THE TWO-STROKE WORLD
On the off-road side, the two-stroke market still has a pulse. KTM is the big player, but small European factories like Husqvarna, Gas Gas and TM continue to sell a few bikes and win a few races. Only in motocross is the two-stroke invisible. Yamaha passively remains in the game with the YZ250, a bike that hasn’t seen a significant change since 2005, but that doesn’t really tell the whole story. Just beneath the surface, there’s a lot of two-stroke activity. Last year we saw a fuel-injected Ossa two-stroke motor come out of nowhere, and within the next year, we will see fuel-injected two-strokes from Beta and Husqvarna. You can bet that others will follow.
The reason is simple. KTM continues to sell two-strokes in fairly large numbers. European companies are inspired by this, and they are rallying to the cause. The reason that Japan hasn’t followed suit is because its embattled giants are unwilling to take a risk. The economy isn’t healthy enough for that, so they will sit back, watch and wait.
For now, KTM is in the two-stroke driver’s seat. The 250SX is on top of its small kingdom, continuing to move forward as if it were the old days. For 2013, the bike got most of the same changes and updates that KTM gave the rest of its bikes. Most striking of all is the new look. The SX got new bodywork and looks just like the four-stroke that Ryan Dungey is using to dominate the National MX scene. Under the plastic, the bike has a steel frame with linkage rear suspension–that was introduced last year, with a slight increase in weight. The SX climbed from 209 to 217 pounds without fuel. This year the bike’s most significant change is in the WP fork and shock. In the past, America got the same bike as everyone else, despite the outcry for slightly different suspension. For some reason, European riders liked settings that Americans couldn’t stomach. But that’s changed. The American version of the 250SX has a shorter shock and a stiffer fork. That’s a very important development, because, historically, suspension has held the 250SX back on these shores. Both continents get new triple clamps and a new swingarm. The rear axle is larger this year, and there are changes to the spokes and hub too.
Within the motor, a very big change is the switch to KTM’s DDS clutch, which uses a single-diaphragm spring and dampers that cushion impacts to the hub. The VForce reed valve has a new shape and is now called the VForce 4. The SX motor still uses a mechanical power valve that opens more gradually than most other ball-ramp mechanisms. KTM gives each buyer a parts kit with alternative springs that allow you to change the speed at which the valve opens and closes. Other than that, the motor doesn’t have any strikingly new technology. Fuel injection will have to wait; for now, the 36mm Keihin PWK carb is still in command.
Cody Young grabs a handful of 250SX and hangs on tight.
KTM gave the 2013 250SX a number of changes, including a new Dungey-esque look.
Inside the motor, the biggest change is the new single-spring clutch that showed up on KTM four-strokes last year.
The rear end is a little more versatile. The 250SX starts off with the same disadvantage that all two-strokes have. It’s a two-stroke. There’s something about the power delivery of a four-stroke that makes the rear suspension work better. It probably boils down to all the things that make a four-stroke harder to handle: flywheel effect, overall weight and so forth. A two-stroke can’t hold a straight line through rough terrain nearly as well as a thumper, and the 250SX is no different. It seems to stop at each hole and lose forward drive. The 2013 model still represents a big step forward for KTM, though. You can work with the rear shock and come up with a setting that performs well for any given track. Hard-packed, choppy holes take a little less compression damping. Big whoops take a little more. At the end of any given ride, you’ll have something that’s pretty good, but the suspension still won’t work quite as well as that of any of KTM’s own four-strokes.