The 400 feels slim and light for a fully off-road-equipped E-start four-stroke. The shorter stroke means that the biggest part of the engine's rotating mass has less of a gyroscopic effect on the chassis, and the bike flicks back and forth through right/left turns with less input than the 450 or 525 require. There are also power differences. The 400 has a more electric delivery than the 450, so the front end requires a bit more work to get in the air at an instant's notice. However, it still has plenty of power for most off-road scenarios-just dial up the rpm until you have enough. We found that the 400 would climb astonishingly difficult sand hills in the desert yet was perfectly docile in the tight brush and decomposed granite boulders and stair-steps of Mexico. Slippery conditions and root-crossed, snotty clay trails in the East are where it will really shine. First gear is generally low enough, but riders at high altitudes or with limited open terrain frequently drop a tooth on the countershaft. Then there is that amazing sixth gear for transport sections. If you have the 400 flat out, you are probably going way too fast for good sense, but it sure is great for making the miles go by quickly without excessive rpm.
They should just divvy up these bikes: Dealers from Central Texas east should get 400s, and the 450s should come West. Sorry if I spoiled it for all you Eastern guys who have been spankin' two-stroke heinie, but the truth is out now. -Karel Kramer
The 3OO WinsI'll admit it: I'm a two-stroke-supremacy bigot. It's a result of my upbringing, but I can't blame anyone but myself. Every time I ride, I think I'm racing. I actually pay money and enter an event much less often than I used to, but that still means at least once a month. So I lean toward a bike that I can race. In the real world, I could race either of these KTMs, but I chose the lighter 300 because it makes me want to race.
Technically speaking, the scale says the weight difference between the 300 EXC and 400 EXC is 22 pounds; but when you ride the bikes back-to-back, it feels as if the 300 is more than 22 pounds lighter. That is especially true in big bumps or quick turns. I feel the weight of the four-stroke's battery bouncing and its overall weight in tight-turn sections. I don't enjoy having to kickstart the 300, but I'll take that because it fires right up, especially for a bigger-bore two-stroke.
The 300's power is about as four-stroke feeling as a two-stroke can get; we jokingly refer to it as a three-stroke. It has a clean and crisp pull down low, something older KTM 300 two-strokes could never dial in. And from there, it will bog its way into the midrange before the power valve starts to open and things begin to get serious. It's actually a quick-accelerating motorcycle in this lower rev range, but this is deceiving because it isn't roosting, it's just hooking right along. Any time you touch the clutch, it zaps right to attention and works off the upper spread of zingy two-stroke rev, roosting, spinning and screaming. It has plenty of overrev, but for sure it loves the next gear.