The Ultimate Motocross Bike - Dirt Rider Magazine

The 250F/></a>
<p class="wp-caption-text">The 250F</p>
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<p>Easily half of the correspondence arriving at the palatial Dirt Rider offices asks some variation of “What bike should I buy?” The underlying theme of this flood of paper and e-mail is this: There must be one ultimate motocross machine, and if anyone knows what this Holy Grail is, it should be Dirt Rider. And since we must know, why are we keeping it a secret?Truthfully, there’s no conspiracy here. Even though we were 98 percent sure we knew the answer to this question, we thoroughly tested the theory before typing it out. We gathered a cross-section of bikes and riders that we felt would be representative, then dive-bombed three completely different tracks, backing that with the months we’ve spent on the machines leading up to our comparison. We tallied lap times, subjected the machines to the unwavering eye of the radar gun and the ruthless judgment of our incredibly accurate scales. Finally, showing no mercy for clutches, we flogged the bikes through 50 or 60 full-on motocross starts with pro and intermediate riders aboard.For bikes we chose a Honda CRF250R, a big-bore KX250F fitted out with an Athena 290cc kit, a KTM 250 SX and a Yamaha YZ450F. We selected the bikes more as a rainbow-colored collection than for any other reason-a well set up rainbow at that-yet made it clear to our riders that we weren’t testing the specific bike but rather the type of bike. All were set up for a 170-185 pound intermediate rider with some tweaks our staff has come to like. The KTM 250 SX with a pricey set of hlins suspension components could be considered the most modified, and the 450 with just an Akrapovic exhaust and some Cycra plastic as the least modified. For riders, we gathered novices to pros with ages ranging from 19 to over 50, though most of the riders were 20-somethings.We visited Milestone Ranch MX Park for a twisty mix of loam and firm dirt and a varied layout on a couple of its multitude of tracks. Next we hit Racetown 395 on an open practice day for fast and rough with high-speed jumps. Finally we tackled the tight and twisty elevation-enhanced clay of Piru MX. All told, we had plenty of variety to reach a decision. To keep the answers real-world, the riders noted whether a given bike was a competitive race mount, one they would choose for fun and whether owning/racing it would be cost-effective.<strong>The 250F</strong><br />There’s no question that a 250F has the fun factor once reserved for 125cc two-strokes but in a package that has more boost and far less fussy power delivery. A 250F is unbelievably light for what it is. Just a few years ago 125cc two-strokes were within five pounds of current 250Fs. The power doesn’t get out of hand easily, despite horsepower numbers reserved for 250cc two-strokes in the 1990s. That may seem like ancient history, but those 250s had power output and delivery that essentially killed off the 500cc two-stroke.Riders in Vet age classes wonder if a 250F would be competitive despite most of the class being on 450s. For young riders moving up from minicycles, they are the logical stepping stone. But now when 250Fs and 250cc two-strokes race together, it can be confusing. After you reach 165 pounds, though, the choice is even muddier. For most the decision came down to rider weight and whether they compete in age classes. In answering the question, “Would you be competitive racing this bike at your riding level?” we used our CRF250R slightly modified from our April ’08 “Fine-Tuning” story, but turned it back to red with UFO plastic and Factory Effex graphics and earned these remarks:”I could race it if there were other fat old guys on 250Fs. Against kids or light old dudes, no.” “If I rolled up to the line on a stock 250F, I guarantee that I’d be outpowered by a couple of rich kids.”"Since a Honda CRF250R is my current practice and race bike, I’m really happy with the bike. The only downer is on fast courses where I wish the bike had another gear.”"I’d be less competitive in the beginning of motos and more competitive at the end. This bike allows me to ride longer at a faster pace without wearing myself out, but you can’t get a good start in the Vet class.”Surprisingly, when asked about the bike they would ride for fun if they didn’t race, Vet intermediate Jesse Ziegler and pro Ryan Orr were the only ones to vote 250F. Jesse was persuasive in his arguments. “These bikes (250Fs) are my favorite moto toy. They require me to be on my game enough to keep it interesting but allow me to be off my game and still keep me smiling when I’m lazy. I don’t have to be a technique master to make the motor work, and if I get a little out of shape with the throttle hand, they don’t leave me with stained shorts. I love 250Fs. I just wish they’d go down the start straight as fast as a 450. On a lap-time test, I’ll always be able to throw down a few fast ones with a 250F. But for racing, when you incorporate the start, the little guy isn’t quite there.”Here are the key points if you’re considering a 250F. No matter what the skill level, weight or even age of the rider, the lap times for the 250F were always close. During our practice starts the 250F was usually at the rear of the pack, but not as far back as you’d expect. For classes where displacements are mixed, you need to ask yourself some tough questions. Do you love a challenge? Are you riding for fun or to win? Do your normal tracks have deep sand or loam that offers maximum traction? If so, you’d better be a light rider. Are you racing/riding where there are multiple lines in the corners? 