MD test rider Russ Somers recently attended the press introduction of the all-new 2008 Kawasaki KLX450R in Arizona. Let’s get right to the bottom line . . . this is the most serious, race-ready, off-road machine based on a Japanese motocrosser to date. As detailed below, this is a very impressive bike that is both whisper quiet and dialed-in for everything from recreational riding to enduro competition.
The KLX450R is based closely on Kawasaki’s KX450F motocross weapon. It has the same aluminum perimeter frame, essentially the same engine, similar suspension, and a wider ratio transmission specifically for off-road use.
Like other bikes in the class, the new KLX450R has an electric start system. The engine came to life quickly every time Russ touched the handlebar-mounted start button. That engine is derived from the brutally powerful KX450F mill. For off-road use the engine has been modified to emphasize low and mid-range power and torque with revised cam lift and timing, and flywheel mass that has been doubled in comparison to the motocrosser.
Further changes to the engine are found in the head, where intake and exhaust valve diameter have been decreased one millimeter, and exhaust valves have been switched to steel (from titanium in the motocross bike). This helps improve throttle response down low, and makes the bike more tractable (coupled with the heavier flywheel mass). The steel exhaust valves are more durable than titanium valves. The clutch cable has been re-routed to reduce effort and improve feel. Unlike some competitors, the KLX450R has the same high-performance Keihin carburetor found on the motocross model. Only the jetting has changed.
The wide-ratio transmission has a lower first that graduates to a higher fifth gear when compared to the motocrosser. The bike also features a different header and muffler that is U.S. Forrest Service approved, and meets all applicable sound level requirements.
Other changes from the motocross model include a larger fuel tank (holding 2.1 gallons); wider, slightly softer seat; headlight; LED taillight; spark arrestor; O-ring chain; side stand; and 18 inch rear wheel. A lightweight digital instrumentation package includes a speedometer, odometer, clock and twin trip meters. Although sporting the same high-quality suspension components as the motocross bike, the KLX450R has spring rates and damping characteristics revised for off-road use.
Enough with the technical stuff, let’s get to Russ’ riding impression.
The ergos are very similar to the motocrosser — slim and nimble feeling. The bike never seems to have trouble starting — hot or cold, it immediately bursts to life with a touch of the button (a manual kick starter is also attached). Like any four-stroke off-roader, it takes a bit for a cold engine to warm up, but then the fun begins.
With double the flywheel weight, and revised CAM timing, this motor is super smooth, and torque-rich. It resists stalling well, and pulls cleanly to a very healthy mid-range rush of power. It is also incredibly quiet.
How quiet? Kawasaki claims 84 db. We are not recommending this, of course, but if you were putting around on the 2008 KLX450R in your backyard, your neighbor might think you bought a new lawnmower. Really.
Could you open up the intake and exhaust on the KLX450R and get more power? Sure you could, but for most riders there would be no point. This bike makes plenty of power stock (it doesn’t require any wierd mods, such as messing with a throttle stop), without any obnoxious noise. Pro level racers, of course, will change out the pipe, open up the airbox and rejet the carburetor — and that’s it!
So Kawasaki starts with stock engine performance and sound level that arguably puts it at the head of the class. What about the suspension and handling? There is good news there, as well.
When you turn a motocross bike into an enduro/off-road machine, you want slightly softer, more plush suspension action, but without nasty bottoming. This is precisely what Kawasaki achieved with the KLX450R. It is a very good compromise between trail-rider soft and racer stiff. It soaks up square edges, but resists bottoming very well.
Russ is a big guy (over 200 lbs.), but he found the stock suspension very workable for his expert skill level and size. In the handling department, Russ found great benefits dropping the forks 5 to 6 mm in the triple clamps (the bike comes stock with roughly 10mm showing on top of the triple clamps). With this accomplished, the bike carved corners like a knife and remained very stable in high-speed chop and whoops.
The bottom line is that the 2008 Kawasaki KLX450R is a fantastic machine bone stock. In an age where loud dirt bikes are closing access to trails everywhere, the KLX450R responds to a pressing need for a quiet, high performance off-road motorcycle.
Can we criticize anything? Not a whole lot. First gear is probably too low, and virtually useless during most rides. On the other hand, the gap to second gear is a bit large, and second can seem too high at times. Russ said he would dial this out with a sprocket change. In addition, although reasonably legible, the instrumentation is pretty basic given some of the aftermarket computer systems available these days as a bolt on to your dirt bike. Last, and certainly least, the cheesy looking kick stand works well enough, but interfered with Russ’ size 12 boot when he was riding on the balls of his feet.
Despite all this, we have to advise you to ignore the nits we are picking. This is an amazing motorcycle. Although we do not have any comment on long-term durability (we may have a chance to evaluate that later), the 2008 Kawasaki KLX450R has to be on your list when you evaluate machines in this class. For additional details and specifications, take a look at Kawasaki’s web site here. The U.S. MSRP of the 2008 Kawasaki KLX450R is $7,299.
