On paper, the KTM 450SX is one of today’s most successful bikes. It finished second in the Nationals, it basically wreaks a dyno and it has one of the most hi-tech motors on the market. But when we finally rode last year’s version, we were torn. It surpassed expectations in a few ways, but overall it obviously was in an early developmental stage. It needed work.  Now KTM has had a year with the 450SX in the field and it has every right to be brilliant.

 Last year’s bike was the fastest 450 motocrosser we had ever put on a dyno, but no one would have known. The horsepower peak was at high rpm and few riders bothered to hold it open that long. Instead, they felt the average low-end power, put up with spotty jetting issues, shifted early and declared the bike a yawner.
 So this year KTM refocused all the power-producing parts of the motor. It got a new exhaust cam, a full-circle crank, different ignition mapping and some valve train changes. It kept all the cool technology from the previous model; it still has an electric starter that’s compact and virtually hidden. The spark is still pulled from the battery rather than from the generator, which allows the spark plug to fire at much lower rpm, so the starter doesn’t have to spin the motor especially fast. The double overhead cam motor is like a grown-up version of the 250F motor with the same unusual system of using cam followers to operate the valves. But it’s a four-speed and is amazingly light. In fact, even with the electric starter the motor is lighter than that of a CRF450R.
 The chassis was all new last year too. It placed the no-link WP shock at a new angle and it was paired with a new closed-bath WP front fork, a Dutch version of the Showa twin chamber design. This year the fork has smaller damper rods and new valving, and the shock has had mild reworking as well.

 The 2008 model is a very different animal. After you push the starter button (still can’t get used to that), you couldn’t possibly think it’s average and you wouldn’t dream of yawning. From the first crack of the throttle, the new SX does nothing but hit you with power. The torque is amazing. Here’s the standard procedure: unsuspecting SX pilot idles onto the track, twist the  throttle hard and the bike stands straight up and down. From that point forward, he treats the throttle with great respect.
 KTM didn’t get all that torque and throttle response out of thin air. Last year’s high-rpm peak is tamed somewhat and it doesn’t rev quite as high. That’s absolutely okay with everyone involved. When you have bottom and mid like this, you really don’t need or want a crazy top end hit. One thing that makes the bottom so useable is jetting that is much, much better than last year’s, and better even than the old, well-developed RFS motor that was replaced. The SX has no hiccups that could develop into a cough and die sequence. There’s perhaps a little popping on decel,  but we can forgive that. The KTM’s motor scores big.
 The suspension scores surprisingly well, too. The rear end is kind of cushy. It deals with chop better than ever before. Same goes for the front. The hack that used to drive the WP fork crazy is reduced to an acceptable level. If you’re well conditioned by reading other tests of KTM motocrossers you know there a good chance that a “but” is coming. Sorry to be predictable. The but  this year is again in the suspension department, although it’s only a size one or two but. The front and the back aren’t terribly fond of one another. Most riders found that front end rides a little high, which kinks the KTM’s usually good cornering ability. We dealt with it by running a little more preload than usual. The good news is that it’s easily solved in the hands of a suspension tuner who knows what he’s doing. We had the same issue with the big XC version of the same bike, which we tested in the 24 Hours of Glen Helen. See “Jekyll and Hyde” in this issue.  

 You know that you’ve got a motocrosser like no other when you have to be reminded to charge it up. The battery can go flat in a few weeks of nonuse. Remember, there’ s no kickstarter. We suppose that’s the price of having a wonder button without the weight that’s supposed to be attached. We won’t complain. We also won’t complain about the four-speed. This bike can pull it off. Back to that torque. We don’t know where a fifth gear would go. Certainly not on the bottom and we don’t really want to go any faster on top.
 We will, however, complain about the clutch. Normally we love hydraulic stuff, but ours was sick this time. Even after repeated bleeding it was intermittently draggy and prevented the bike from starting in gear. Plus, the pull was hard. We think this all might be a silly misunderstanding and will get to the bottom of it with time. Stay tuned.
 We’re still dazzled by the SX. We’re still wowed by the technology. We still think it’s one of the most advanced motocrossers available for sale. Is it better than the 2008 Honda CRF450R? Is it more advanced than the new fuel injected Suzuki RMZ450? All good questions. And all will be answered as soon as we line them up and shoot them out.

* Great motor
* Good jetting
* Super light
* Electric starter
* Good bars, chain
* Turns well

* Draggy clutch
* Suspension needs balance
* No kickstarter

* Running weight, no fuel: 232 lb.
* Suggested retail price: $7298
* Distributor/manufacturer:
KTM North America

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