Honda Cr500r

HONDA CR500R

CYCLE WORLD TEST:

BECAUSE JUST HORSEPOWER ISN'T ENOUGH

There's a Universal Truth concerning motocross riders in general, and Open-class riders in particular: They want horsepower. More power, perhaps, than they need or can even use. But they want it nonetheless, and that leads to a second Universal Truth: The manufacturers are delighted to give the people anything the people want. The proof of that can be found on the start line of any Open-class motocross. When the gate drops, there' s enough collective power unleashed to light a small country. The third Truth is that the first two Truths have little to do with getting around an MX track as quickly and easily as possible. The most common Openclass problem is using the horsepower

that’s available, for the more power there is, the harder it is to use. But that’s what makes Honda’s latest CR500R different from the other ground-shakers in the Open class. With the CR, Honda is attempting to let motocross riders have their power and use it, too.

Getting the horsepower was the easy part. Last year Honda went on a power hunt and found more than enough by upsizing the CR480R engine into a 500. This year the search went on, but with a renewed emphasis on the usabilty of the power. That and other considerations lead to a multitude of changes on Honda’s Open-classer. The first and most obvious is that the CR now is liquid-cooled, as is evidenced by a diator on each side of the fuel tank.This change is hardly a surprise, as Honda’s Open-class works bikes have long been liquid-cooled, and virtually every Openclass motocrosser available in this country, aside from Yamaha’s YZ490, will be liquid-cooled in 1985.

The rationale for liquid-cooling is based both in salabilty and practicality. It’s become an accepted fact that, compared to air-cooling, liquid-cooling allows an MX bike to run cooler and produce a more consistent level of horsepower throughout a long race. But Open-classers kept their cooling fins well into the liquid age simply because they start off with so much power that a small loss seemed acceptable. Now, however, it’s been adequately proven that there are no trade-offs with liquid-cooling—it weighs no more, water pumps and radiators have proven quite reliable, and some routine forms of maintenance even are made easier, such as head retorquing and spark-plug access.

Of course, the biggest argument for liquid-cooling is based in the second Uni versal Truth: The riders want it, so the riders get it. But as significant as the move to liquid-cooling on the CR is, there are other changes of even more importance. One is the carburetion system. The CR’s 38mm Keihin carb has a flat (actually, more of an oval-shaped) slide that is made of chrome-plated zinc and is much lighter than the old-style chromedbrass slide. And as a partial response to a carburetion problem that plagued the ’84 CR500R, the carburetor venturi is extremely smooth. The slide’s bottom is smooth, and there’s no slide-stop screw—the idle speed is adjusted by turning the choke knob, which opens and closes a separate circuit.The stock jetting on the ’84 model was much too rich, but the engine would detonate when rejetted to run cleanly. And so Honda used the new carb design, along with revised specifications for the exhaust pipe, the reed valve, the porting and the combustion-chamber profile, in an all-out effort to eliminate the problem.

And that effort was entirely successful. The new CR just might be the cleanest-running Open bike Japan has ever produced. When you first start the machine it often sputters slightly until it warms up—a process lengthened as a side-effect to liquid-cooling—but after that, the CR never misses a beat. Most long-time Open-class riders have come to expect a foul-tempered, misfiring ogre of a engine from any big MX bike. After all, an engine with more than 50 horsepower on tap doesn’t need to fire on every revolution to get around the track. But the Honda runs as cleanly as any 125, only with about 30 more horsepower.

That extra power requires respect, but Honda’s goal with the 500 was to make an Open bike that has all the horsepower a rider could want and use. So the CR has an incredibly wide powerband. No matter what gear you use going into a turn, it always seems like you could have gone in a gear taller. And no matter how low the engine rpm drops, a twist of the throttle always seems to bring on a staggering rush of acceleration. The other end of the powerband is just as impressive. The motor will rev out without sputtering, running out of power or even vibrating, until you’re far past the normal operating range of most Open-classers.

Those two areas, extreme low-end and top-end power, give the new CR a big acceleration advantage over most other Open-class MXers. In roll-on drag races against last year’s CR500R, the new Honda would torque away from the old model at low rpm, stay fairly even through the midrange, and then blast even farther ahead at higher rpm. So far, no other manufacturer offers such an effective powerband.

If you’re to use that power most effectively, it’s best to keep the CR in a tall gear, upshift early and save the top-end power for the times you really need it, like turn-to-turn drag races. If you try to use the entire powerband throughout a 30-minute moto, you’ll soon find that the CR can be an unmanageable brute. It’s simply too tiring for the average non-Pro to handle all that horsepower all the time. The only disadvantage to underrevving the CR is the danger of stalling the machine. The CR has relatively little flywheel effect and so hard braking requires a ready clutch hand. Some riders will even prefer clutching the machine like a 125. It might seem frange to fan the clutch on a bike with the world’s widest power range, but that allows the rider to brake harder into a turn, and then power through the corner using the CR’s bottomless torque. Turning the CR is decisively easy by Open-class standards. This year’s CR500R has close to the same frame geometry as last year’s 500, and that means it has one of the steepest steeringhead angles in the business, at 27.5 degrees, with 4.4 inches of trail. This year, the only significant frame change is an increase in the distance from the swingarm pivot to the steering head. Honda has experimented with this dimension through the years, and claims that the change on the CR500R makes the bike feel more natural to most riders.

