MOTORCYCLE – Kawasaki Updates Motocross Line
July 28, 2005
Filed under Features
Kawasaki Motor Corp, USA, Irvine, Calif., recently revealed three '06 motocross models, but dealers eager to see them will have to wait until Kawi's annual meeting in September, and fans of Team Green will have to wait just a little longer.
While the 2006 KX250 receives a number of updates - Kawasaki said it fine-tuned the engine, suspension and brakes - the real news comes from a revamped KX250F and KX450F.
Kawi says KX250F produces significantly more power than the 2005 model it replaces, and like the new flagship KX450F, the KX250F sports an all-aluminum perimeter frame. To further complement the chassis, a Showa twin-chamber fork keeps the oil and air in separate chambers for consistent damping performance during long motos while, on the rear, a new UNI-TRAK rear suspension system features an alloy swingarm with tapered spars and revised linkage ratios to maximize traction under acceleration.
Motor enhancements include revised intake and exhaust ports, a revised combustion chamber for stronger low- to mid-rpm performance, new cam profiles, and a higher 13.5:1 compression ratio. To compensate for the increased output, the piston now has a thicker crown. Other engine modifications include stiffer valve springs to help ensure reliable valve control at high rpm; a surface-hardened crankshaft for additional rigidity; more efficient oil pumps that increase oil flow by nearly 20%; a new stick ignition coil that reduces overall weight; and newly designed, high-capacity Denso radiators that deliver better cooling due to more tightly packed cores and a new fin design.
The clutch and five-speed transmission have also been modified to match the more-powerful engine, a Renthal aluminum handlebar and an aluminum skid plate are affixed, and there's a new seat and bodywork.
The 2006 KX450F features a new, liquid-cooled, 449cc four-stroke engine; transmission; swingarm; UNI-TRAK rear suspension; and all-aluminum perimeter frame.
Kawasaki says the engine's hand finished intake ports maximize intake efficiency, while lightweight titanium valves and aluminum valve retainers reduce reciprocating weight for reliable valve control at high rpm. The revised engine is matched with a new four-speed transmission combined with a manual, multi-disc wet clutch.
The bike also utilizes the newly designed, high-capacity Denso radiators to provide increased cooling; and the new long-fiber packing to keep noise down and maintenance quick and easy.
Kawasaki says the frame's twin-spar design gives the KX450F optimum balance of torsional and longitudinal rigidity. The frame was designed so that the center of gravity and key chassis dimensions would work together to enhance the rear tire's ability to drive the KX450F forward instead of squatting under acceleration. Additionally, the four-stroke engine sits in an upright position within the new frame to further aid overall traction.
Kawasaki has not revealed pricing for the three '06 models.
- Guido Ebert