2013 Kawasaki KX450F – First Ride Building on a proven package.

Motorcycles intended for racing always get better in their second year of production. The KX450F, which received a new frame and a high-tech electronics package last year, is a prime example. For 2013, Kawasaki has refined the power delivery and improved the handling to help give the KX an edge on its competition.

Grab some earplugs before getting anywhere near the 2013 KX450F. My internal dB meter is reading too loud, and this isn’t a case of being too old. Loud pipes don’t save lives; they close riding areas. Sure, there’s a benefit to a bike that can breathe, but it wouldn’t surprise me if this thing were shooting fire out its exhaust.

It is fast, however. As in guaranteed to get you the holeshot fast. Or make that jump from the inside rut fast. With this kind of power, it’s no surprise that we are seeing supercross riders “quading” rhythm sections rather than doubling them. But please do something to quiet it down.

Besides, it’s not the unchanged wide-open exhaust that aids the KX’s quickness. Improvements to engine performance come from a new piston and intake cam that work in conjunction with a new ECU setting. Thanks to the better control of the air-fuel mixture, power delivery has been made smoother in the low to mid range, but still crisp. This helps maximize traction when laying on the throttle. The KX450F tracks out of corners nicely and pulses forward instantly while continuing make good power all the way to the top.

Back again is Launch Control, which helps riders take full advantage of traction off the gate. Also included are three power couplers that change engine performance among stock, hard terrain and soft terrain settings. As in the 2013 KX250F, the stock mapping was best, offering a good hit off the bottom but not enough to rip my arms off.

Working as described, the soft terrain map, or “aggressive power,” is just that. It offers an unruly hit that makes the KX hard to control on any surface besides soft sand. In hard terrain, or “tame power,” the bike slows and is much easier to ride because of the softened power delivery.

In 2012, Kawasaki gave the KX full adjustability for riders of varying sizes.The footpegs and bar mounts are adjustable to fit large and small alike, and this year the addition of the Kayaba PSF (Pneumatic Spring Fork) completely remedies the need for heavier riders to bump up fork spring rates, and vice versa for lightweights. Even better, the fork action has been improved, along with the bottoming resistance. I never found any harsh bottoming when using the full stroke, and the front-end felt extremely compliant on all aspects of rough (potholes, braking bumps, whoops, take-offs and landings). The fork’s stock pressure (35psi) was ideal for my 170-lb. weight. The fork is similar to that used on the 2013 Honda CRF450R. Green and Red, of note, each claim the development was specific to their respective brand.

Another benefit: The new fork is nearly two pounds lighter, which is felt immediately. That little bit of weight-savings makes the big KX feel more agile in the corners. And like the KX250F, the 450F has a new swingarm. The cast front section is 20mm longer to improve durability while also increasing torsional rigidity. Decreasing the flex is said to improve traction, and the KX really does hook up. But losing flex also means losing some comfort, so Kawasaki spent a little more time dialing in the shock. The new machine likes to have a stiffer sag setting. Last year’s ideal rider sag was around 105mm; this year it’s happy at 100mm.

The new fork and swingarm change the character of the bike slightly. The 2013 KX likes to steer more with the front than the rear. Some riders like that better, some don’t. I’m a rear-steerer and slowing down the shock rebound five clicks helped get the bike to my happy spot.

The 2013 KX450F has a powerfully smooth engine, plus predictable suspension and the adjustability to fit every type of rider. Kawasaki has made a good motorcycle even better for the masses.