250Fs prefer a flowing line around a track. Riding a 250F will bump the corner entrance speed of most riders, but that’s useless if bigger bikes are clogging a one-lined track.In the hands of a light, aggressive rider, a 250F is a weapon against any size bike in the right conditions. If you do everything perfect on the start, you can get to the first turn at least in the same neighborhood as 450s, but you won’t be there first. Is the 250F the blanket “best bike”? No. Not because it isn’t good or fun, but because it has limits.
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The big-bore 290F is trying to save the weight and serve the power. It works./></a>
<p class="wp-caption-text">The big-bore 290F is trying to save the weight and serve the power. It works.</p>
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<p><strong>Big-Bore 250F</strong><br />We selected a big-bore to represent itself and the ultramodified 250F for a variety of reasons. For one, the performance increase a big bore brings is a great dollar value, and the power is added in the very parts of the rpm range where a stock 250F is weak. Also, nearly any medium-skilled mechanical type can change the piston on a 250cc four-stroke, and it’s no harder to install a big-bore kit. All of the 250F models have a variety of bore options with the Honda being the most limited as far as choices go, since the cases won’t accept a larger sleeve without modifications. And as long as the rpm ceiling and compression are unchanged, a big-bore should be reliable and run happily on pump gas. A big-bore might even extend valve life, since you aren’t forced to scream the engine as much. This KX-F, like the CRF250R, was tuned a bit already. It carried the Pro Circuit pipe from a previous test, and we added PC’s revalved suspension to the tiring stock setup. An R&D Powerbowl float bowl with its externally adjustable leak jet cures the off-idle fussiness in the carburetion, a necessity with a big bore. Unlike other hop-ups, this larger piston doesn’t diminish the fun character and ease of riding that makes a 250F a blast. The bike doesn’t acquire a heavy feel, and you actually clutch it less.This Athena 290 kit has a plated aluminum bore like a stock bike, and it certainly feels meaty and strong on the track. Surprisingly it doesn’t feel as strong as the radar gun says it is. It just feels easier to ride, with more torque way earlier in the rpm range. Mistakes are easier to recover from, and you shift a bit less. You still end up keeping the mill singing to do serious business, but life isn’t quite so frantic. Nevertheless, the radar gun shows a clear advantage in the lower part of third gear during a roll-on-not just against the 250F, but running with or slightly stronger than the other bikes, credit that to it just being at the limit of traction, not beyond it as the 250 two-stroke and 450 were. During the full acceleration run the 290 is clearly ahead of the 250F and closer to the other bikes. Yet if the track surface is deep, sandy or muddy, a mod 250F is still between 5 and 15 horsepower behind a two-stroke or a 450.In terms of weight feel and how much energy the bike takes to throw around, the 250s-two- or four-stroke-have a weight advantage of 9 to 11 pounds over the YZ450F, and some other 450s weigh at least another 4 pounds. While the difference may be relatively small, a 450, due in part to the power and adding the extra inertial forces, feels a lot heavier.Part of the purpose of this test was to see which bike got around a track fastest, and the two little four-strokes are rarely off more than a second or two a lap when times are averaged. It didn’t matter whether the rider was light, heavy, young or older. Expert Chris Dvoracek is a unique advocate of this bike. In the grand prix series he races, 250cc machines compete together regardless of engine type, so the extra boost is attractive, though a 290 is downright illegal. “Honestly, this is my dream bike: a 250F that has that extra little thump. It’s a bike I’ve always wanted but have never gotten. With the extra power I could make a little mistake on the start and still get a top-five start, whereas that would be impossible on a stock 250F.” But getting this level of additional power while still keeping the displacement in check is expensive and maintenance intensive.So what it comes down to is can you capitalize on the corner speed and lightness of the bike? Another huge factor is whether you can pass. Even with the 290, you are merely going to be close on the starts most of the time, only luck or perfection could catapult you to the front of 450s. Passing is easier on a bike like the KX290F, but you’ll still have to work for it. The thing is, working hard on this 290 is a bunch of fun.
