The pace of development in off-road racing is relentless. A year after introducing the all-new 2012 KX450F - Kawasaki has released an updated version 2013 with more power, particularly in the lower and middle rev ranges, uprated suspension and a lot of small tweaks to make the bike more durable in the heat of competition.
The engine gets a new piston and inlet cam, with revised CPU settings and fuel- injection mapping to increase power and torque, and distribute it more usefully across the rev range, with more emphasis on low to mid-range torque.
The KX450F comes with three pre-programmed fuel-injection couplers that can be swapped in seconds to program the mapping standard, hard or soft terrain - but for those who need more fine-tuning the three supplied map-sets can be re-programmed with a laptop, using the optional calibration kit.
The bike now also has a launch control system similar to that fitted to the factory racers; push a button on the handlebars to allow full-throttle race starts in even the most treacherous of conditions. It retards ignition timing and eliminates wheelspin in the first two gears, then reverts to the pre-selected engine map when the rider hooks third.
NEW AIR-SPRING FORKS
But the biggest change to the KX450F for 2013, according to Kawasaki, is Kayaba's new pneumatic-spring forks, which replace the coil springs found in conventional front forks with pressurised air, saving weight, reducing friction and offering much easier adjustment over a far wider range of settings.
The Uni-Trak rear suspension has also been revised by moving the linkage mounts below the swing arm for more precise fine-tuning.
As with the KX250F, Kawasaki has widened the ankle area at the bottom of the lightweight aluminium perimeter frame to allow better grip and lowered the top of the fuel tank.
The body panels are smaller and the handgrips softer and longer, allowing the rider's hands to be placed further inboard than on earlier models when necessary without sacrificing handlebar width. The handlebars are adjustable, thanks to a top yoke that offers two sets of mounting slots and reversible posts that give the rider a choice of four positions to choose from: 15 or 25mm forward, standard, and 10mm back.
Adjustable brackets now allow the footpegs to be adjusted upwards or downwards by 5mm, lowering or raising the centre of gravity as well as the rider's point of view when standing.
The front brake gets a new master cylinder and 30mm longer hose, with new high-friction pads, while the rear brake now also has a petal disc.
The front mudguard and number plate are new , while the rear mudguard, as in the factory racers, is now white instead of green. The rims, also like those of the factory bikes, are now anodised black while the forks and rear shock adjusters, oil cap and two plugs in the alternator are anodised blue.
And lastly, Kawasaki has actually taken advantage of the inevitable wear and tear race bikes are subject to, by putting and embossed logo on the clutch cover that will gradually become shinier as the rider's boot wears the silver paint off.
The 2013 Kawasaki KX450F sell for R81 995.
Engine: 449cc liquid-cooled four-stroke single.
Bore x stroke: 96 x 62.1mm.
Compression ratio: 12.5:1.
Valvegear: DOHC with four overhead valves per cylinder.
Induction: Electronic fuel-injection with one 43mm Keihin throttle body.
Ignition: DC-CDI digital electronic.
Starting: Primary kick.
Clutch: Cable-operated multiplate wet clutch.
Transmission: Five-speed constant-mesh gearbox with final drive by chain.
Front Suspension: 48mm Kayaba innverted AOS-type pneumatic spring forks adjustable for preload, compression and rebound damping.
Rear Suspension: Uni-Trak linkage with gas-charged monoshock adjustable for preload, low and high-speed compression and rebound damping.
Front brake: 250mm petal disc with twin-piston floating calliper.
Rear brake: 220mm disc with single-piston floating calliper.
Front tyre: 80/100 - 21 tube type.
Rear tyre: 120/80 - 19 tube type.
Seat height: 955mm.
Kerb weight: 112.5kg.
Fuel tank: 6.2 litres.
Price: R81 995.