The KX450F features a number of engine refinements, including the first mass-production use of a high-performance bridged-box bottom piston that offers more power in the high and over-rev rpm ranges. Revised cam timing and ECU settings provide better mid-high rpm performance, while reinforcements to the cylinder sleeve and right side crankcase increase durability.
The race-ready engine is compact and light, with a short 100mm cylinder head and a 12.5:1 compression ratio. A wedge-shaped crank web offsets 60% of the crankshaft’s reciprocating weight, producing an effective “counterweight” effect. This is on par with Kawasaki’s factory racers and helps reduce engine vibration, smooth power delivery and enhance low-rpm throttle response. A new 40mm shorter stainless steel exhaust pipe connects to a large-volume silencer which uses long-fiber packing material to maximize service intervals. A new rubber damping collar in the rear silencer mount provides a boost to long-term durability.
The KX450F’s Digital Fuel Injection (DFI) automatically adjusts to suit track and climate conditions, and offers stable fuel-metering, even when landing from jumps in tough motocross conditions. The DFI system includes a compact and lightweight ECU, a 43 mm throttle body, a lightweight aluminum in-tank fuel pump and an ultra-fine atomizing injector. Set at a 45° angle for ideal mid-range power, the 12-hole injector sprays precise, 60-micron fuel particles for smooth power delivery and accurate engine response throughout the rpm range.
Designed specifically for motocross, the KX450F’s lightweight DFI system doesn’t require a battery; the engine can be started within three rotations of the crankshaft, using only the electricity generated through the initial stroke of the kickstarter. A new ECU program with revised settings offers improved engine response at low-mid rpm.
An optional ECU Setting Tool allows racers to select from several different ECU data maps, or fine-tune a custom map that alters fuel injection and ignition timing to suit different tracks and conditions. The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant temp, air temp, ignition timing, fuel adjustments, gear position and system voltage.
The engine’s phenomenal power is delivered through a new clutch that features a lighter operating plate with improved oil drainage and new friction plates with 75% more friction material than last year’s unit. The entire assembly is designed to provide improved clutch feel and enhanced durability. A new final drive chain features thinner inner links and a 20 gram weight savings to help boost acceleration.
Chassis updates focus on making the KX450F even easier to ride fast. A new steering stem shaft and revised suspension tuning provide lighter handling, improved suspension action, increased comfort and greater cushioning when landing from jumps.
The 2010 KX450F’s D-shaped aluminum swingarm features a revised cross section with narrower ribs and thinner walls. It pivots high in the aluminum frame to maximize rear wheel traction. Mounting the arm of the Uni-Trak® rear suspension linkage below the swingarm provides a long rear suspension stroke and facilitates precise shock tuning.
Complementing the responsive chassis with settings optimized for experienced racers, the KX450F’s suspension offers a host of features for precise cornering and sharp handling. For 2010, the Kayaba Air-Oil-Separate (AOS) fork receives revised spring rate and damping settings working in conjunction with a less rigid steering stem to offer improved action and increased comfort during the initial phase of the suspension stroke. The fork features a Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes to minimize stiction when the fork is exposed to lateral forces that would otherwise hamper slide action. The result is smooth and precise fork response, especially during cornering. The overall suspension action is extremely smooth due to a friction-reducing Kashima Coat treatment on the inside surfaces of the outer fork tubes and the rear shock reservoir. Black wrap-around guards provide excellent protection for the fork sliders.
The 2010 KX450F’s Kayaba rear shock received new spring rate and damping settings which contribute to increased stability and improved impact performance when landing jumps. It features a large 50mm piston and a Kashima Coat treatment on the shock internals to help maintain a plush feel throughout the toughest motos. Easily accessible dual compression adjusters allow high- and low-speed damping to be tuned separately, giving mechanics and riders the ability to easily fine-tune the suspension for difficult track conditions.
New 10mm-thicker and 7.6mm-wider radiators feature increased fin and tube pitch for increased strength and better resistance to mud build-up. The extra strength of the new radiators allowed the reinforcing brackets to be eliminated, resulting in lower overall weight. New one-piece, dual injected, two-tone green and black plastic shrouds accommodate larger new radiators while still providing slim ergonomics.
A slim seat design with firm urethane foam, a non-slip top surface and smooth sides provides good seated grip and excellent rider mobility. The frame echoes the slim profile at the top, but widens at the lower end by the ankles to provide the rider with better feel and control. Completing the rider interface are wide 50mm footpegs that offer tenacious grip and a comfortable platform.
The 2010 KX450F is available in Kawasaki lime green, with black alumite-coated rims and aggressive graphics for a factory appearance.
Racers who ride their KX450F at designated events are eligible to receive support from Team Green™, Kawasaki’s amateur racing support program. Each year, Team Green provides regional support vehicles and highly trained technicians at more than 100 events throughout the United States, offering technical information and assistance to those who race Kawasaki products. Kawasaki also offers a comprehensive contingency program for amateur and professional riders who place well at designated events.
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