2007 KTM 250 SX Dirt Bike – First Test – Dirt Rider Magazine

KTM identifies and targets niche markets. The company defies rules or class structure and in the process sets trends while speculating forward. But KTM has also found success in redeveloping classes of bikes that may be falling from grace. It updated its large-displacement two-strokes when other companies stagnated, and now two-strokes in general are corporately ignored. So which maker is bringing out an all-new 250cc two-stroke motocrosser for 2007?You know it: KTM.It shouldn’t surprise you that this bike is good. These days all bikes are good; it’s how good that matters. And measuring the “goodness” comes in two steps. First is riding the bike, getting used to it, dialing it in and pushing its limits to feel when it excels and where any weaknesses lie. Then you must compare the bike with others in the class. In this case, the ’07 YZ250, Yamaha’s update of Dirt Rider’s ’06 250cc two-stroke champ (see the Dec. ’05 comparison).The bulk of the KTM’s changes center around the chassis, suspension and plastics, all of which are derived from the ’07 SX four-stroke line. The frame is essentially the same top and rear sections of chrome-moly, with the lower cradle modified and tuned to accept the smaller, lighter 250cc two-stroke engine. Look at all that room above the cylinder. It appears you could do a top end without taking off the gas tank! The suspension components are the same as the SX-F’s but with different settings. The plastic differs only in the airbox’s attachment to the carb. This bike looks light, and the scale confirmed it is 210 pounds with no fuel in the tank. The engine didn’t go unnoticed. It earned a more compact, 1.1-pound-lighter cylinder and head, in addition to a new power-valve governor assembly with improved timing control and second gear with a lower ratio.Instantly, you will feel how light the bike is. Loading, unloading and just in moving it around, we found it noticeably lighter than any 250cc-or-over four-stroke; it brings up memories of 125cc bikes. That weight, or lack of it, draws attention in more ways than just feeling feathery while riding. The SX has a bit of vibration that’s most noticeable during the first seconds on the bike. A little two-stroke tingle quivers through the bar and pegs. Getting some silicone on the pipe/cylinder joint and keeping the mounts tight work wonders. On the track, the SX, like most two-strokes, is a little dancey everywhere-the calling card of light weight and little internal rotating mass. Unlike a four-stroke, it skims across chop and bumps and feels like it skates through the bumps without ever planting the tire into one. Anytime either wheel bangs the ground, the initial hit transmits more sensation to the rider than a four-stroke would. The feel is like running more air pressure in your tires.This light feel encourages more aggressive jumping and antics in corners. You quickly realize this KTM has an uncommon knack for turning that isn’t familiar to the Austrian brand. There is a high degree of steering precision and a lot of stick. Overall, it’s one of the best bikes we’ve ridden on choppy bumps when traction was plentiful. Blessing this feeling is the layout of the super-adjustable cockpit. It makes the SX easy to move around on and offers plenty of knee grip without ever being wide. The rear of the seat is low and allows you to get back over whoops-or when panic-revving off a mistimed jump. You can get as far forward as needed and there isn’t much in the way of obstruction.Suspensionwise, the KTM is similar to the 450 SX we tested last month. The re-angled PDS shock has a wider degree of setup flexibility with a more progressive leverage ratio. Sag needs to be between 107-112mm. If there is a downside to the no-linkage rear end, it was that fast or heavy pilots were using too much stroke on aggressive jump takeoffs. Most likely they are candidates for a stiffer-rate spring. Even with the shock set at 25 clicks out on rebound, the rear looked slow to return, so we went out two clicks and found the bike was happier.WP forks take a little time to break in, and the new sealed-cartridge model used on the SX seemed harsh to a lot of riders. We started by reducing the compression, but ended back at stock after a few rides. We also found that tuning the rebound was helpful for finding the right cornering feel. Faster riders benefited from 10cc additional oil to ease the bottoming feel. KTM recommends changing the fork fluid early since the spring contaminates the oil in the first few rides. Fresh oil can help give better feel and movement. Learn to use the clickers on this bike and it can really pay off, especially at different tracks.The engine has definitely undergone a power shift via lowering and smoothing the surge and meat of the delivery. It still has a slightly lazy characteristic and a normal two-stroke idle with an early pull. From idle on up, the motor is very smooth. It has a strong midrange and then it screams, especially after the bike has some time on it. We woke up the bottom when we dropped the pilot jet from a 45 to a 42. Good torque is available from this engine at all times. It feels like it is winding up a big rubber band, and it is easy to unleash the spring effect with just the throttle. Clutch effort is nicely light and not really snappy. Its engagement is long and very controlled and never like a light switch. On the track you get used to added lever travel, and on a start you can literally just drop the lever and launch. It is that smooth. The 250 SX’s brakes are just the opposite. They are strong to the point of being touchy and take plenty of getting used to, especially the front.Where does this goodness put the new KTM? Well, it is the best two-stroke MX bike KTM has ever built, and it makes the old bike feel sluggish, heavy and a little vague handling. It is a huge step up, something we’ve found to be common in every ’07 SX we’ve ridden this year. But the company won’t be satisfied with anything but being the best. At the same time, it tries to improve and raise the performance level of motocross bikes up a notch. So to truly find out if the 250 SX is a success, we lined up the ’07 KTM against the new ’07 Yamaha YZ250 for a shootout. You’ll have to keep turning pages to get the full skinny.

