For the last five months we have been bombarded with questions about how to modify a KTM 350 SX for off-road. We have been offered no less than six converted bikes like the Stillwell Racing bike Chris Denison raced in the Denver round of EnduroCross. But we knew KTM was rushing to finish their own version of the SX converted for off-road, called, what else, the XC.
See, when you have access to drop in the correct transmission and dial in the suspension, add the things that make sense for off-road racing and leave off the stuff that doesn’t right from the get-go, you have a big advantage. Most “off-road” bikes get confused in this transition, but KTM has it dialed. Take the motocross bike, change the close transmission ratios to a semi-wide ratio, add a gear in the case of the 350, boost the gas tank volume, swap to an 18″ rear wheel, throw a light-weight kick-stand on the bike and send it off. Put a kick-starter on it too, not for backup, most will never need it for that, it is for quicker dead-engine starts! Maybe they could have played with the engine setting, but they felt all that was needed was the additional spread of the transmission.
The bikes, both 250 and 350, fire right up with spotless fuel injection and it makes us want that even more on some of the KTMs that don’t have it already. The throttle response is crisp and the bikes do not bog. There are pre-programmed maps inside the ignition box that can be activated with an accessory switch, if you feel the need. Computers on dirt bikes are great!
Riding either bike is exactly what you’d expect from the new SX-derived chassis off-road. It is light, nimble and aggressive handling. The bikes have a good steering feel in the front end that is not vague at all. It bites in with good grip and the bike is most likely a little on the twitchy side for riders used to a more trail-based off-roader. Anyone familiar with the current crop of MX bikes will feel right at home. The suspension feels very similar to the MX bike but KTM took the steps to make it work in an off-road racing world. Both bikes feel a little plusher the whole time when riding them and both ends tend to use just enough stroke to be active and not too wallowly. But they do bottom easier that an SX and maybe too easily for heavier guys on them out in the West Coast conditions we tested the bikes in. Back east you’ll love that the bikes are less reluctant to deflect, the biggest issue with MX-style suspension.
Power for the 350 is just what you’d expect a 350 to put out. But since the engine is identical to the SX, there isn’t as much torque as a lot of riders might expect in an off-road bike. This is not a trail-going powerband and you’d better be willing to rev the snot out of it to make competitive power. You can lug it but then the bike is actually pretty slow. And that is where the 250 and 350 seem to differ the most. You just can’t lug the 250F at all in comparison, as it feels like it will never pick up and go. Sure the FI works wonders in making the bike run properly and not bog in these conditions, but you have to understand they are tuned to run at full-noise and the sacrifice is low-end torque for top end power on both. And in reality if you are holding these bikes wide-open they are not that much different in speed going on open and flowing tracks. The more you are pulling out of slower turns, the more the additional boost of the 350 can be felt, but it takes a better rider to keep those ponies under control, as you actually have to use some throttle control. On the 250, you just pin it and steer.
Both machines are thin and the 2.5-gallon tank isn’t anything you’ll notice, it feels just like an SX. You don’t really feel any additional weight in the XC compared to the SX. The noise coming out of the muffler is at SX levels and we’ll be putting a Dubach Racing S/A equipped muffler on the bike to get it deeper into the off-road where a spark arrestor is required. The brakes are insane, the tires good, you don’t notice the kickstand till you park it, and we never touched the kick-starter. The gear ratios are really good for off-road for sure. First isn’t a trail-crawl speed, it is taller than that and takes some clutch work at that speed. First is a great gear to drop into in technical racing conditions, while moving forward, otherwise you’ll never use it. The rest of the speeds seem to let the motor work a little longer in each gear and the bikes never have issues pulling the next speed. Sixth seemed good for an easy 70-plus MPH on either bike.
So is this the off-road race bike you have been looking for? Yes, right out of the showroom if you are looking for a 250 or 350cc four-stroke. If you want 450 power, especially low end chug, don’t kid yourself, you have to pay for that light-weight feel somehow. And these bikes are not as versatile in the trail world as the two-stroke XCs seem to be, they are a little too high-strung in the engine to torque around like most of us ride on the trails. And if you converted your SX, well you’ll wish you had waited as KTM did about a perfect job and the price, the low side of $8000 for the 250 and the high side for the 350, you just can’t compete with about the time you take the suspension in for a re-valve.
VIDEO: We take a look at the 2011 KTM 350 XC-F here on DirtRider.com!
