KTM DUAL-SPORT SHOOTOUT

 

Things have changed for off-road riders. For 2017 KTM doesn’t offer separate bikes for the off-road and dual-sport categories. The EXC line is supposed to cover all bases, everything just short of full-fledged racing. The XC-W four-strokes of the past are gone. Are the new-age dual-sport bikes really good enough to take their place in the off-road world? And which of these three is best suited for the job?

 

THE HOW & WHY
It was never KTM’s master plan to stop making off-road bikes. The U.S. government forced the issue. Off-road bikes and street-legal bikes were both required to meet federal noise and emission standards. It didn’t really make sense to go through the certification and homologation process for a dirt-only bike and then not go a step further and make it street-legal. For purists, KTM offers its closed-course off-road XC line, which isn’t subject to regulation at all.
This year’s EXCs are completely new bikes, with new motors, new frames and new suspension. The motors are very similar to those in the motocross bikes that were introduced last year, but the EXCs have provisions for kickstarters, whereas the race bikes don’t. If you want a kickstarter as a backup to the electric starter, you can buy a kit. All three bikes are much, much lighter than they were last year. In fact, they’re even lighter than the XC-W dirt-only bikes of 2016. Score one for the new master plan.

KTM 500EXC
Just like the motor in the 2016 KTM 450SX-F motocross bike, the new 500EXC motor has a single-overhead-cam layout, but the whole engine is more compact and lighter than the one it replaces. To give it a displacement of 510cc, the stroke is 8.6mm longer. It has a new 42mm throttle body and a Keihin injection system, but the mapping is said to be locked in the approved setting. All of the emissions equipment is invisible. There’s no air pump hanging off the side of the motor like on a Honda XR650L, and the evaporative canister is hidden within the frame. The bike also has some fairly extreme features to deal with noise restrictions, beyond the muffler itself. KTM engineers placed a reed valve between the air filter and the throttle body to silence intake noise. Even the Continental tires were selected to minimize noise in a drive-by sound test. The gearbox is a six-speed, and the diaphragm-spring clutch is hydraulically activated.


KTM is keeping the PDS rear suspension on the EXC line, so there’s no linkage to limit ground clearance. The WP Xplor shock is new this year and is another source of weight loss. In front, KTM has its new two-spring WP Xplor 48 fork. This version has no preload adjuster but does have topside clickers for compression and rebound damping.
It all comes together in an amazing overall package. First things first: the bike weighs 244 pounds with an empty tank on the fabulous Dirt Bike scale. That even includes the mirrors. To put that in perspective, a Yamaha YZ450F motocross bike is only 8 pounds lighter. The electric-start YZ450FX is 7 pounds heavier, and the dirt-only KTM 500XC-W from last year was 5 pounds heavier. So, already the EXC has cleared the first big hurdle to being considered a legitimate dirt bike. The new EXC’s power is outstanding. It’s so quiet that it’s misleading. The noise level can be drowned out by an electric weedwacker. You can easily be sucked into grabbing too big a handful of throttle. Throttle response off the bottom is instantaneous, almost jerky. Higher in the revs, you don’t get the outrageous output that you do on the competition models, which is quite reasonable for trail riding. Any more and it would just be showing off. It’s interesting that KTM geared the bike for dirt. Usually, dual-sport bikes have super-tall overall gearing that makes them idle at freeway speed; it also helps with the drive-by sound test. The EXC is still geared low enough for super-tight canyons. On the other end, it’s not especially comfortable at 65 mph. The motor is revving high, the wheels aren’t balanced and you feel a lot of vibration through the footpegs. In other words, it feels just like a dirt bike.
Actually, the most limiting factor in the dirt is the tire selection. The Continental TKC80s are more suited to adventure bikes and don’t hook up well in sand or mud. Anyone who is serious about riding off-road can easily find DOT knobbies that perform better. Some riders might also feel the need to make mild suspension changes. We already know that the Xplor 48 fork has outstanding potential. The 500 is cushy to the point of overkill. Clearly, KTM engineers wanted to make the bike as plush as possible but probably went too far. The fork and shock are so soft that you get too much chassis movement when you try to ride hard. Whoops are intimidating, and you can’t be too aggressive on rough terrain in taller gears.
That can easily be fixed. EFI glitches might be more difficult. Once in a very great while the bike will cough and die. To be fair, this is actually typical of any big four-stroke. We’re talking about 510cc of displacement here. In this case, however, we’re helpless to try different remedies, because the whole system is supposed to be tamper-proof. That also means that no engine modifications are a good idea. If you change the exhaust or intake, the flame-out issue will likely get worse.
We can live with that. The 500EXC is much more of a dirt bike than it is a street bike. In fact, it’s a better dirt bike than the dedicated off-road four-strokes of a few years ago. And, with a little attention to the suspension and rubber, it will be an even better trail bike than the closed-course, off-road 450s available right now.

