Kawasaki’s KX450F is no stranger to success on the race-track, thanks to reigning Supercross champion Ryan Villopoto. The big Kawasaki MX Thumper has also dominated MotoUSA’s 450 Motocross Shootouts, claiming top honors in the last two comparison tests (2013 and 2012). For 2015 Kawasaki updates its 450F with a new air-fork from Showa. Engineers also managed to pare down weight slightly, as Kawasaki claims a curb weight of 247.1 pounds for the 2015 KX450F – a decrease of 0.9 pounds from the 2014 model.
Internal geometry for the liquid-cooled 449cc Single remains unaltered, including the 96mm bore and 62.1mm stroke. The KX450F does make use of a revised Bridged Box piston design, which makes use of reinforced external ribs and shorter skirts. The new piston, which Kawasaki claims is “pulled straight from the factory racer team,” bumps compression ratio up from 12.5:1 to 12.8:1. Kawasaki also promises “stronger mid-range hit as well as a stronger feeling at high RPM” from its revised engine.
ECU settings for 2015 have been altered to increase traction. The system works by retarding ignition when the computer detects excessive wheelspin. Kawasaki also touts the ECU is programmable, with custom engine maps available along with the three selectable maps (Standard, Hard and Soft). These latter settings return from the existing model, and are switched via DFI (Digital Fuel Injection) coupler caps. The launch-control system, which Kawasaki is keen to promote as an industry first, also returns for 2015 – with the technology having made its way into other recent 450 MX offerings (like the 2015 Suzuki RM-Z450).
The 2015 KX450F gets a new fork, swapping the Kayaba air-fork with another pneumatic design from Showa.
The KX450F’s major chassis update for 2015 is a new front fork. Kawasaki drops last year’s Kayaba air fork for another pneumatic design, this time from Showa. The SFF-Air TAC fork (Separate Function Fork – Triple Air Chamber) is also claimed to be derived directly from Villopoto’s factory race bike. The TAC system is comprised of three separate chambers – inner (145 psi), outer (7.25 psi) and lower (130.5 psi). Claimed benefits from the new Showa unit are more adjustability, better bump absorptions and increased durability. Air pressure within the fork is adjusted by the Kawasaki Genuine Accessories 0-300psi Digital Air Pump, which is a standard feature on the 2015 model. The fork offers 22-position adjustment for compression and 20-position for rebound damping.
A fully-adjustable Showa rear shock teams with the new fork, with the valving having been revised for stronger damping. Kawasaki also offers a 1mm longer suspension tie rod option, which reduces seat height by 4mm.
The 450 sources a lighter subframe, which it shares with the KX250F. New axles also shave 31 grams up front and 32 in the rear, contributing to the modest weight reduction.
Another update for 2015 is a larger diameter front brake rotor, growing from 250mm to 270. The front disc in pinched by a twin-piston caliper. The rear disc remains a 230mm disc and single-piston caliper.
In the styling department the ’15 model carries over for the most part. The most noticeable exception is the fork, with the exterior finish swapping from gold for silver. Kawasaki’s lime green color scheme and graphics return, along with the black wheels.
Stay tuned for more information, including a first ride report next week after MotoUSA samples the revised 450 Kwakker.
2015 Kawasaki KX450F Specifications:
Engine: Liquid-cooled, four-stroke single with DOHC and four-valve cylinder head
Bore x stroke: 96.0 x 62.1mm
Fuel Injection: DFI with 43mm Keihin throttle body
Compression ratio: 12.8:1
Ignition: Digital DC-CDI
Rake & Trail: 27.9 degrees / 4.7 inch
Front suspension: Inverted Showa SFF-Air TAC fork with Triple Air Chamber, DLC coated sliders, 22-position compression and 20-position rebound damping adjustment, with 12.4 inches of travel.
Rear suspension: UNI-TRAK linkage system and Showa shock, 19-position low-speed and 4 turns high-speed compression damping, 22-position rebound damping and fully adjustable spring preload, with 12.4 inches of travel.
Front tire: 80/100-21
Rear tire: 120/80-19
Front brake: Single rigid-mount 270mm Braking petal disc with dual-piston caliper
Rear brake: Single 240mm Braking petal disc with single-piston caliper
Overall length: 86.4 inch
Overall width: 32.3 inch
Overall height: 50.2 inch
Wheelbase: 58.8 inch
Ground clearance: 13.4 inch
Seat height: 37.8 inch
Curb weight: 247.1 pounds
Fuel capacity: 1.64 gallons
Color: Lime Green