Dead. Not dead. Dead. Not dead. What is it with 250 two-strokes? According to AMA-sanctioned amateur national championship races and the Women’s class at the outdoor nationals they’re alive, well and kicking (although a lot less than the four-stroke competition). But is there a place for the two-stroke 250 in the real world of journeymen motocross hobbyists or weekend warriors? KTM thinks so and we agree. But this doesn’t mean it’s only for kids and women. Just ask Mike Alessi, who rode our 2010 for a few photos and couldn’t stop talking about it.The 2010 KTM 250 SX is probably the least changed model in KTM’s lineup for the new season. Instead of radically altering chassis geometry, shortening shocks and fine-tuning fuel delivery in line with its four-stroke brethren, the 250 SX receives just a few basic revisions for a new year with the most significant change courtesy of the all-new triple clamp, now with fixed 22mm offset replacing the 18-to-20mm adjustable clamp of yesteryear. A higher-pressure radiator cap, and new thicker gauge steel expansion chamber, plus a thicker casting for the cylinder head round out the noteworthy new stuff.The best part about these bikes (250 smokers, that is) is throttle response. The engines respond to everything faster than even FI four-strokes and the KTM delivers that response in a very controlled pull. The motor is lightning quick off idle, doesn’t tear through the traction range of its revolutions and maintains a torque-heavy pull all the way to the main jet. The transition from clutching out of a corner and accelerating down the straight is ultra smooth and allows you a moment of setup before the bike gets on the pipe in the lower-mid. There is rarely a spot where this mid-range surge comes on with a surprise. Unlike a current Yamaha YZ250, this bike does not come on ferociously or with a massive hit. Its power valve setup in stock form is butter smooth for a full-on motocross bike and can be adjusted (via different springs that come with the bike and the engine’s preload adjuster) to make a world of difference in the delivery. Once on top the power doesn’t transfer to an out-of-site rocket boost and the vibration of the 250 motor is intense. This is possibly the KTM’s largest area for improvement in the motor world. We’ve had luck with running the lightest (red) powervalve spring to pump up the top end power and overrev. KTM’s Progressive Handlebar Damping System (PHDS) or Fasst Co’s Flexx bars can really help kill the vibration buzz.
After throttle response-and directly linked to it-the second best thing about this bike is the light feel. It’s airy and fun. It’s what motocross is supposed to feel like: You know you’re connected to a ton of power but it doesn’t feel like you’re wrestling a boar. You can move it with your mind and stop it with a finger and a toe. Handling, mainly stability, is sometimes compromised in the light feeling. In the KTM’s case, this has been a constant improvement as suspension components and chassis’ improve. However, the 250 SX still feels more forward and “stink-buggy” than others. Our 170-pound riders got right along with the stock setup. Our heavy guys were feeling more kick from the rear (too soft) on braking while our light guys felt less settling on acceleration. It is the classic case of the PDS system being very spring rate sensitive for the bike to work perfect. We’re testing this bike all year so stay tuned for more updates.The new triple clamp offers a bit more stability all around and, as is the case in all KTM mx machines this year, it hasn’t affected the turning prowess one bit. Hit ruts. Destroy berms. Have fun.
Thank goodness KTM didn’t mess with a good thing. They left the power department alone and since this is one of the most user-friendly, fun and all-around fast motors to ride we’re happy they kept their hands off. However, with some of the two-stroke development we think we know is coming (think EFI, oil-injection, direct injection) we’re anxious to see what’s next. And if the four-stroke handling and suspension can make leaps and bounds forward year after year, why can’t the non-F line? Maybe it all comes along with a totally new package?The real deal here is the undeniable legitimacy of the KTM 250 SX to take anyone for a great ride. The bike is an MX weapon, easy to make off-road capable, has tons of aftermarket support and a track record for quality and durability second to none. And everyone who rode it came away smiling and impressed. Just ask Mike Alessi.Opinions:
It’s been a while since I’ve ridden a two-stroke on a motocross track, and the KTM 250 SX definitely reminded me of how flat-out fast-and fun-these bikes are. Earlier in the day I’d been doing motos on 250Fs, and when I initially hopped on the two-stroke I proceeded to over-jump nearly every double and tabletop on the track. These things have power! In the KTM’s case, the engine comes alive not with what I would describe as a hit but more with a surge; the low-to-mid-range delivery is incredibly strong but surprisingly useable. In fact, this RPM range was my favorite place to ride this bike, as venturing into the top end produces enough vibration to register on my internal Richter scale as “hazardous to dental work.” Sure, you’ll get this with any 250cc two-stroke, but why wring the bike out and rattle yourself to high heaven when you can just short-shift the bike and ride the useable wave of low-range meat? That’s my thinking, anyway. Beyond the motor, this KTM feels extremely lightweight, yet it somehow still manages to get most of the power to the ground so long as you’re in the ballpark of the right gear. It turns consistently well and handles chop decently, though I felt some kicking in the rear end that I couldn’t quite adjust out with the rebound; I think I’m too light for the shock’s spring rate. The fork springs were great for my weight but didn’t quite work in sync with the rest of the motorcycle, causing the overall handling to suffer a tad. Nevertheless, I enjoyed playing around on this machine and came back to the truck with a huge (and, I’m happy to report, toothy) grin.
-Chris Denison/ 5’10″/ 155 lb/ Intermediate
The simple fact about two-strokes is that they are making the same power as the four-strokes with half of the displacement. There is a disadvantage in the length of the power spread, with what seems about a little over half as long in the total length of RPM pulling time. Heck, two-strokes rarely rev over 10,000 RPM anyways. But there is a huge advantage in how light the bikes feel and how easy they are to throw around – thank the limited amount of centrifugal force spinning between your feet. And I can go on and on with comparisons and contrasts about which is better and which has advantages where. But in the current class structure, four-strokes have an advantage. So if you play by those rules, then the writing is on the wall. But if you live outside the constraints of some ridiculous class system and ride whatever you enjoy the most, then two-strokes make a lot of sense. Less maintenance, easier to service, less expensive, the list can go on. Though the choices are somewhat limited, KTM has continued to bring a first-class race ready bike to the table. I rode a ’08 250SX for a whole year and only swapped it out for a 125SX in 2009. For 2010 the 250SX is as good as ever and one of the bikes I’d easily consider buying if I were more of a motocross racer. No, this wouldn’t be the bike I’d be the fastest on or the one I’d win the most races on. But this two-stroke would be the bike I’d have the best balance with of being seriously competitive on (much more than on a 125) and having the maximum fun every time I rode.
Jimmy Lewis 5’10″/185 lb./Sr. ExpertSpec ChartMSRP: $6,598
Claimed weight: 208 lbs. (no fuel)
Weight (tank full, ready to ride): 229 lbs.
Seat Height: 37.0″
Footpeg height: 16.0″
Seat-to-peg distance: 21.0″