Changes to the KX Motocrossers and More

Even after Ryan Villopoto won the AMA Supercross Championship the last two years, Kawasaki has not slowed down one bit on KX series development. Team Green is hungry for another one, and its 2013 model lineup proves it.

Kawasaki’s flagship motocross model, the KX450F, has seen modifications in both suspension and engine performance. The engine has been massaged for better low-end and midrange power through a revised piston crown, slightly less lift on the intake cam and revised ignition settings. Pre-programmed ignition maps are trackside-adjustable through three couplers, which are clipped to a plug on the side of the steering head for easy access. The choices are Standard, Hard and Soft (the latter designations referring to terrain). No computer is needed to change between those three maps, but owners can create their own custom maps by using the Kawasaki Racing Software Calibration Kit.

The most exciting change to the KX450F is the new 48mm KYB Pneumatic Spring Fork (PSF), which replaces the metal-coil fork springs with pressurized air. This not only reduces unsprung weight by 1.7 lbs., but also allows for quicker and easier tuning as only a simple hand pump is needed. A stronger swingarm complements the new fork, while a lightweight, petal-type rear brake rotor with a single-piston caliper brings up the rear.

New, wider handgrips using softer material allow the riders to slide his hands up to 20mm closer together for a more compact riding position. Retailing for $8699, the 2013 KX450F comes in Lime Green with black-anodized rims and graphics inspired by the Team Monster Energy factory racebikes.

The most changed model in the 2013 KX lineup is the KX250F, with a revised frame, engine and suspension. Kawasaki’s engineers slimmed down the frame 4mm across the main spars and designed smaller radiator shrouds and side covers, providing greater freedom for the rider to move around on the bike. The new frame has revised steering head gusseting, a new shock mount tower and a new rear engine bracket that helps optimize frame flex to improve rear wheel traction. As with the KX450F, wider handgrips with lower-density material bookend the Renthal bars, allowing for a more compact riding position.

Kawasaki has further refined the Digital Fuel Injection (DFI) system by relocating the second injector farther upstream of the throttle body. The two injectors have different body sizes but put out the same total capacity during each cycle. The second dose of fuel on acceleration maximizes the high-rpm power while also widening the powerband. The intake ports have been widened and the intake tract now has a straighter path, contributing to stronger top-end performance. A shorter exhaust header and muffler enhance low-end power, while an added resonator chamber keeps noise down to 94 decibels.

The Showa Separate Function Fork (SFF) has been enhanced with a 1mm-larger tube size, increasing rigidity and allowing a larger main piston and sub-piston to be used. The compression rods have now been inverted, increasing the volume of oil at the bottom of the fork for a more progressive increase in damping force while also helping to relieve the chances of bottoming out. The 2013 KX250F comes in Lime Green for $7599.

The liquid-cooled two-stroke KX100 is the bigger brother to the KX85 and KX65, and comes with more power and a wider powerband than its smaller siblings. Kawasaki’s Integrated Power-valve System varies exhaust port timing, bringing more low-end torque. Power is fed through a six-speed transmission to help keep it on the pipe.

The fuel tank is specially designed to fit inside the frame to lower the fuel load and center of gravity. A 36mm inverted-cartridge fork is fitted to the front with 18-way adjustable compression damping, while a Uni-Trak shock features adjustable compression, rebound and spring preload settings. The Lime Green color, aggressive graphics and black-anodized rims impart a familial feel to the KX100, which sells for $4249.

The KX85 is the middle child in the KX two-stroke lineup, and basically shares most of its components with the KX100. Due to the smaller engine and smaller wheels, weight is reduced by nearly 4.5 lbs., overall length is shortened nearly 3.5 inches and seat height is lowered by about an inch. The KX85 is also $200 cheaper at $4049.

Smallest of the bunch, the KX65 still packs many of its bigger brothers’ features, such as liquid-cooling, digital ignition, six-speed transmission, Uni-Track rear suspension, front and rear disc brakes, and black-anodized rims. Both the fork and shock feature four-way adjustable rebound damping. Seat height is 29.9 inches and weight is 132 lbs. MSRP is $3649 and, like the others, it’s only available in Lime Green.

PHOTOS: Kawasaki