Posted on Wednesday, February 05 @ 23:53:51 CST  ![]()
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What qualities determine the best four-stroke motocrosser? Is it the highest performance? The lowest weight? Is it the bike on which Experts can cut the quickest lap times, or the one on which Novices feel least intimidated? Should you just throw up your hands and go with the choice of magazine editors and test riders?
Article compliments of Cycleworld.
With these bikes, it's easy ? almost too easy ? to pick a winner, but harder to explain why. When all the machines perform to a level that can't be explored by most riders, it's nearly impossible to put your finger on what makes one better than the others.
So this time around, instead of a rush-to-justice, slam-bam-thank-you-ma'am-style of shootout, Cycle World decided to go the extra mile. We rode all three contenders ? the Honda CRF450R, KTM 520 SX and Yamaha YZ426F ? at as many different venues as possible, including everything from natural-terrain outdoor motocross courses to the very same Supercross track on which the Pros competed at the U.S. Open, inside the MGM Grand in Las Vegas. We pounded all of the bikes hard ? especially the new Honda ? to see if we could untie any loose ends. Then we stripped them down, weighed and measured them, and took a close-up look at what makes them tick.
In the process, some of the bikes' traits were validated, while others ? to say nothing of the hype printed in ads ? were squashed. The exercise left us with a solid backing for our riding impressions, and an interesting insight into the different methodologies employed by each manufacturer to build a competitive Thumpercrosser.
Yamaha started what is now history by unleashing the 1998 YZ400F, the first modern production four-stroke motocrosser that was directly competitive against two-strokes. The 2002 YZ426F is the same basic bike, heavily revised. It was never designed to be ? in this order ? a four-stroke motocrosser, but rather a motocrosser that used a four-stroke engine.
Yamaha's engineers considered the rules-mandated displacement advantage ? i.e. 550cc four-strokes were eligible to compete against 250cc two-strokes ? and realized that not only was a big four-stroke's power output superior to that of a smaller two-stroke, it also had a longer power spread, plus increased torque, compression braking and durability. The four-stroke's negative qualities, such as hard starting, heavy weight, frequent stalling and added complexity, all took a back seat to the hype over the "Four-Stroke Revolution," and this momentum carried over to the YZ400F winning Cycle World's Motocross Bike of the Year award in its first attempt.
Over the past five years, Yamaha has focused mostly on reducing the YZ's weight, but also on increasing power, and improving throttle response and suspension action. Looking at the 426 today, you can see its age, and imagine the burden the designers had to bear in being the first to build such a bike. The engine was overbuilt in terms of oil and coolant capacity, because it had to be; if all the first-year YZ400Fs had blown up, who'd be stoked on four-stroke moto-crossers? You can thank Yamaha not only for starting the trend, but for keeping it going.
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KTM was right there at the start, but opted to wait a couple of years and get its four-stroke MXer right rather than rush it and get it wrong. This meant that while the Austrian company settled for second in delivery time, it one-upped its Japanese rival in one critical area: weight. Nearly 10 pounds lighter than the Yamaha the first year out, the KTM 520 SX was equipped with a simpler sohc, four-valve engine with wet-sump lubrication, its added displacement equating to added power, which it flaunted quite nicely.
And now comes Honda with a bike that is a study of its competition, melding all of the best characteristics to create the next step in four-stroke motocross evolution. But that said, perfect on paper doesn't always equate to right on the racetrack. Can a first-year effort surpass proven designs? That's what this comparison is all about.
Starting with starting: Used to be that four-stroke Singles didn't start, at least consistently. Then it got to where each bike had a "drill" that needed to be followed. Well, welcome to 2002, and forget about the routine 'cause the kick-and-go Thumper is here to stay! At least red and orange ones: Hot or cold, the KTM and Honda fire right up with one or two kicks. After a stall or a crash on the Honda, you simply pull the hot-start lever and kick. And the KTM starts even easier; one smooth kick is all it takes. Yamaha riders still have to pull the hot-start button, squeeze the decompression lever, find top-dead center and then kick, which now seems like even more of a pain. Watch for hot-start lever-actuation upgrade kits for YZ owners.
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Next, let's talk power. For the moment, avoid looking at the accompanying dyno chart, it will only confuse you. On the track, the KTM is the king of power no matter how you slice it. Provided it can get traction, the 520 is gone to the tune of three to four bike-lengths on the average MX start straight. It isn't the quickest revving, but it has the meat to make the powerband seem longer than it is. The Honda and Yamaha are left to fight for scraps, which they do ever so closely. The YZ has more bottom-end snap and a quicker revving low-end snarl than the CR. It then goes into an almost bland blur of seamless power delivery, right up to the point where the rev-limiter kicks in without much sign-off to warn you. Forty-seven horsepower isn't bland, it's just that the delivery is smooth and progressive, hooking up and getting the job done without fuss.
The Honda has more of a Thumper feel to the bottom end, a certain flywheel effect, and comes on a little smoother than the Yamaha or KTM, seemingly holding the power back till you're good and ready for it. But when it comes alive, it really gets with the program, making the 426 feel tame in the midrange. Up on top, there is more power than most will ever use past the start straight. If you like to rev a bike, then you will prefer the YZ. Short-shifters will prefer the CRF, as it signs off on top, telling you to shift before you hit the rev-limiter. The tighter the track, the better the bottom end of the Yamaha comes into play. The more flowing and less tight, the brighter the Honda shines. The KTM frankly doesn't care and roosts everywhere.
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Examining the dyno chart, it's amazing to note that the Honda and KTM produce about 49 horsepower. This reveals what an irrelevant figure peak horsepower is for motocross. Surely, that number looks good in the sales brochures, but eyeball the torque curve and you'll see the advantage the KTM possesses, particularly between 3500 and 6000 rpm, where it holds a solid 5 foot-pound advantage. And in spite of the Honda's obviously more powerful engine, the Yamaha is able to keep pace by running at higher rpm.
On to handling: Here is where the Honda really shines. It has a very predictable nature that is never flustered by differing track conditions, roughness or soil types. It has a very light feel, especially for a Thumper, most noticeable while turning. It flicks around in the air almost like a two-stroke, and bounces through whoops just the same. The footpegs are high, prompting some riders to feel cramped, though none of them felt as though they couldn't move around on the bike. Every one of our testers picked the Honda first in handling. The CRF's suspension plays a large role in the bike being so user-friendly. Honda obviously spent a lot of time finding a happy medium in settings, aggressive enough to satisfy hard-chargers yet plush enough for the slower guys. What was strange was that once we got our good settings, we never changed them from track to track!
The Yamaha has a very aggressive handling nature. It plants the front end and goes just where you point it. The bike has a stiff feeling, mostly due to the suspension, that lets you feel the ground more than the others. When you hit whoops, you'll definitely feel them, but the bike will never wallow and let the weight take you along for a ride. The harder you hit things, the better the YZ likes it; this is the only bike here that makes no sacrifices on a Supercross circuit. Plainly, Yamaha set out to build a bike for today's more aggressive tracks and riders. With the YZ, setup is more critical that on the other bikes, but it pays off when it's right.
For the KTM, handling and suspension are the areas in which there was the most improvement from last year. With the addition of a 48mm fork, the 520 has gotten a new lease on life, and throws about 90 percent of its former stability issues out the window. With a longer shock out back, the SX has a newfound ability to work at both soft and hard ends of the spectrum, without robbing Peter to pay Paul. Bottoming resistance is excellent, as well.
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The biggest bike here feels like it will turn under anything, but you have to be careful; riding the SX this hard takes quite a bit of throttle control. As rpm increases, so does the perceived weight of the bike; it can go from a puppy dog to a big, barking monster in just a half-turn of the throttle. Ditto for jumping: Off-throttle, it's like a 125, but gas it and it's an Open-classer. The KTM uses quite a bit of travel to get the plushness that most riders need, and so the suspension strokes farther than fast riders want on steep jump faces. Overall, the 520 seems able, with some set-up work, to be the best in any condition, but the standard settings allow it to work everywhere without sacrificing much ? like a stocker should.
