With all the hoopla surrounding KTM’s revolutionary blah-blah-blah 350 SX-F, it could be easy to glance over the simple two strokes in KTMs now-even-more-broad motocross range. But, as our short day aboard the new 150 SX and 250 SX motocross machines will remind you: it’s easy to get into the mix with these fun and fast rides.
The charm of two strokes is not a mystery we need to unfold. They rule. Enough said. And while the population of smokers has been diminished in dinosaur vs. asteroid proportions over the last decade, KTM is one company pushing the reed-valve sealed envelope.
Here’s the quick breakdown on what’s new for the most fun you can have on a motocross track:
2011 150 SX New Features:
- New Frame
- New Swingarm
- New PDS shock
- New Silver EXCEL Wheels with Zinc/Nickel coated Spokes
- New Bodywork
- New Two-component Silencer with very trick injection molded mounting system.
- New airbox design
- Air flow optimized intake boot between filter and carburetor
The 150 SX is the smallest-bore motocross bike to share in the trickle-down technology the 350 SX-F development project brought to KTM’s MX lineup. Starting with this bike we see the same new-generation KTM frame styling and geometry (with revised shock “tower” mounting). This allows the PDS shock to grow longer and lay down more. The shock is still offset to the right side of the bike a bit. It isolates the shock forces away from the main frame spars too.
Performance improvements are concentrated on refining and optimizing airflow into the engine. Along with new styling benefits, the new airbox/rear fender/side panel business is hiding a specific airbox intake tract for the 150 that is supposed to get the oxygen to the lungs right on time.
The bike looks awesome. And it sounds pretty sweet, too. More than one of us journalists were fighting to ride this little sucker. And after we got our chance we came away impressed. We were fiddling with clicker settings and were pretty much maxing out the rear spring rates but for 180-195 lb dudes, the bike still handles surprisingly well. We stiffened up the fork to keep it from diving and slowed the rebound to keep it happiest. The motor sings, like it should, and after feeling the sweet pick-up in the mid range, it can make the smallest bore four-stroke sure feel sluggish in comparison. This bike is insanely fun to ride and is the only small-bore two-stroke with this level of quality components stock. Insane brakes, hydraulic clutch and a VForce reed cage are topping the list of trick must-haves for the moto elite in this class. With the 150 you get good torque for a small-bore, incredible mid-range punch and a good over-rev that is working right. This isn’t a tuning intensive built-at-home big bore kit. Those can be tough (we know, we’ve tried often and with little success). And from it’s original 144-badged brothers of the past, this bike is working immensely better.
Also, this bike has the ability to send you back in time to a place where you’re a kid again and riding dirt bikes simply rules.
2011 KTM 250 SX New Features:
- New Frame
- New Swingarm
- New PDS shock
- New Silver EXCEL Wheels with Zinc/Nickel coated Spokes
- New Bodywork
- New Two-component Silencer with very trick injection molded mounting system and bigger inner diameter.
- New airbox design
- Air flow-optimized intake boot between filter and carburetor
- New Exhaust Pipe shape and a larger diameter at connection pipe
- Newly developed cylinder has lower exhaust port, new timing and optimized exhaust control
- Noticeable increase in performance with higher torque and better rideability.
2011 KTM 250 SX Breakdown:
The KTM 250 SX is a staff favorite bike at
Dirt Rider. It delivers plenty of 250 two-stroke punch with a handful of torque to keep it under control. You can grip and rip or tug and lug—the choice is yours. It’s been a really good bike for spoiled four-stroke riders to get their manly-bike fix on and with the immense improvements in handling and suspension it’s becoming a cult favorite for die-hard two-stroke motocross racers. Free riders and FMX junkies dig it because it is light, powerful and durable and it makes a pretty damn good off-road bike with some simple mods as well. It’s basically easy to love.
For 2011, KTM has continued the development of this workhorse with new cylinder port locations, timing and exhaust valve enhancements. The power picks up with a bit more snap than previous KTM 250 SX models though KTM called it response, not snap. It is still one of the gruntiest and smooth two-strokes you’ll ever ride yet has wrist to rear wheel control that is nearing perfect. If you want to argue about how fast the bike is then you need to see a mental health professional, take our word for it, it moves. Sure you hit the wide-open part of the throttle more than on a 450cc four-stroke but you don’t hold it there forever like on a 125 or 150. The overrev on the 250 SX is clean and long and you won’t bend any valves here.
The suspension has taken a step forward. Gone is the wallowly feel in the rear, though it has gotten better and better each year of the PDS system, but it seems the new arrangement is allowing some added stiffness without the downsides of rider comfort. The bike rides a little higher in the back and therefore turns even easier than before, with no hint of added instability, a common tradeoff. Light, flickable, easy to change lines mid-turn, and easy to move around on, the bike is really good and more fun than ever.
Everyone is asking why the KTM 150 SX and the KTM 250 SX didn’t get the linkage rear shock and the answers we can give are pretty simple. First is weight. Linkage systems add weight and KTM isn’t the kind of company that adds weight without having undeniable benefits attached. Second is cost, the entry-level two-stroke range is one KTM has a handle on. We doubt they’d risk pricing themselves out of the market with a feature they don’t feel they need. Third is use. They know people aren’t using these bikes at Supercross races and in doing so they feel the PDS linkage-less system is just as good everywhere but the unique demands of the Supercross track. Everything in the world of motorcycle production is a compromise and KTM obviously doesn’t feel the addition of a linkage to the two-stroke lineup is beneficial. If they did, they’d bolt it on. They already have the frames and swingarms lying around.
Look for more full tests as we get more track time on these sweet two strokes.
Shortly after the new model intro to the media, KTM released this promotional video of their new bikes in action: