ROGER DECOSTER’S 500cc SHOOTOUT

In the March , 1995 issue of Dirt Bike Magazine, Roger DeCoster tested all the 500cc two-strokes of the day. He also included the Husaberg 501, which was the only competitive four-stroke . Here are his thoughts.

 

Open-class two-strokes exist in a different world than other motocrossers. Some say that time stands still in that world, that the bikes never change and the manufacturers have given up the chase for power. The truth is that change simply isn’t needed in the 500 class–at least not the type of change required among 250s and 125s. The race for power in the 250 class is endless. A quarter of a horsepower can mean the difference between winning and losing on smaller bikes.

The quest continues for reliability with power. Open bikes don’t need more power. They already have too much. They don’t need to be more reliable. They already are the most reliable race bikes you can buy. Frankly, the only reason to change the 500s is for marketing reasons to attract buyers with the “new and improved” boasts. However, changing something that doesn’ t need to be changed is expensive and requires big sales numbers for justification. In the Open class, those numbers aren’t there any more. Not every rider is drawn to the lure of unparalleled horsepower.

That doesn’t mean there is nothing hap­pening in the Open class; quite the contrary. In Europe, the class has seen a revitalization. Spectators are flocking to the 500 GPs. Most of it can be attributed to the rebirth of the four-stroke. Joel Smets on the Husaberg and then on the Vertimati drew first blood; then Jacky Martens  won the ’93 World Championship on a Husqvarna four-stroke. Is the future of the class filled with cams and valves? Has the new-age four-stroke reached the point that it can beat all the two-strokes, all the time? The answer to the first question is absolutely. As for the second question, well, that’s what we’re here to find out.

THE BIKES

INSIDE THE 500cc SURVIVORS

The Open class can be divided into two groups of bikes these days. There are the Open bikes that strive to be like 250s­–the 260s, 300s, 360s and 440s–and there are the true 500cc maulers. This test is restricted to the big bikes. The debate over engine size being a benefit or a hindrance is an issue for another day. That leaves us with four bikes: the Hon­da CR500R, the Kawasaki KX500, the KTM 550 M/XC and the Husaberg 501C. We would like to have included the Husqvarna 610 WMX motocrosser, but it currently isn’t exported to America. The 610 WXE enduro version is too soft and heavy and wouldn’t have been a fair comparison.

HONDA CR500R

Honda’s 500 is the classic definition of the Open-class two-stroke. The bike has been around in this basic form since ’85. That was when it appeared in its present form: a 499cc, liquid-cooled two-stroke with a steel cylinder liner and no power valve. It is perhaps the simplest and lowest-maintenance motocross bike made. There are no power valves to clean, and in the unlikely event that the motor blows up, it can still be bored out and refitted with oversize pistons.

Actually, back in ’85 it was even more of a brute. Since then the bike has become a little tamer and easy to ride. Other changes have been few. This year marks one of the biggest revamp years for the 500 because it gets new suspension. Honda got tired of hearing criticism about the Showa fork and shock, so the ’95 model comes with Kayaba components. The fork is just like the unit on the CR250R, but has slightly stiffer springs (0.42 kg/mm). The Kayaba shock is much beefier than the old Showa, with a larger shaft and piston. The 500 also got a few detail changes like wider footpegs, a disc cover and a new throttle. The bike still has an 18-inch rear wheel, unlike the rest of the CR line, which went to 19-inchers for ’95. Honda knows that many of the 500s end up being used for trail riding and hill-climbing, and didn’t want to offend that crowd.

KAWASAKI KX500

Kawasaki’ s Open bike probably holds the honor of having the longest production run in motocross history. Of course, it depends on how you define “production run.” Every year Kawasaki fires up the assembly line and makes the exact same bike with virtually no changes. Kawasaki makes Honda look downright brash and reckless by comparison–the CR500, at least, has something changed every year.

Technically, though, the unchanged KX still looks more modern than the Honda. It has the Kawasaki Integrated Power Valve System which opens two small “eyebrow” exhaust ports at high rpm for better top­ end power, and the cylinder uses Kawasaki’s Electrofusion coating process. This is similar to Nikasil, a hard coating over an aluminum cylinder that has no steel liner. The coating is harder than steel and transfers heat more effectively. The only disadvantage is that it can’t be bored and has been known to occasionally flake off.

