Honda Xr600r

A LARGER ENGINE IS ONLY HALF THE STORY

CYCLE WORLD TEST

HONDA XR600R

THERE ARE SPRINT BIKES. AND then there are bikes made to go the distance. Honda's XR500R was the textbook distance bike. It was a do-it-all dirt motorcycle that was especially popular with those who measure their off-road excursions in hours or days rather than in motos or loops. Ade quate power, unfaultable reliability, good gas mileage, a comfortable seat, a strong halogen headlight and a thirst for distance all combined to

make the 500 the bike for the long off-road ride.

These long-distance dirt riders also have a saying about engine size-big ger is better. And that's why the XR500R doesn't exist any more; it's been replaced this year by the XR600R. Although Yamaha's big bore TT has been a 600 for a couple of years, and KTM and Can-Am both are using 560cc Rotax engines, Honda kept a 500cc engine in its big gest XR right up to 1985, despite having a similar 600cc engine in its XL dual-purpose bike. But Honda representatives were quick to explain that they had tried the XL600 engine as a pure off-roader and that their test riders preferred the $00.

Accordingly, then, Honda didn't just drop an XL600 engine into an XR chassis this year, even though that would have been the most logical move from a production standpoint. Apparently, Honda really did believe the XL6Ö0 engine inferior to the 500 for serious off-road use, because for one thing, the XR600R's engine has a longer stroke than either the XR500 or the XL600. The new XR's bore and stroke are 97mm by 80mm. compared with the XLóOO’s 100-by-75 measurements and the XR5Ó0's 92-by-75 dimensions. Honda claims the longer-stroke engine puts the power to the ground better than the larger-bore. shorterstroke XL600.

There are other aspects of the new XR that make it different from either one of its ancestors, too. Although the basic head layout of the XR600 is the same as the 500’s, the two intake and two exhaust valves are larger. The new intakes measure 36mm. and the exhausts are 31mm in diameter. The camshaft is the same as used in the XR500R. and second through fifth gears also are identical to those used on the 500. But the first-gear ratio is slightly taller, as is the primary drive ratio.

Despite those gearbox similarities though, the 600 shifts more smoothly than the 500, especially from neutral to first. The clank associated with first-gear engagement on the 500 is gone. Strangely enough, this improvement isn't the result of any transmission modifications, but is the end result of using new clutch plates. The 600's plates have more oil grooves that make for more precise clutch disengagement, especially during engine warm-up.

Hard-starting and off-the-mark carburetor jetting also were sources of minor complaint on past XR500s, but the 600 is worlds better in those areas. Just as before, an automatic, kickstarter-activated compression release and hand-controlled compression-release lever are standard on the XR; but while kickback was a constant problem on the XL600 and a sporadic one on the XR500. it has been eliminated altogether on the XR600R thanks to a new ignition box. That kickback, according to Honda, was caused by a weak spark. But the new XR ignition won’t fire at all unless the engine is spun fast enough to generate a healthy spark, thus eliminating the kickback. What's more, the compression subchamber—a separate chamber cast into the left side of the cylinder head—which is used to lower the compression ratio on the XL600 during kickstarting, isn't even hooked up on the XR600R. Two or three easy, but quick, kicks bring the engirte to life. And once it’s running, it shows no tendency to die before it has warmed, either. The 600 uses the same 28mm dual carbs as the XR500. but its jetting is virtually perfect.

A two-position choke lever also helps in the starting ritual. As the engine warms to operating temperature, you can move the choke lever to the halfway notch for final warmup, then flick it off when the engine starts sounding rich. Warm starts are normally a tw'o-kick affair as well.

Once the XR600R is started and on the trail, Honda's claim that it puts its power to the ground very effectively proves true. The engine starts making strong power very early in the rev range, and the healthy output continues all the w^ay up through the midrange. Thus, climbing steep, rocky hills at a snail's pace, even in second gear, is no problem. The chain-driven counterbalancer and relatively heavy flywheels (heavier than the XR500's but lighter than average for a four-stroke) smooth the thundering power strokes, and the rear tire grabs the ground without sudden, uncontrollable wheelspin.

