Building off of the technology used in the new KX250F, the 450F takes tuneability to a new level. Not only can you completely customize the power characteristic of the bike, you can now adjust the bike itself to fit you.
Tuning the power of the KX450 is even easier than it is on the 250, thanks to the three power couplers that simply snap in and out and are the size of a marker lid and come with the 450. Each coupler has a unique power curve—soft, standard and hard. Each of these couplers are tuneable with the KX FI Calibration Kit, allowing you to get exactly what you want out of the engine. During our test, we tried out the couplers and discovered that the standard coupler was the way to go for most people; only the really fast riders will get their money’s worth out of the hard setting.
With the data logging option in the KX FI Calibration kit, you can monitor your throttle openings and judge which option is best for you, and tweak it from there to get the best performance. However, if you do manage to screw up the settings, there is a reset built into the software to save you from yourself. We didn’t play around with the map on the 450 and found that the standard setting was spot on for us.
Perhaps the most groundbreaking feature on the KX450F is the addition of launch control. This little magic button is something that is completely new to the MX world, and it could help out average riders off the start more than anything else. Kawasaki has achieved this by retarding the ignition in first and second gears, and as soon as you click it into third the ignition returns to its original setting.
In order to find the optimal settings, Kawasaki used information gathered from its factory race teams. They feel that this is most beneficial during the first few seconds of acceleration and allows the rider to focus on the start instead of clutch and throttle control. I guess one could almost call this the motocross version of traction control.
The improvements don’t end with the launch control; Kawasaki has taken an active role in improving its flagship model from the already successful 2011 model. The KX450 is not just about arm-ripping power, it is also about reliability thanks to the revised bridged-box piston and rings.
Accompanying the revised piston and rings is an updated intake camshaft that is claimed to increase low- to mid-range performance, with lift increased by .4mm. Also, an air bypass circuit reroutes air at idle speeds to improve throttle response from the initial throttle opening.
The 450 also received an update to the transmission for 2012; Kawasaki has widened first gear by 2.8mm for improved durability. Each gear now has four engagement dogs, up from three last year, and the shift forks have been shortened by .9mm. What does all this mean? It means that you now have a crisper-shifting bike with a reduced chance of missing shifts; we never missed a shift during our time on the bike.
Jumping from a 250F to a 450F can sometimes make the bigger bike feel like it handles like a shopping cart, but Kawasaki has gone to great lengths to prevent this. The 2012 bodywork has been stripped down and now allows for better airflow and reduced weight. Also new is reduced fuel tank capacity, down from seven litres to 6.2 litres, which makes the new tank 100g lighter. This smaller tank also keeps fuel 20mm lower, thereby lowering the centre of gravity. A real effort was made to centralize mass, including shortening the silencer by 60mm.
But does all this effort equal results? The answer is: yes. Jumping straight off the 250F and on to the 450 took no effort at all and, in fact, the 450 seemed easier to turn. The lightness of the handling was surprising and changing direction on the big 450 was a breeze.
Like the 250, the 450 received a new tie-rod arm on the rear suspension with that same goal in mind, to make the suspension smoother and increase rear wheel traction. Up front, the KX has a new lower tripleclamp that is claimed to increase the rigidity and compliment the new suspension settings. Just as the 250 has the Ti coating on the fork tubes, though the 450 uses a Diamond-Like Coating (DLC) to reduce stiction.
When we first went out on the 450, the fork felt a bit harsh compared to the rear shock, but we took a couple clicks out of the fork and it made all the difference in the world. After that, the suspension was plush but it still resisted bottoming well, even on hard hits. Even some of the hard-edged bumps on the track were no match for the KX.
The new frame on the 450F is 4mm narrower in an attempt to give it a slimmer feel. The bike was comfortable to sit on, but if you are a taller rider you will want to take advantage of the forward bar mount position. In the rearward position, the bars almost felt as if they were in your lap. Fortunately, this is where the adjustability of the Kawasaki comes into play. The rider has four bar-mount positions to choose from and two footpeg mounts to adjust the riding position.
Braking on the 450 was very good and felt exactly the same as the 250, which made jumping back and forth between bikes easy. The petal-type rotors and Nissin calipers offered a solid, confidence-inspiring feel and never threatened to get you into trouble.
Kawasaki hit the mark with another race-ready bike; it is no wonder that when Ryan Villopoto debuted the 2012 KX450F, he won both of the motos. For most people, very little needs to be changed on this bike to make it a competitive racer. Like its little brother, the wear on the engine cases may be the only thing that irks a new owner.
The big Kawi has a few extra goodies on it, including four bar settings on the tripleclamp, adjustable peg height and launch control. Cooler yet is the fact that the bike comes with three ignition maps, in the form of a little plastic piece the size of a marker cap that you can snap in and out in about two seconds (this should be described in the test above. If you don’t like any of the three settings, they are programmable, so you can map your own.
Unlike the 250F these forks worked great; they were very plush on the square-edge stuff and could easily take the big hits and whoops. I would have liked the shock to be a bit softer for my 175lbs but I didn’t want to put JP through having to change a spring, although he was ready to do it. It was close to ideal, though, and my testing partner was a bit heavier than me.
Like the 250F, this thing turns great. For those who race two bikes, I found it very easy to switch back and forth as they had very similar handling traits. At the end of the test, I did a few starts to test the launch control. Hold the button down till it starts flashing, pull clutch in, put it in second gear, hold the throttle wide open and start like you normally would. It’s a strange feeling as the bike doesn’t rev as freely, but it metes out power perfectly to the back wheel once you get going. As soon as you shift to third gear, it switches back to its regular mapping. When I was done, I noticed that my lines were much straighter when I used the launch control.
I came away very impressed with these Kawasakis. They are great at turning, they’re very fast, their handling is predictable, and they are so adjustable you can make them suit any rider.
Engine 4-stroke, Single 449cc
Bore and Stroke 96.0 x 62.1 mm
Compression Ratio 12.5:1
Valve System DOHC, 4 valves
Fuel System Digital fuel injection with 43 mm Keihin throttle body
Ignition Digital DC-CDI
Transmission 5-speed, constant mesh, return shift
Final Drive Chain
Clutch Wet multi-disc, manual
Type Perimeter, Aluminum
Wheel Travel: Front 314 mm (12.4 in.)
Tire: Front 80/100-21
Wheel Travel: Rear 315 mm (12.4 in.)
Tire: Rear 120/80-19
Steering Angle 42°
Suspension, Front 48 mm inverted Kayaba AOS with DLC coated sliders, 22-position compression and 20-position rebound damping adjustment
Suspension, Rear New Uni-Trak linkage system and Kayaba shock with 22-position low-speed and 2-turns or more high-speed compression damping, 22-position rebound damping and fully adjustable spring preload
Front: Type Single rigid mount 250 mm petal disc
Front: Calliper Dual-piston calliper
Rear: Type Single 240 mm petal disc
Rear: Calliper Single-piston calliper
Overall Length 2,180 mm (86.0 in.)
Overall Width 820 mm (32.3 in.)
Overall Height 1,275 mm (50.4 in.)
Wheelbase 1,480 mm (58.3 in.)
Ground Clearance 330 mm (13.2 in.)
Seat Height 955 mm (37.8 in.)
Curb Mass (claimed) 113 kg (250 lbs.)
Fuel Capacity 6.2 litres (1.59 gal.)