The KX uses Kayaba suspension, but the components are different designs from the fork and shock on the Honda. The sole change for the ’95 KX 500 are front and rear brake pads that we hear are new and improved. The KX is the only one of the four bikes tested to use a 19-inch rear wheel.

HUSABERG 50IC

Does this bike really belong in a comparison test of 500cc two-strokes? Sure! This is Husaberg’ s dedicated motocross bike. It isn’ t an enduro bike with the headlight removed. If the Husaberg were compared to other thumpers, it would be a slaughter. Nothing available in this country stands a chance against the 501.

One fact makes it clear how serious this bike is. On the official Dirt Bike scale, which is accurate to the nearest 111000 th of a nanogram, the ‘Berg weighs 242 pounds; that’s only nine pounds heavier than the Kawasaki and the Honda, and the exact same weight as the KTM.

The Husaberg’s engine is about as simple as a four-stroke racing  motor can get. It has a single overhead cam driving four valves. It has a Nikasil cylinder and does not have an oil pump. Crankcase pressure pushes oil where it needs to go, plus the cam chain carries it upstairs to the valves. The engine has six speeds, although you rarely use more than two or three. On the other hand, the bike only uses one radiator that goes all the way across the front of the frame. Right now, Husaberg is one of the few companies doing business in this country that uses a White Power fork. The shock is an Ohlins.

KTM 550 M/XC

Further proving that America is the land of wretched excess, this is the only country where the KTM 550 is available. This is the only bike in the test that isn’t t a pure motocross bike. KTM intends the bike to be used by anyone who wants the biggest production two-stroke on earth. Of all the particular uses that might include, motocross is the toughest. Frankly, if you go hillclimbing, the high-speed compression damping in your fork isn’ t your most critical concern. So the U.S. KTM testing staff set up the bike with motocross in mind and did much of the testing at Carlsbad Raceway near San Diego.

The fork, in fact, is identical to the one on the 250 SX motocross bike; it’ s a Mar­zocchi right-side-up fork with fairly stiff spring rates. The shock is an Ohlins, but the lever ratio and, therefore, almost everything else about the rear suspension, are unique to the 550. The KTM’s monster motor impressed the heck out of me last year, and I was hoping it wouldn’t change much. Unfortunately, Motoplat, the maker of the 550’s ignition, went out of business, so at least one change was mandated. KTM had to use an S.E.M. ignition this year, and that changed the way the bike ran at low rpm. Because the S.E.M. made the bike harder to start, KTM decided to use a Dellorto carburetor, which has a superior starting circuit to the Keihin used last year.

THE POWER 

IS TOO MUCH EVER ENOUGH?

Open bikes are all about power. Frankly, that’s why they exist; that’s why they are different. As always, though, quantity and quality are two different matters. While all of the bikes have more than enough power to get around a motocross course effectively, some just make that task easier.

HONDA CR500R

No surprises here. Honda knows how to make all its motors run great, and in the case of the CR500, the engineers had a lot of displacement to work with. First of all, the bike is easy to start by Open­ bike standards. The kickstarter is well­ shaped and prevents you from hitting the footpeg with your ankle. Also, it isn’ t located as high as those of the other bikes, so you don’ t have to be six feet tall to get a good stab at it.

Right up front, I have to say this is my favorite motor. You can put it in a tall gear and let the revs drop to a point where you can count each power pulse, then line up for the next turn, twist the throttle and accelerate like a rocket. It’ s true that the CR has gotten more mellow over the years, but still has way more power than most humans need. The power delivery is somewhat soft initially, then pulls very hard through the midrange. On top, the revs are choked off by the chicanes in the silencer. The CR is one of the quietest of the Open bikes, but still revs high enough. Unlike the other machines, when you choose to rev out the CR, you aren’t punished with horrendous vibration.

Probably the most appealing aspect of the Honda motor is how civil it is. Honda was able to make the power delivery smooth without the use of excess flywheel, and that makes the bike feel surprisingly nimble. The carburetion also is very clean. It is the only bike that never required a jetting change of any sort throughout the test. It never hiccups, misses, pings or detonates- it always pulls smoothly and consistently. The shifting is the best of all the bikes and the clutch feel and engagement are excellent.

KAWASAKI KX500

The Kawasaki comes on more aggressively than the Honda at first, then is followed by a smooth mid-range and a long top-end. In stock form, the KX should be able to out-pull the CR on top, while the CR has more punch in the midrange.