Short-shifting is almost mandatory, though, because the final gearing—which is the same as the higherrevving XR500R's—is too low for the 600. The 600’s engine is willing to rev quite high, but once it passes through its strong midrange it produces more noise than power. We replaced the stock. 14-tooth countershaft sprocket with a 15-toother, which allows the engine to work in its powerband without so much shifting. The gearing change also boosted top speed from 83 mph to 92 mph. This might sound too high for normal playriding, but it isn't; and even lowspeed trail riding is improved with the taller gearing.

Throttle response on the 600 is excellent; there’s never any hesitation or stumble at any rpm. But although there is a substantial power increase at low engine revolutions when compared to the XR500R engine, the XR600R doesn't feel as powerful as a TT600 Yamaha or even a Husky 510TE. Long, deep sandwashes bog the engine slightly, and the 600 never overwhelms the rider with sheer torque. Drag races between the XR600Randa 1985 Yamaha TT600 confirmed the TT600 as the more powerful of the two. The TT outran the XR from a dead stop and also jumped ahead a couple of bike lengths during midrange roll-ons. The difference isn't major, but there is a difference.

But there's more to this Honda than just its new engine. In fact, listing the XR600R’s new parts would involve listing practically all its parts. The bike has a new frame with a 28degree steering-head angle (it was 25.5 degrees on the XR500R); a boxed aluminum swingarm; a new shock with a spherical bearing on each end and a larger-diameter reservoir; new fork damper rods that give less compression damping for a smoother ride across small bumps; a shorter, reshaped gas tank that sits lower on the frame; a new seat that places the rider farther forw ard on the bike; new fenders; a new airbox with a quick-release side panel for easy airfilter access; and the best OEM enduro computer ever (see “Time Tricks,” pg. 69).

To anyone who’s ridden last year’s XR500R, the 600’s new steering geometry wouldn't seem startlingly different until he got into some deep sand. Then there is a big improvement on the XR600; it doesn't knife in and tuck its front tire under like the 500 did in tight sand turns. At higher speeds in the sand, though, the stock IRC front tire doesn’t cut it. The walls of a sandwash are about the ony thing that keep the XR in the wash. But changing the front tire (we used a 3.25-21 Metzeler) can completely change the XR’s personality in sand; with a tire that works, the bike goes where it’s pointed and becomes very controllable. So take our word for it: Throw the front tire away if you intend to ride in sand.

Another area that might need attention is the suspension. While the decrease in compression damping makes the XR more comfortable on stutter-bumps, the trade-off is severe bottoming at both ends when crossing ditches or washouts at high speed. Raising the fork oil level a half-inch and increasing the shock compression damping a few clicks will decrease the severity of any suspension bottoming, but you'll lose that plush feel across the light stuff.

Still, in comfort, the Honda rates well, if only because it has the offroad world’s most comfortable seat. The seat’s width, shape and foam density all are perfect. Even long, allday rides won’t leave you with a case of the numb-buns. And the new, farther-forward seating position adds to overall rider comfort. Shifting your weight to the front tire in slippery turns is as easy as sliding forward.

This ease in rider mobility is partly due to the shorter, lower-mounted gas tank and lower-rise handlebar. Shifting your weight forward on the XR500R was a pain, for the tall gas tank stuck up at the front, the lip at the front of the seat held the rider back, and the handlebar was too high. But on the 600, the seat and handlebar are just right.

The XR600R is just right in wet, muddy conditions, too. The front fender is stronger and offers better protection, and the longer rear fender keeps rear-tire-slung mud off your back. And the XR truly is a do-anything motorcycle —even riding at night is entirely within the realm of possibility. Powerful, 155-watt lighting coils provide current to a 55-watt halogen headlight that burns bright and white, even at idle rpm.

Like past Honda XRs, the 600 proved extremely reliable. We've put 1000 miles on our test bike in less than a month and haven't had one problem. The tires were replaced at the 600-mile mark and the air filter has been cleaned three times, but that’s the extent of maintenance the bike has required.

And that’s what makes the XR a bike for the long run: staying power. Buying an XR600R with the hopes of owning a pure racebike would be a mistake; 300-pound off-road bikes don't make great sprinters. But then, there aren't many featherweights that you would want to ride over a mountain range on, or cross a desert with. So if your riding entails cross-country trips, occasional open-country enduros, long-distance reliability or just plain fun riding, the XR will do it well. And what’s perhaps more important, the XR600R will keep on doing it for a long time.

HONDA

XR600R

$2498