: The KTM 350 is the manufacturer’s most sought-after engine size.
FACT: KTM sells more XCs than SXs by a considerable margin.
FACT: The 350 XC-F has a smoother, plusher yet hard-core suspension system.
FACT: With a larger fuel cell, 18-inch rear wheel and sidestand, the XC-F is far more versatile than the SX model.
FACT: You can easily race moto, a GP or play-ride with the XC-F.
FACT: It’s too plush for SX. This bummed out our vet riders.
FACT: Our staff and test riders were polled: 350 SX-F or XC-F? The XC-F took the win for one simple reason: same power, broader palette.

The 350XC-F shares an identical engine with the SX-F model but with a few caveats. The XC-Fs have six-speed gearboxes, while the SX-Fs have close-ratio five-speeds. First gear is lower, with each gear a little  than 1 percent longer than the SX tranny. Fifth gear is relatively close, and, of course, with a sixth cog, you have additional top-end speed. It uses the same CSS clutch (coil spring steel), with a durable steel basket and eight clutch plates with steel carrier discs. The Brembo hydraulic system has a new master cylinder that offers a great pull with good feel and precise modulation.
The dual-overhead-cam engine is identical to the SX-F’s and is fitted with titanium valves, optimized porting and flow characteristics that allow for a 13,000 rpm ceiling and overall power numbers that run close to the 450’s. Keihin’s 44mm throttle body and injector position designed by KTM target instant and exact power as well as good fuel management. KTM has upped the quality of the wire harness and now fits the connectors with enclosed rubber boots. We fit an optional PowerParts map-select switch (under the saddle) that offers a standard map, a soft (or slick terrain) map, and a hard (or boost) map.
Like the SX line, the XCs use rear linkage. KTM believes their PDS linkless system targets tight off-road and enduro, whereas the XC’s link system is at home with speed hits, whoops, motocross hits and jumps. With the fork, they offer three different systems: open cartridge for the EXC/XC-W, closed cartridge for the SX, and now the 4CS closed cartridge for XC machines. We first saw this patented, four-chamber system on last year’s Husabergs. The design provides constant and sensitive characteristics to the damping, and all adjustments are made on the top of the fork via star adjusters. The compression damping is on the left and rebound is on the right. Spring rates are identical to the SX-F’s, though the damping is set for a GP or outdoor motocross. KTM’s goal was smoother action. They wanted more feel, but they wanted it to remain stiff enough to handle the versatile world it was bred for. The XC line also uses CNC-machined triple clamps like the SXs (unlike the cast units on the EXC/XC-W that focus on feel rather than rigidity).
The frame, subframe, airbox, bars and plastic are the same as on the SX machines. The tank is larger (2.4 gallons versus 1.9), though it feels no wider, and they’ve fit on a new quarter-turn cap that is much friendlier than last year’s design. The XC uses Brembo brakes with wave rotors and a new master cylinder (smaller piston). This, with the new brake-pad material, equals stronger power at the lever. Once again, CNC-machined hubs, Giant rims and an 18-inch rear distinguish this bike from those in the SX lineup. Also, the XC rear wheel now uses the larger axle (common to the SX) and is snugged via a 32mm axle nut. One note here: if you have a spare wheel, it still works; you simply have to swap out the rear wheel spacers. The front wheel is the same as last year’s. Dunlop MX 51 tires are fit up, the chain is a quality O-ring (the SX has a straight race chain), and the overall gearing is 13/50, whereas the 350 SX-F has 14/50 gearing.