Middleweight Showdown
Yamaha YZ250 vs. KTM 250 SX

With droves of riders switching from 250 two-strokes to 450 four-strokes and the bulk of development going to the thumpers, it is almost surprising that the 250 two-stroke is alive and well. But it is, especially if you are KTM with an all-new bike in a mostly minor-revision year for the big four Japanese brands. We saw no point in rehashing old news and got straight to the point. We prepped the Yamaha YZ250, a lightly revised version of our 2006 class champ, and left the rest behind. We chose to concentrate on the battle between the best and the newest 250cc two-strokes at hand. A large portion of 250cc two-strokes are now finding homes (at least part-time) off-road. The Yamaha can be modified to do any type of competition with only a little aftermarket attention, but KTM has two specific 250 XC models designed for that, so we won’t address the off-track performance in this comparison.Motor
With 450s being so powerful and 250Fs just getting by, many riders feel stuck in the middle. If that is your problem, here it is a solution: These premix-burning, easy-starting, light and simple two-strokes have wings. Lately, the Yamaha has been regarded as having the perfect two-stroke powerplant. It has insane wrist-to-rear-wheel connectivity and snap and responsiveness that four-strokes dream of. There isn’t a lot of torque feel, but bogging this bike is as uncommon as a bad riding day in California. It is crisp from the first crack of the throttle, and it pulls smoothly, strongly and deliberately all the way to a respectable top-end. And if there was a downside, it is that the motor can be too responsive or aggressive for less precise wrists. That is where the KTM fits right in. It has more of a ding-ding-ding at idle and takes a few rpm to clear itself out. It, too, is very smooth but always packing a bit more internal grunt, or torque, if you will. It has a healthy mid and hauls the oats on top, revving just a bit further than the Yamaha. Which is faster? Neither, they are dead even. In starts, drag races and racing around the track, as long as the riders are of equal ability, the motors pull the same, and it took other factors to yield an advantage, mainly traction, clutching and shifting.On the start line the KTM is simply simple. Its hydraulic clutch may not give a crisp or sudden grab when released, but it can be dropped leaving the line and seemingly do the work for you. It takes more of a pull on the gear lever to make a clean shift, especially from first to second, but that’s something you get used to quick. The Yamaha’s clutch and shifting are topflight, and its clutch bite is snappy. And adjustment is critical, on both bikes, for smooth full-power shifts. Both machines have well-spaced gearboxes, but the KTM seems to like third and fourth gear whereas the YZ utilized more second and third.Suspension
Yamaha has never been a 250cc class overall suspension favorite with our test riders, but very few of them moved far from the YZ’s basic setting, either. They just ride it without complaining or feeling the need to adjust it. Both ends are plush, progressive, resist bottoming and rarely do anything funny.The KTM, on the other hand, is in a whole new league with the linkageless rear shock. The KTM is definitely picky about setup, especially in the front end. Riders all found they could dial in the ride they wanted with a little tuning, yet either the fork is just a little harsh or the light feel of the bike gives that feeling. The WP inverted fork has a nitrogen-charged bladder, like a shock, that will allow additional tuning, but for all but the best of suspension tuners, it is a bit of a mystery. In the rear, the KTM was better on the chop and seemed to get better traction over small to midsized bumps. It bottomed both ends just a bit easier than the YZ.Which is better? Honestly, they both get the job done, but one needs less attention, and for most guys that means the YZ has the KTM covered.Handling