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<strong>Jesse Ziegler</strong><br />Holdouts rejoice-the 250 two-stroke is very competitive and really fun./></a>
<p class="wp-caption-text"><strong>Jesse Ziegler</strong><br />Holdouts rejoice-the 250 two-stroke is very competitive and really fun.</p>
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<p><strong>250 Two-Stroke</strong><br />There’s no question that a 250cc two-stroke has a lot to offer. In addition to lightness and maneuverability rivaling or even surpassing 250Fs, there’s the power. A strong-running stock 250 makes peak power in the ballpark of a stock 450. This is when even good riders can’t effectively use all of a 450′s power. This ballpark is a happy place to be.Consider the parts of motocross one at a time. First, there’s the start. A two-stroke can get a start close to or beside 450s, and you may even beat them. This is more likely on short starts than long, high-speed or uphill pulls. Once on the track, a 250 allows great corner speed and control in ruts. In rapid direction changes, a 250 flicks side to side with equal or less effort than a 250F and much easier than a 450. Then there are the jumps. You think there’s a reason that nearly every freestyle jumper on the planet rides a two-stroke? Typically they offer great control in the air thanks to light weight and a smaller gyro effect from the engine. And they start easily without much thought. As far as lap times go, a variety of riders-in terms of skill and age-were able to lay down hot laps even on the KTM, a bike that still suffers from some of that “it’s just different” syndrome. We have a killer suspension setup on our bike and switched between stock and FMF exhaust during our testing.Still, a lot of these lap times are undoubtedly slower than they could be as riders struggled to get used to the different two-stroke feel. As good as a modern 250 is, it’s quite different from a four-stroke. The power comes on more suddenly with more hit, and below that hit the roll-on is less effective than even a small-bore four-stroke. A thumper lets you get a bit lazy, a little sloppy and it covers up for you. A two-stroke demands the correct gear for the situation, whereas a four-stroke has nearly twice the length of usable power in every gear. And don’t forget the lack of compression braking; you’ll need to remember how to carefully use that rear brake again. Jesse clearly pointed this out: “I couldn’t get comfortable on the two-stroke immediately. It lights up like a firecracker, and the bike is so light that I find myself catching up to it worse than when on most 450s. If it was my only bike, I’d adjust and start to enjoy it to a level, but in a straight-up comparison it doesn’t come close to the easy power and handling of a four-stroke.”But most of us used to ride two-strokes, and if you ride one exclusively, you’ll automatically use its strengths to advantage. But in a comparison like this, where riders had to jump from four-strokes to the two-stroke, the differences are highlighted.You cannot be lazy. You not only need to be in the proper gear for a turn, you’ll need to grab a shift immediately after exiting the corner as well. The same is true on jumps, especially to get the snap you want on a steep jump face. A two-stroke makes a lot of power, but it produces boost over a shorter rpm range than a four-stroke-even a 250F. If you look at the radar runs, wherever the line goes up steeply the bike is pulling hard. You’ll see that there are places the 250 is accelerating more violently than the 450. For some riders that isn’t an issue, but for others it tires them out and causes early arm-pump.But for a low-maintenance, high-fun race or moto-playbike, a two-stroke is still a winner and perhaps has the highest smile-per-dollar ratio. A perfect example is Jimmy Lewis. This KTM 250 SX is his moto bike for the year, and it’s set up for him and his riding style. “This bike is completely competitive in the longer motos that Vet pros run,” he said. “I can ride it hard and stay aggressive, but I don’t get whipped like I do on 450s. Most of the time I can get a good start against big bikes, too. For sure a two-stroke is the most cost-effective to own of the bikes in this group. As good as they are stock, there are decent ways to make the bike better with cash. I have to pay more attention in the first few laps on a 250 two-stroke, but later in the moto it’s easier for me to keep on my pace.”
