After Ryan Villopoto won back-to-back Supercross championships and last year’s outdoor motocross title, Kawasaki could be excused if it sat on its hands and left the KX450F unchanged. Unfortunately for the competition, Kawi couldn’t leave well enough alone.
On the $8699 2013 KX450F, the big news is the KYB Pneumatic Spring Fork (PSF), which saves 1.7 pounds in large part by ditching the metal coil springs. Much like a mountain-bike fork, the PSF is tuned using a hand pump (see gallery below) to set air pressure.
Mods to the dohc, four-valve engine include a new intake cam, piston and ignition settings to create a more userfriendly power curve.
Last year, the KX250F got an industry-first dual-injector EFI system. This time around, the $7599 KX gains the three-map ECU from the 450F; it allows riders to choose among three types of power delivery by exchanging jumper plugs on the ECU. Other engine updates include a bump in compression to 13.8:1 and a new resonator-chamber exhaust system.