Whatever the cause, the CR possesses a certain kind of handling magic that is easy to live with. The quick steering makes the machine easy to flick into turns, and the power makes it easy to blast out. This year the CR500R comes equipped with a Bridgestone M23 front tire and an M22 on the rear, both of which perform extremely well on hardpacked tracks, and they add even more to the CR’s turning competence. The rear tire’s only fault is its size; despite its 5.10-18 designation, it’s small and will wear out rapidly under the CR’s power. Don’t expect to get more than a couple of races out of the stock rubber.

There are other trade-offs in the CR’s handling personality, too. On high-speed straights, the Honda has a distinct frontend shake. Correcting for this is a simple matter of sliding rearward on the seat; but in the final laps of a long moto, the last thing the average Novice or Intermediate racer wants to do is compensate for any handling quirks his machine might have. That front-end shake also can be limiting for cross-country racing.

Part of the reason for the front-end’s tendency to shake is the steep steering head angle and short trail, but even more of it is the fault of the front fork. The 43mm Showa fork is sprung rather softly, which means the front end sags, effectively making the steering head angle even steeper than it already is. The fork’s soft spring rate is even more evident in washboard-style whoops—the stadium style that are becoming ever more fashionable at local tracks. A Novice will feel the fork bottom on every whoop; a fast Pro can make the spectators feel the fork bottom on every whoop.

Even though Honda reports that the fork is the same as last year’s, no optional heavy springs were available in time for our test. That meant we had to tackle the bottoming problem by increasing the oil level in the fork, and deal with the front-end sag by adding air pressure. We eventually settled on 10-weight oil at a level of 5.5 inches from the top of each collapsed fork leg. We also put about 2 psi of air in each leg. That turned a flawed front suspension system into a good, but far from perfect, one. The fork still seemed slightly soft initially, but harsh in the final segments of travel.

Likewise, the Honda’s Pro-Link rear suspension is good, but not immune from criticism. Last year, the CR rear end was too soft for all but the lightest riders. Now, the Pro-Link system has undergone a complete reworking. The shock body is larger, and has greater oil capacity. Additionally, the Showa shock works under less leverage, and is longer so the same amount of rear-wheel travel could be retained. That also means that a lower-rate, lighter spring could be used along with decreased damping rates, so the shock doesn’t heat up and fade as quickly as last year’s.

Somewhere under all the changed spring and damping rates, though, the CR’s suspension is still lacking. Even though Honda claims the linkage provides a more linear increase in the rearwheel rate as more travel is used, the CR seems to get radically stiffer three-quarters of the way through its travel.

That’s a difficult symptom to eliminate by using only the adjustments on the shock. Less preload just allows the machine to bob up and down on rolling bumps. More rebound damping cancels most of that problem, but makes the rear end gradually pack-down in a rapid series of whoops. The answer might be to decrease high-speed compression damping, but that would require major shock surgery, for the compression-damping adjuster regulates both highand lowspeed damping. Without resorting to internal modifications, we found the best setting to be 10 clicks out on the compression-damping knob and five clicks out on the rebound. And we adjusted the spring preload so that a 165-pound rider sitting on the bike would use 95mm of rear-wheel travel.

That constituted an acceptable compromise for Novice, Intermediate and Expert riders. At this point, only the more experienced riders complained about the suspension at all. And you have to consider that Open bikes put a tremendous burden on any suspension system. The extra weight and, most of all, the extra horsepower mean that you hit every bump harder, so any flaw in suspension performance is magnified.

There’s another inherent problem with Open-classers, and big CRs in particu-

lar, though it’s not likely to cost you a race: The Honda can be downright nasty about starting. Last year the CR500R set new records for inciting colorful language on the start line, and this year the starting problem has only been partially eradicated. Honda gave the 500 a longer kickstart lever and changed the internal gearing of the kickstart mechanism so that the engine could be turned over more easily, but that wasn’t the real trouble. The shape of the kickstart lever is such that your foot collides with the footpeg at the end of each stab. And angling your foot out of the footpeg’s way just makes it easy to slip off the lever altogether and create the most interesting arc-shaped bruise on the inside of your leg. And while we’re on the improvements-that-aren’t-improvements list, we’ll tell you that the seat is wider for ’85; but instead of being more comfortable, the seat simply forces the rider into a slightly bowlegged stance.

Of course, it would be easy to nitpick any motorcycle right off the track. Besides, the Honda is an easy target when it comes to picking on little things that are wrong, because the big things are so right. Yes, the suspension needs a bit of work, but the engine doesn’t, and the engine is what an Open-classer is all about. The fact remains that last year, the CR was the best Open-class motocrosser available, and this year, it’s better. It’s a simple case of giving the people what they want. And for once, that just happens to be the same as what they can use.13

SPECIFICATIONS

$2598

HONDA

CR500R