Unlike the Honda, the Kawasaki has a lot of flywheel effect. This gives the bike a clumsy feeling and slow throttle response, especially at low rpm. The fly­wheel is necessary, though, to smooth out that initial burst of power and keep wheel-spin under control. Jetting the Kawasaki is a little tough, as well. The engine runs raspy off the bottom. The first location where we tested was Sunrise Valley Raceway, near Adelanto, California, where the elevation is about 3000 feet. There, we were able to drop the needle one notch and clean up the jetting some­what. Later, on a cooler day at Yucca Valley (almost the same elevation), the bike was dangerously lean and we had to return to stock jetting. This is a very finicky motor.

The shifting and the clutch pull are good on the KX, but not as smooth as the Honda’s. The KX feels like much more of an Open bike than the CR, with more power on top, more vibration and more Open class quirks.

KTM 550 M/XC

This year’s KTM does feel a little different from last year’s model, as far as we can remember, but it’s still a very powerful motorcycle. Like the others, it has more muscle than almost anyone needs.

Last year we felt that the KTM was the most powerful of all, though, and we don ‘t feel that way this year. On the extreme bottom and the extreme top, the KTM doesn’ t run as well as either the Honda or the Kawasaki. But in the middle, it is probably more powerful than either one.

On the bottom, its power is a little soft and not quite as smooth as we remember last year’s 550 being. On top (we mean way up on top) the bike misses and won’t clean out. This might be because of an overly simple advance curve on the new ignition.

Like the Kawasaki, we had a difficult time jetting the KTM, changing it for every track. Tom Moen at KTM recommends that the main jet be changed to a 182 from the stock 190, but we ended up using a 185. We changed the needle several times, noting that each notch made a huge difference.

The motor has as much flywheel effect as the Kawasaki, but is more responsive and quicker revving. The clutch is surprisingly easy and the shifting is so-so. It’s usually difficult to shift from second to third, and the space between the shifter and the footpeg seems excessive for the average size foot.

HUSABERG 50lC

Right off the bat, you have to get into a different frame of mind to ride the Husa­berg. It’ s different.

The first difference is in starting. The kickstarter is awkwardly placed, and in order to start the bike, you have to go through a short drill. First, kick the bike through a few times with the compression release engaged. Use the choke, then kick all the way through the stroke, making sure you have started from the very top. That engages the automatic compression release. The Husaberg has very little flywheel effect for a four-stroke and so stalls easily. You might want to turn the idle up for several reasons: the bike starts more easily, it stalls less often and it has less engine braking. Riding the bike with a fast idle might take some getting used to.

What about the power? The Husaberg isn’ t as fast as the two-strokes. Having said that, we must point out that on some tracks it matters, on others, it doesn’t. If the course has a long, sandy uphill, the thumper’s motor will be dragged down where the other 500s will never stop accelerating.The 501 has good, smooth power right off the bottom-maybe as much as the Honda – then has a long midrange where not that much happens. This is the rpm range where the other machines do their most impressive work. On top, the Husaberg revs out surprising­ ly well, enabling you to stretch one gear a very long time. Shifting is easy, at least through fourth gear. I can’t say that I ever tried fifth and sixth, although it says that it’s a six-speed right on the cases. I’ll take Husaberg’s word for it.

The best thing about this motor is that it makes you want to go fast. The awesome sound, the wide powerband and the smooth delivery make riding fun. And when riding is fun, you tend to try harder.

The clutch is a little hard to pull, which is more of a problem because of the motor’s propensity to stall- you have to enter some turns with the clutch in. Chuck Sun (’80 National 500 MX Champion) is now working with the Husaberg importer and tells me that the 350 clutch springs make the pull much easier and don’t cause slippage. 

SUSPENSION

THE WAR OF THE WHOOPS

Nothing is more horrifying than 60 horsepower when it’s bolted to bad suspension. On an Open bike, you go faster and hit things harder than on any other bike, so the fork and shock take on an extra significance.

All of my suspension evaluations are, quite naturally, for me. I weigh about 165 pounds and tend to go around bumps whenever I can find a line. I rarely leap from tall buildings, although I frequently land on the faces of jumps that Mike LaRocco or Jeremy McGrath might jump over. Over the years, though, I’ve found that in most cases, good suspension is good suspension, no matter who does the riding.