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The 450
OK, so all you conspiracy-theory guys are right. Two-stroke 250s smoke 450s, but the factories want to sell more parts. And, yep, none of those factory teams or top riders tested back-to-back; they just switched to 450s because they had to. Are we square now? Fine.Now that those guys are satisfied, let’s look at some facts. For riders at a National level there’s no way to compete equally on a 250cc two-stroke against modern 450 motocrossers. The actual weight difference is small-the lightest bike here is 228 with a full tank and the Yamaha tips the scales at 239. But a 450 makes more and smoother power over a longer rpm range, seemingly getting the power to the ground more effectively. The YZ is definitely strong here, and adding the Akrapovic pipe certainly helped it out. Current 450s are easy to start, handle well and have the absolute latest in suspension and chassis technology. They are basic to get starts on, effortless to learn new jump sections with and are usually easy to care for. Any local guy should get a year of hard racing without looking in the engine, and weekend warriors perhaps much longer.If you thrash the clutch, hammer the rev-limiter or let the bike ingest dirty air, like any four-stroke, you will have expensive problems. Sure some guys have had unusual, catastrophic failures and the resulting repair bills can give Bill Gates indigestion, but most dirt riders ride these things for many trouble-free hours. When things do wear, it’s usually the valve train, and incomplete repairs or lack of checkups add to the bikes’ poor reputation.In all of our empirical, measured tests the 450 pretty much came out on top. It didn’t matter whether the track was tight or fast, rough or smooth or what level the rider was at. The 450 topped the roll-on, the full-throttle drag race, tied or was fastest for almost every rider’s lap times and was out front on nearly all the starts.If you want every advantage when you’re racing, you want a 450. There is a dark side. A 450 is hard to hold onto and gets harder as a track grows rougher or more technical. It chews through tires and chains, and it just plain feels heavier and harder to throw around in turns and in the air. Despite what you saw RC do for years, if you’re small or light, a 450 can be more than you bargained for as well as genuinely difficult to get the suspension dialed. A bike this fast demands absolute throttle control, and when you’re tired, that level of control is elusive.Choices
Does this mean that a 450 is the bike for every rider? No, just as close as it gets at the moment. But that doesn’t mean it’s the correct bike for all riders and certainly doesn’t guarantee it being the most fun or effective for your conditions and riding style. Mixing 250 two-strokes and 250F four-strokes in amateur racing has revitalized mixing gas. And increased sound regulations has helped the popularity of two-strokes surge in Europe. If you like to ride wild and loose, you have no business on a bike that is 450 fast (or 250 two-stroke fast, for that matter) unless you have buckets of skill and experience. Is your joy of motocross in railing ruts and flinging the bike around? Are you a bit sloppy with throttle control? Same answer. Imagine an international “NO” symbol across all 450s. Don’t want to work on your bike much? You’re right, two-strokes are better. The great thing about modern motocross is having amazing choices. The lap times prove all these bikes are viable, fun and winning choices. But on average, a 450cc four-stroke is the big dog on the track. So this settles the bike question. Whether you want to follow the crowd of big dogs is a question you’ll have to answer for yourself.For some of the straight-up opinions, more photos and dirt on the bikes, check out www.dirtrider.com.Weight (ready to ride, tank full)
CRF250R: 228 lb
KTM 250 SX: 230 lb
KX290F: 230 lb
YZ450F: 238 lb