engine benefits from significant weight savings, with the engine group components weighing almost 2 kg less!
Intake valves have a revised head area. The new design, with slimmer throat angle and reduced recess (similar to valves on supersport models) contributes to increased high-rpm performance. Revised air cleaner shape and silencer construction ensure that FIM and MA noise regulations are met.
Excess material was trimmed from transmission gears and shafts results in a weight reduction of approximately 260g.
Aluminium perimeter frame is a narrow across the main beams, considerably lighter, and features revised rigidity contributing to greater front-end feel.
Width across the main frames is approximately 6 mm slimmer than the previous model. This facilitates position changes, making it easier for riders to slide forward and backward.
The lighter weight contributes to the bike’s quicker handling.
Thick walls for the sub-frame (seat rails) offer increased strength. Slim aluminium perimeter frame is a lightweight construction composed of forged, extruded and cast parts. Chassis balance and settings were all set to suit race-experienced riders.
The inward-angled orientation of the radiators (turned in 10 degrees) allows the shrouds to be slimmer than before.
Top of the fuel tank is flat and low, for a very smooth progression from the seat to the tank. The flat design gives the rider greater freedom of movement when changing riding position, and facilitates sitting farther forward.
KX motocrossers have long drawn on works technology to offer riders the best possible performance right out of the box. Launch Control Mode is just one of the factory features that give riders an edge when lining up at the start gate.
The KX450F features a launch control system similar to that on our factory racers. With the simple press of a button, riders can activate a separate engine map designed to ensure efficient race starts in slippery conditions. (The Launch Control Mode map retards ignition timing, allowing tyres to gain grip in low-traction situations, and allowing riders to focus on their lines.)
Type: Liquid-cooled, 4-stroke Single
Displacement: 449 cm³
Bore and Stroke: 96.0 x 62.1 mm
Compression ratio: 12.8:1
Valve system: DOHC, 4 valves
Fuel system: Fuel injection: ø43 mm x 1 (Keihin)
Ignition: Digital DC-CDI
Starting: Primary kick
Lubrication: Forced lubrication, semi-dry sump
Fuel capacity: 6.3 L
Transmission: 5-speed, return
Final drive: Chain
Clutch: Wet multi-disc, manual
Type: Perimeter, aluminium
Front: 80/100-21 51M
Rear: 120/80-19 63M
Front: ø49 mm inverted telescopic SFF-AIR TAC (Separate Function front Fork Air Triple Air Chamber) with adjustable compression damping and rebound damping
Rear: New Uni-Trak with adjustable dual-range (high/low-speed) compression damping, adjustable rebound damping and adjustable preload
Front: Single semi-floating ø270 mm petal disc
Rear: Single ø240 mm petal disc
2017 KX450F Lime Green