HONDA: THE KAYABA SWITCH

Most riders believe that we can finally answer the zillion-dollar question this year. Can Hondas have good forks? Kaw­asakis and Yamahas have good forks made by Kayaba, so doesn’t that mean that the CR500 will finally have a good front end? Well, the ’95 CR proves that Honda can have a good fork, but not a great one. The new Kayaba fork might be a slight improvement, but it’s still not the best in the test.

Most of the improvement can be traced to the stiffer fork springs. The Honda has the stiffest fork of these four, so it can be pushed harder on a rough track. But there’s no magic here. On smoother tracks like Glen Helen, the Honda is harsh and has to have the compression damping reduced.

In the rear, the Honda scores much better. In fact the CR consistently had the best handling rear end on each of the tracks. Like the front, the CR’s rear end is a little stiffer than any of the others and could be pushed to the limits and a little beyond.

KAWASAKI: STILL CUSHY

Kawasaki’s interest in off-road racing has doubtlessly influenced its suspension development. The one track where the KX front end truly excelled was Yucca Valley. That track has enormous sand whoops; in other words, it’s a lot like a desert race. At the other tracks, the KX fork seemed a little soft, although it always gave the front end a well-planted feel. My biggest complaint is that the fork bottoms harshly unless you have the compression damping perfectly adjusted. For the settings I used on the various tracks, refer to the chart in the test. For hard motocross, you can expect most KX riders to go up on the spring rate to a 0.41 kg/mm.

The Kawasaki rear suspension ranks second best in the shootout. Only the Honda tracks better and straighter. Again, the KX is a little soft, set up for desert rid- ing.

KTM:THE MARZOCCHI/OHLINS COMBO

Last year, the KTM couldn’t be taken seriously as a motocrosser because of its ultra-soft, off-road suspension. In fact, it was even too soft for off-road riding. Now with the new Marzocchi fork and Ohlins shock, it takes a quantum leap forward. There’s absolutely no doubt: the KTM’s Marzocchi fork is the best of this bunch. By far. It absorbs the low-speed stuff even better than the soft KX fork. And it handling big landings even better than the stiffer Honda fork. The Marzocchi has an excellent feel when bottoming. It is hard to find a condition where the KTM front end isn’t excellent. If that ever happens, it’ s on sand tracks where the fork is so smooth that it’s hard to tell if the front wheel is on the ground or in the air. I also noticed that the fork overhang did touch the ground in some deep ruts, and occasionally there was some torsional flex.

In the rear, the KTM isn’t as impres­sive. Compliance is good on small bumps and holes, but the Ohlins shock tends to go through all of its travel rather quickly on big bumps. It could  use either more high-speed compression damping or a stiffer spring rate. This is, technically, an off-road bike as much as an MXer, so we would be surprised if it were perfect right out of the box.

HUSABERG: THE WHITE POWER/OHLINS COMBO

Husaberg, like Kawasaki and KTM, must have had trail riding in mind somewhat when setting up the suspension. The fork feels smooth and cushy, but is too soft and dives on MX tracks. Even with the adjuster turned all the way in, the White Power fork bottoms harshly.

Ohlins helped Husaberg redesign the rear suspension linkage this year, and the rear end is vastly improved over the model I rode last year. Fast riders who like to jump will still have to revalve the shock for more high-speed compression damping. The Husaberg has some clearance problems in the rear end, too, and the honking sound of the tire hitting the rear fender can be heard all around the track.

ON THE TRACK

PUTTING IT ALL TOGETHER TO WIN RACES

Power and suspension are two big factors in the race winning equation. But how does everything fit together on the track? Do all the pieces fit together and make a whole that is greater, or smaller than their sum? As you might guess, in the Open class, things are a little different than anywhere else.

HONDA CR500R

The Honda feels like a motocrosser should feel. The handlebar, footpegs, levers and shifter are in the right spots. The seat isn’t too hard or too soft and the CR also is the narrowest of the four.

The list of things that the Honda does better than the other bikes goes on. It’s the lightest feeling and most nimble. It’s the least tiring of the two-strokes. And it turns fairly well, especially in wide turns. Actually, I think that the CR500 from ’89 was better in the turns, but Honda changed the steering geometry in favor of more stability. And I need to point out that none of these machines are particularly easy to handle in tight turns. Big engines create a lot of gyroscope action that makes them very stable, but very difficult to turn. Still, I have ridden 250s that don’t turn nearly as well as the big Honda, as long as the corner isn’t super tight. Part of the credit probably goes to the smooth low-end power.