On to the quirks that set these bikes apart: First come braking and compression braking, which on four-strokes go hand in hand. The Honda has the best brakes and the least compression braking, the engineers wanting to mimic a two-stroke as much as possible. The KTM has the strongest brakes and the most compression braking, but you'd better be careful how you grab those brakes ? especially the front ? because this is what "works" brakes feel like! The Yamaha fits in the middle, with weaker-but-good-feeling brakes and a fair amount of compression braking.
Throttle response is another area of concern. Whacking open the throttle or messing up with the clutch can lead to the four-stroke racer's biggest fear: stalling. The Honda has the amazing trait of zero hesitation; you can turn the throttle with reckless abandon and the motor will respond. The Yamaha and KTM take a certain amount of finesse at low-low rpm, and for the inexperienced rider, this can be a real issue. Even so, we never had problems stalling any of these bikes.
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Finally, more on the weight issue: All three of these bikes are worlds lighter than Thumpers used to be, but the Yam-aha is an older design, and carries a few extra pounds in the wrong places. We took all of the bikes completely apart, and while the 426's main parts weren't that much heavier, there were just more parts! Also, the Yamaha's hardware was quite a bit heavier than on the Honda or KTM. The YZ's dry-sump motor stores a good portion of its oil high up in the frame, and the radiators hold a bit more coolant higher than on the CRF. Little details make all the difference.
The KTM is a study of how a bike can be heavy and feel light. Though it boasts a 5-pound weight savings over the Yamaha, it feels more like the 10-pound lighter Honda. How? Mass centralization. The bulk of the KTM's tonnage lies in its motor, and specifically in its crank and tranny ? the spinning stuff. That's why it feels heavier with rpm. The frame is very light ? there isn't even a head-stay ? and maybe a bit flexy, adding to the light feeling. An incredible amount of attention was paid to the KTM's hardware, with dished head fasteners, tapered engine-mounting bolts and a complete lack of unnecessary parts. But paradoxically, the 520's linkageless PDS rear-suspension system isn't that much lighter than the linkage-equipped bikes, though we have to admit it is easy to work on.
Surprising is that the Honda is a whopping 15 pounds lighter than the Yamaha, but its motor and frame only account for 2 pounds of that difference! It comes down to small items such as brake systems and coolant capacity. Compounding this is the fact that the CR's mass is, as on the KTM, well centralized. Honda's engineers wanted to make a statement here and they did. Curious is the fact that the CRF's titanium header pipe is just 1 ounce lighter than the YZF's stainless piece, while its entire exhaust system weighs nearly a pound more than the others'. But bonus points to Honda for keeping the sound down, and double bonus points to KTM for being even quieter at a lower weight.
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We're not picking second place here, and we're not telling you which bike is best for you ? it's up to you to decide. If your style is to get the holeshot, pull out a lead and cruise around in front, then the KTM is tailor-made for you. Unfortunately, due to new rules limiting four-strokes to 450cc in the 250cc class, you'll have to fight it out in the Open, Vet or Senior classes now. But this suits the 520's style; it really doesn't like to be ridden aggressively, but prefers fast-cruise mode. We can't tell you how many times one of our testers got into a race on the KTM, only to get aggressive and fall behind. Then, as he relaxed and got in a groove, he'd catch back up and pass the guy he was racing with!
The Yamaha is all about aggression. With its responsive low-end power, it craves tighter tracks, and sings a furious rpm song for those mad enough to ride it like it wants to be ridden. And when you're riding it like that, who cares if it takes more energy? Part of the reason you ride is to stay in shape, isn't it?
Like we said at the start, it's easy to pick a winner. And for once, it's easy to explain why: Honda's market-research guys spent the last few years canvassing the country, asking Yamaha and KTM owners every question in the book in order to feed the engineers the information they needed to build an even better four-stroke motocrosser. The result is a bike that is flawless for most riders ? particularly if they've come off a CR250, because the new Thumper carries over most of the two-stroke's traits. The only complaints were from riders who wanted a bit more bark off the bottom ? most likely only a muffler swap away ? and from those four-stroke faithful who wished for a bit more compression braking. The Honda is, like the Yamaha was in winning our four-stroke comparison last year, very "vanilla" in this crowd, simply getting the job done without much excitement ? although just riding this bike was excitement enough for most of our testers.
But now that Honda has shown its cards, and is basking in glory, we can only wonder: What lies in wait?
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