Middle ground is hard territory to defend. You always have combatants from either side trying to ram home their opinions. So when rumors began to surface a year ago about KTM’s non-conformist 350 SX-F, we, like many of you, wondered if it just might prove to be the perfect combination of power, light weight and handling. On paper, it appeared that a 350cc motocross bike would offer 250-like handling with near-450-like engine performance. Who wouldn’t be dying to ride that?
Apparently, we weren’t the only ones making such assumptions. Every time we unloaded our new Katoom testbike from the back of the truck, we got a full inquisition from curious MX riders. Without fail, the first question was: How does the power compare to a 450 or 250? So, it’s pretty obvious where the motivation for this test originated.
Our objective here wasn’t to determine the best motocrosser; we’ve already given Yamaha’s innovative YZ450F that title for 2010, and Honda’s sweet-handling CRF250R won our 250 MX comparison back in May. We instead set out to answer a few basic questions: How does the KTM compare to the establishment? Does the 350 concept have a future? Should other manufacturers follow suit? Should you buy a 250, a 350 or a 450?
Suspension performance on these ranged from good to great. Braking was much the same. Combine those attributes with “aftermarket” bars and other generally high-quality components, and there wasn’t much to distract us from concentrating on engine performance.
We conducted our testing at two different riding facilities and four tracks over the course of four days. Staff testers included pro-level Off-Road Editor Ryan Dudek and Vet Intermediate to Expert riders Mark Cernicky, Blake Conner and photographer Jeff Allen, with added input from Cernicky’s 15-year-old nephew, Nathan—an amateur Lites-class racer.
All three bikes have really good chassis—some better than others—and with a little fine-tuning or revalving, each could be optimized for any rider’s capabilities. Our goal was to compare the different engine displacements, their characteristics and how they affect handling. To back up our subjective opinions, we conducted lap times with Dudek in the seat of each bike on three of the four tracks. We also ran the bikes on the CW dyno to see what the power curves look like in graph form. What follows are our collective opinions about each bike, starting with the smallest and working our way up.
For the average motocross rider, 250cc four-strokes are very rewarding, and everyone loved the Honda. What it lacks in outright power it makes up for in a lightweight chassis that allows you to be ultra-aggressive and use far more of its performance than you can on the other bikes. “Riding over your head is not an issue because the CRF allows the rider to be in control,” said Dudek. “But you have to ride it the hardest of the group to match the bigger bikes’ pace; it simply won’t allow you to be lazy.”
That’s why “busy” describes the 250R. Keeping the engine in the power requires a lot of shifting, but perfect fueling and a screaming top-end rush keep it competitive. It even managed to turn the quickest lap time on Pala Raceway’s Vet track and came up less than a half-second short of beating the more-powerful Yamaha on the same compound’s main track. Like the other two bikes, the CRF allows the rider to alter fuel/ignition mapping to optimize the power output.
KTM 350 SX-F
This bike has Vet written all over it. For those of us who like the handling of a 250 but feel a bit overwhelmed by a 450, the KTM’s engine is a great compromise. “Power on the 350 is lacking compared to the 450, but it always seems to grab traction out of corners,” said Dudek. “I have to keep busy shifting to stay in its sweet spot, but compared to the 250, it has power everywhere!”
Not only was the SX-F able to clear every jump or obstacle it encountered, we found that we could take inside lines just like on a 450. “I could make the biggest jumps without being desperate to maintain corner speed,” said Cernicky.
“Our goal was to compare the different engine displacements, their characteristics and how they affect handling.”
It was that trait—the ability to lay down power smoothly and maintain speed—that allowed Dudek to clock his fastest lap on Pala’s sandy pro track aboard the KTM. Our biggest gripe is that the orange bike weighs only 5 pounds less than the 237-pound YZ and a whopping 15 more than the Honda, robbing it of that snappy, agile feeling we’d hoped for. But the tradeoff is electric starting, and we like that!
As CW’s current Best Motocrosser, the YZ doesn’t need much of an introduction. Explosive bottom-end and midrange power defines this bike’s engine output, while intelligent packaging allows class-leading handling—although the YZ can be intimidating for a lot of riders (Dudek excluded). We found ourselves riding conservatively so as not to get bitten by its aggressive nature.
Our use of the YZ’s GYTR fuel-injection tool, however, allowed us to create a map that delivered mellower power off the bottom, completely transforming the bike for most of us. What a difference a map makes! It was still a handful through the midrange and up top but far more manageable exiting ruts and tight corners. Compared to the other two bikes, though, the YZ can be physically and mentally taxing.
Dudek preferred the standard base map. “I love the peppy motor. It always has power and immediate snap, which gives me bursts of speed,” he said. But after struggling to match his fastest lap time on Pala’s pro track, he came to the conclusion that the YZ was so aggressive it was digging trenches instead of moving the bike forward. Maybe our old-man map wasn’t so wussy after all.
So much for being objective! We measured lap times on three different tracks, and there was a different winner on each one. The results at two of the tracks make perfect sense: The Honda dominated on the tight, twisty and hardpacked Pala Vet track, and the Yamaha kicked ass on Milestone’s soft, loamy layout, which is highlighted by three triples. But the YZ’s failure to go the quickest on Pala’s power-robbing sandbox main track, which also has multiple steep hills, was surprising. The Yamaha was a full second slower than the KTM there, proving how critical smooth delivery is, even for fast guys.
So which engine displacement delivers the goods for the largest variety of riders? On its own, Honda’s 250cc engine doesn’t match the performance of the 350cc KTM; but that level of power, combined with the CRF’s lighter weight and superior chassis, made the Honda the bike that the majority of testers enjoyed the most, although its lack of grunt made it a challenge to ride fast in some conditions. The YZ, on the other hand, calls for a serious commitment by any rider who even wants to begin utilizing its raw power. But for the expert racer who trains and rides hard on a frequent basis, the Yamaha is definitely the machine. Then there’s the KTM, which offers the best of both worlds. We all loved its power output, its delivery and its tractability, proving without a doubt that the 350cc concept makes a lot of sense. Racing class structure alone means that both 250s and 450s will be with us for a long time, but for many riders—particularly non-pro weekend warriors—a 350 offers the best balance of outright power and tractability.
We have to give the Austrian company credit for stepping outside the box and building such a bike. And we hope the idea catches on. A world with more 350s would be awesome.