This machine got some fairly radical treatment since we were in the mood to test KTM’s theory of versatility. The first place we rode in the dirt after shooting studio shots was the tight confines of the high desert, where a series of nasty summer storms had stripped the dirt down to rock. The hills remained powdery, and the traction factor was vague. Here are our thoughts.
Power: The power is strong down low. It’s too loud as an off-road machine, and we immediately fit on a KTM XCW spark arrestor muffler for this portion of the test. The new muffler hurt bottom power slightly, though the racket seemed to be cut in half. The gearing for trail work pretty much matches the powerband dead-on. First gear is nice for tight, ugly tractor work. Second is too tall for tight singletrack, but nice when the trail opens up. Spacing is excellent, and sixth is tall, making it good for transport zones. We did try going to a 52 rear sprocket (50 is stock), and this did lower second gear into a more useable area, though we found ourselves trying to lug it. This coaxed the occasional flameout and really didn’t help us get through the tight stuff quicker. The 50-toother stays.
Suspension/handling: The bike was flickable, light and maneuverable, especially since we are used to riding a 500EXC on these trails. The 350 wants you to push. Aggressive tendencies were rewarded as the suspension chewed harder on the trail hack. The bike stayed planted, cornered better, and ultimately had us hooking up and hauling timber. The new 4CS WP suspension targets GP racing, and, to be honest, is a little “not plush” for rock, roots and trail junk. One note here: it’s way more compliant than the closed-cartridge SX fork, but almost feels SX stiff compared to the XC-W open-bath WP system.
As for the shock, all is good. It absorbs trail refuse quite nicely, offers good traction and keeps the wheel on the ground for enhanced braking in weak traction. The stock spring is a little weak for pilots pushing 180 pounds, but still seems to hold its head, absorb and react nicely. In speed zones where high-speed hack would make the link-less PDS system float and wallow, it stays straight and true.
Other off-road notes: We got great gas mileage, though without a speedo it was hard to gauge perfectly. On our 45-mile loop, it used a little over half a tank. That’s quite good. We fit on a Power Parts plastic skid plate that weighed nothing and did a great job shielding the frame and cases from abuse.
The GP test: This actually includes a two-track moto evaluation, and the machine flat out rocked! Whereas the new 4CS fork and linkage shock felt a little stiff and over damped for technical off-road, on an outdoor motocross track and beat-up long course, it was plush and refined, especially when compared to the production moto settings. Our testers ranged from 170 pounds to 215, and all found the suspension to be a giant plus! Handling-wise, the XC took in the big hits with little wincing and craved the jitterbug nuances that hammer a well-worn circuit. In direct comparison to the 350SX model, every one of our testers praised the lack of jolt and improvement in control. Remember, this was a true outdoor-type venue with big jumps, whoops and square-edged carnage but no timing doubles and triples.
We set the rear shock at 105mm of rider sag. The fork stayed in the 10–12 out on compression range (same for rebound), and we motoed. It’s interesting to note that not one of our MX-tainted testers noticed the 18-inch rear wheel while track bound. Off-road, the difference between the 18 and 19 is significant. The 18 actually adds plushness to the rear end, resulting in better traction in the rocks. Trackside, the 19 is definitely better in the ruts and may make the rear end more responsive.
Another strange fact surfaced concerning the five-speed SX gearbox versus the XC’s six-speed. At Cahuilla Creek’s outdoor track, it actually feels like the six-speed requires less shifting. The SX hits hard and fast; the XC was strong and long. The SX-based rider will take the five-speeder; the majority of normal pilots will crave the six-speed.

Love the kickstand! It has a little rubber loop to hold it up in case the return spring breaks. Use it for trackside adventures.
The Renthal bars and grips are superb, though a good percentage of the testers complained that the bars were too low. Enduro Engineering spacers moved them up quickly and easily.
In stock trim, the KTM saddle is fine—when it’s brand new. It wears quickly and is reduced to spongy Wonder bread in hours.
The new fork’s adjustability is wonderful and takes mere seconds. Left-side top is compression, and right-side top is rebound. Making adjustments on a track can make dramatic changes in the bike’s handling, and it requires no tools!
The brakes are intense. There is no doubt that KTM has reset the standard for proper brake strength and feel.
This machine comes with handguards. They are perch-mounted and excellent.
Great footpegs, adjustability at the handlebar perches, and air-filter maintenance and hardware. Some MX magazines snivel about the 6mm-headed plastic (looks like wood) screws at the radiator shrouds, but we’ve logged thousands of miles on these machines and have had zero issues with the fasteners.
This is one superb machine. If you look up “versatility” in the dictionary, you’d see a photo of this bike. The 350-based engine is strong enough, and it loves to be ridden hard and long. With enhanced bottom power and rev-it-to-the-moon mid to top, this wagon is designed for the guy who needs more than a 250 but will suffer with a big bore. We praise the XC baseline, larger tank, 18-inch rear wheel and sidestand. The six-speed is wickedly focused, and the suspension, especially the fork, is pretty amazing. Does it get any better? Now that’s a head-scratcher.

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