Here is where these two bikes begin to take 10 steps and get ready to draw. The biggest difference in the ride is the lightweight feel of the KTM. It is nearly 10 pounds lighter on the scale, and you feel every one of those when riding. It is so light (illegal for AMA Pro Racing!) that KTM test riders reportedly added a 10-pound lead-weighted skid plate to get used to the bike after four-stroke testing. The SX flicks around easier, changes directions quicker and will dice underneath the Yamaha in ruts or on flat turns. The SX weights the front end and sticks the tire but doesn’t get crazy with it and want to climb out or understeer in ruts, either. Once the speeds go up, the KTM dances around a bit more, causing some riders to suggest instability flaws. For sure, it doesn’t feel as flat-out confident as the YZ. The Yamaha is more planted, and even though it turns fine, it requires more work in either ruts or hard and flat turns. It takes a little more effort to throw around in the air as well.What it really comes down to is how much you like the lightweight feel. The KTM, as the lighter of the two, can feel twitchy and less confident or it can make you feel like a hero; its all in a rider’s preference. One of the side effects of being light is an increased amount of vibration, which both of these bikes have-the KTM buzzes just a bit more.Both of the bikes are easy to move around on, and size does matter. The KTM has a roomier rider compartment stock, and that space can grow (or shrink) with an easily adjustable top triple clamp, all stuff that helps the rider dial in his bike’s handling.Bits and Pieces
In the past, both of these bikes have been as solid as rocks in the durability department, so we have no concerns there. They are both outfitted with top-of-the-line equipment from the front fenders back. Neither has anything we’d even call a serious flaw. Still some things stand out. The KTM has brakes that are stronger than most works bikes. Some riders like them; others hate them. The front is more blatant than the rear. There’s hardly a sidepanel on the KTM, and the style, at the moment, is shocking and generated a love/hate reaction as well. And then there is the plain fact that a lot of riders just don’t see KTM as being able to build or play at the same level as a company like Yamaha. KTM has a giant strike against it just from rider preconceptions. To this day, we see these biases in the opinions of even our test riders. Just before being demoted to photo model, one rider commented, “How can you even consider comparing it with the Yamaha?” We sometimes wish we could just paint the bikes all black and have everyone ride, brands unknown. This truly affects opinions about the orange bikes at the MX track to the same degree they prejudice off-road comparisons. But if you remain closed-minded like that, you will never really know, now will you?The Winner
The safe choice is simple. More riders will like the Yamaha mostly because it is a Yamaha and not a KTM. The YZ250 is an excellent motorcycle.But riders should be more specific than that. Smaller riders fit the YZ better. Riders who like a lot of snap from an aggressive motor will dig the YZ. If you aren’t too picky or into tuning your suspension or are maybe just plain lazy about it, you can get away with a lot more on the blue bike. We didn’t have a test rider who didn’t like the YZ. The KTM comes very close. It fits larger, especially taller, riders better stock. The motor is smoother and easier to ride and, combined with the clutch feel, an easier match with lesser skilled riders as well. The KTM rewards those savvy with suspension setup. And in turning and traction out of turns it will challenge anything out there. There is nothing at this weight level with this much power. Who wins? You do, especially those torn between 250cc or 450cc four-strokes. Premixing is still alive.Specifications

2007 KTM 250 SX
Actual weight (ready to ride, no gas): 210 lb
Seat height: 37.5 in.
Footpeg-to-seat distance: 20.5 in.

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