Kawasaki has released the first pictures of its updated 2008 model four-stroke motocross motorcycles, the KX250F and KX450F
Both the Kawasaki KX250F and KX450F motorcycles have been subject to detail improvements, with the KX250F getting more substantial changes.
New crankcases have been introduced with increased rigidity around the crankshaft and transmission input/output shafts to improve reliability, and new engine mounts on the frame with 10mm longer spacers are claimed to reduce torsional rigidity for better feel and traction.
The suspension has also been tweaked with a smaller air gap in the forks for better compression damping, and the fork piston rods are 0.5mm thicker for better mid-stroke response. The rear shock has been reset to match the forks, and the ride height has been raised for better agility.
The Kawasaki KX450F motorcycle has been tweaked for more user friendly and smoother low engine speed throttle response to reduce rider fatigue. Kawasaki says it has achieved this with new wedge-shaped crank webs and a heavier flywheel, which also helps reduce vibration. Reliability is also claimed to be improved by a harder con-rod surface material, revised oil pump design and a redesigned piston-cooling oil jet to stop oil becoming trapper under the piston.
A new gear-shift cam and a wider track shift drum should improve gear changes, and new intake design has been employed to improve throttle response. The ignition has been altered for better started, and the oil pump cover is now held in place with an extra bolt for better oil sealing. The suspension has received minor tweaks to improve balance and suspension bottoming characteristics, and a new friction reducing material on shock and fork internals.