 

KTM 350EXC
KTM followed the same formula to make the 350 dual-sport bike, although this motor is completely different from the 500’s. It has a double overhead cam and is more closely related to the 250F family of powerplants. The engine is based on the motocross model that was introduced in 2016, but with several key changes. The hydraulic clutch is KTM’s DDS design with a diaphragm spring, whereas the MX model has a more conventional clutch with six coil springs. The gearbox is a moderately wide-ratio six-speed, whereas the MX bike has a five-speed and the XC has a close-ratio six-speed. KTM took the same measures to make it street-legal and EPA-certified. It has a surprisingly compact muffler with mechanical baffling, fiber packing and a spark arrestor. It also has the reed valve in the airboot. KTM calls this “Velocity-Focused Intake,” and the word is that it was developed here in the U.S. by Dave Arnold (of Honda race-team fame) and inspired by the intake in a Chevy truck. It also has the hidden evaporative canister and Continental TKC80 tires. All three bikes use lithium batteries.


Once again, the bike is very light. Without fuel and with mirrors, it weighs 241 pounds. That’s about what the first KTM 350SXF motocross bike weighed back in 2011. Even though it’s only 3 pounds lighter than the 500, it feels much, much smaller, more compact and more agile. As we always say, power has a more dramatic effect on handling than any single component of the chassis. The 350’s power delivery is completely different from the 500’s. The initial throttle response is much softer and smoother. The 350 is never jerky and always perfectly manageable. Of course, it doesn’t have the same brute force as the 500, but it still has plenty of power. And, once again, you can be deceived because of its quiet exhaust note. In the case of the 350, though, the more gradual delivery gives you much more control, and there’s still plenty of power available if you rev it a little.
The fuel injection is flawless on the 350. Past experience has taught us to expect sputtering and coughing with any bike that’s this quiet. It just doesn’t happen here. We have yet to have the bike flame out in normal riding conditions. It never backfires on deceleration, and it’s usually easy to start.
In the dirt, the stock tires are the 350’s biggest drawbacks. And, as with the 500, the suspension is very, very soft. In both cases, however, the 350 is less limited. With less power, you don’t push traction to the edge quite as easily, and you don’t hit bumps as hard. On the other hand, the 350 works pretty hard to keep up with highway traffic. It’s not the type of bike you would use for a long commute. On all three bikes, the fuel tank is small (2.2 gallons by our measurement), so you can’t go far anyway.

KTM 250EXC
Outwardly, you can’t see much difference between the 350 and the 250. Both the bore and the stroke are different, but you would have to know your KTMs pretty well to tell one from the other. On the left side, you can see that the 250’s cylinder is shorter, and on the right, the head is different. Everything else is identical. Once again, though, there’s a very big difference in the way they run and act. The 250 only weighs 1.5 pounds less than the 350, according to the scale, but, as we’ve come to expect, it feels dramatically lighter. You even imagine that the 250 is physically smaller than the 350. It’s not, but the power delivery has that much of an effect on your perceptions. The 250 has a very soft power delivery down low. That combines with very little engine braking to make the bike super easy to ride. Even though it has the same shortcomings in rubber and suspension as its stablemates, those things simply aren’t much of a bother.


The fact that it’s so difficult to modify these bikes might be more of a problem with the 250. The low-end power is pretty mild. It is a 250 four-stroke after all. If you want to pick up the pace, you can’t just roll on the throttle and go. The 250 likes to downshift or two and a lot of clutch work. Even in its MX state of tune, the KTM 250F motor has never been known for torque. On most trails, this isn’t an issue, but if you ride in deep sand or go hill-climbing, the 250 is too small. Your mind naturally wanders to exhaust modifications and other things that could turn out to be a can of worms. Still, compared to dirt-only 250 four-stokes, the 250EXC is in the hunt, and it will blow any other 250 dual-sport bike out of the water.
That brings us to the two questions we set out to address. First, are these three dual-sport bikes worthy replacements for the now-discontinued, dirt-only KTM XC-W four-strokes? That answer is clearly a big yes. They’re lighter. They run cleanly and smoothly, and after the first set of tires is worn out, the playing field is completely level. The fact that today’s dual-sport bikes are difficult to modify has been rendered irrelevant by increasingly tight regulations that face all off-road bikes. The biggest drawback to having dual-sport bikes replace off-road bikes is the price. The 250 is $9399, the 350 is $10,399 and the 500 is $10,699. Last year’s XC-Ws were around $700 less expensive, model for model.
The second question: which KTM? That really does depend on where you ride. The three bikes get more difficult to ride as you go up in size and power. The 250 is the best on tight trails as long as they’re flat and hard. The 500 has all the power that anyone would need, but you pay a price in manageability. That leaves the 350 as our favorite. Horsepower is never an issue, and it’s still a sweet, friendly bike, no matter where you ride. Predictable? Sure. But sometimes the answer is spelled out in the question.

 

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