Coming out of the turn, you can get on the gas early as long as you exercise a little throttle control. There is still a little head shake at high speed over choppy terrain, but it’s nothing to make you roll off the throttle. The days of absolutely horrifying Honda head shake are mostly behind us. The fork adds a little to the nervous feel by transmitting small impacts through to the bars. You don’t run into a limit when you ride the CR. You don’t have to slow down because of anything the bike does. In stock form, the bike can be ridden by beginners all the way up to Pro-level riders.

KAWASAKI KX500

The KX is the most stable bike of the bunch at any speed. It has virtually no headshake and holds a line extremely well. It is also the best bike in tight turns–even better than the CR. This is a rare combination in a motocross bike, good turning and good stability.

The power of the KX is sometimes hard to use in low traction circumstances. The engine is a little rough off the bottom, so the Honda might be able to get on the gas a little earlier and get a head start down the next straight. The KX feels like a long, big machine; the rear end feels like it is way behind the rest of the bike, and this creates a lot of wheel-spin. Ergonomically, the Kawasaki is good, but not quite as nice as the Honda. The bike is a little wide, the handlebar has an unusual amount of rearward sweep, and the shifting, the brakes and the clutch all are second best.

In a technical sense, the Kawasaki is an excellent motocrosser. It has good handling traits, excellent power and good suspension. Overall, though, it’ s not a very fun motorcycle to ride. It vibrates, the motor is hard to use and it’s the most violent of the four bikes. It’s a machine made for good lap times more than good times.

KTM 550M/XC

The riding position feels good on the KTM until you start trying to cut fast lap times. The seat is very hard and there’s a bulge on the exhaust side that interferes with the rider’s leg when he leans back. When the rider moves forward, the pipe melts his boot.

On hard, rough tracks, the KTM’s fork gives the bike a big advantage, but if the whoops get really big the rear end takes that advantage away. One aspect of the 550 caught me by surprise, though. With the change in the fork there also was a change in steering geometry. There seems to be much more trail and the front end has a lot of self-centering force. Now the bike doesn’t want to tum unless you are very forceful.

You would think that this would make the bike more stable, but that’s not the way things turned out. Head shake doesn’t strike often, but when it does, it’s nasty.

Racing the KTM competitively would be easy, as long as you paid attention in a few areas. You might have to revalve the Ohlins for more high-speed compression damping and you would have to clean up the jetting. We used pump gas, but race fuel might be necessary with the leaner jetting.

HUSABERG 501C

The first impression you get riding the Husaberg is that it’s a lot lighter than expected. This proves that four-strokes don’t have to start off with a weight disadvantage. In fact, the Husaberg actually feels lighter than the Kawasaki, although the Honda still wins in that category.

Riding the Husaberg requires a differ­ ent mindset-you don’t quite have to relearn how to ride a motorcycle all over, but you do have to work on a different technique. The bike is very difficult to tum despite the light feeling. It’s not as bad as the KTM, but not nearly as good as the other two. This is made worse by the engine’s knack of stalling- to be safe, you have to do all of your heavy braking with the clutch in.

As a result, the bike gives away a little to the CR and the KX in the turns, and then it gives away a little in acceleration where there’s good traction. I suspected that my lap times were slowest on the Husaberg at our high-desert test track near Phelan, California. To confirm, I was timed on four consecutive laps, first on the 501, then on the CR. The Husaberg was, indeed, a few seconds off the pace.

This disappointed me because I would rather ride the Husaberg than most other bikes. Maybe it’s just that macho sound, but the Husaberg is a blast! It’s just that, in order to win, you would have to design a track especially to suit the bike–moderate chop without big jumps, long straights, poor traction and sweeping turns. None of the tracks we used fit that description.

A WINNER

It’s easy for me to pick a winner among these four. The Kawasaki is effective without being fun, the Husaberg is fun without being effective and the KTM is somewhere in between. That leaves the Honda as the most well-rounded race bike of the four.

Does this mean that four-strokes can’t be competitive in motocross yet? Hardly. Husaberg has overcome all the hard obstacles–the 501 is light enough to win races already. All that remains is a little fine tuning.

Comments are closed.