Honda XR 600R

1985 - 1987 Honda XR 600

Honda, realizing that more cc's meant more power, injected a 100cc 85 XR 500   dose to the XR 500 engine making the XR 500 an XR 600 in 1985. This made a fairly strong running machine run a bit stronger. Other changes included an aluminum, rather than steel swingarm, a dry sump engine oiling system, and frame changes.

Except for graphics, the XR 600 did not change appreciably until 1988.

 Cycle World 1985

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 offroad excursions in hours or days rather than in motos or loops. Adequate power, unfaultable reliability, good gas mileage, a comfortable seal, 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 riders also have a saying about engine size-bigger is belter. And that's why the XR500R doesn't exist any more: it's been replaced this vear 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 biggest 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 500.

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 XL600 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 XL600's 100-by-75 measurements and the XR500's 92-by-75 dimensions. Honda claims the longer-stroke engine puts the power to the ground better than the larger-bore, shorter-stroke 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 jelling also were sources of minor complaints on past XR500s, but the 600 is worlds better in those areas. Just as before, an automatic, kickstarter-activaled 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 engine 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 two-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 way 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 higher-revving 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 low-speed 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 28-degree 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 forward on the bike: new fenders, a new airbox with a quick-release side panel for easy air-filter access, and the best OEM en-duro computer ever.

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 light 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 only 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.

Still, in comfort, the Honda rates well, if only because it has the off road world's most comfortable seat. The seat's width, shape and foam density all are perfect. Even long, all-day 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-any-thing 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 en-duros, 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.

TIME TRICKS

Thumpers have always made ideal playbikes, but now Honda wants them to be known as competitive enduro mounts as well. To that end, the 1985 XR350R and XR600R have been titled with the most impressive digital-readout enduro clock ever put on a dirt bike as original equipment.

This isn't the first time a digital clock odometer has made a dirt-bike appearance: Kawasaki tried it first on the KDX models. But those first Kawasaki units were beset with problems, not the least of which were hard-to-read numbers, and a clock and odometer that couldn't be simultaneously displaced on the screen.

Kawasaki learned from those mistakes, and its '85-model KDX200 has an improved clock. And it seems that Honda also learned from Kawasaki's mistakes. The clock on the XR600R and XR350R has large numerals that are easy to read, even in bright sunlight. The instrument's right side features a built-in countdown clock that starts with a push ol the right-hand button. The left side contains the display for the odometer, which reads in miles, tenths, and even in hundredths.

Resets are made easy with the two left-side buttons: The far left button advances retards the readout in full miles, the second button advances retards in tenths of a mile Pushing the right-hand button (after the clock starts) changes the odometer display to miles per hour, just in case the rider wants a speedometer.  The button second from the right is intended to be pushed at the three-mile speedometer check that all enduros include: and if there is a mileage difference between the XR's reading and the designated three-mile point, the odometer will automatically compensate for it, eliminating the need for the rider to make mileage recalculations during the event.

This calibration put Honda's combination enduro clock/odometer/speedometer: another step in the XR's evolution from playbike to racebike. This also makes things easier if you've changed to a front tire with a different diameter: pushing the button at the three-mile point recalibrates the clock to compensate for the new tire's diameter. That recalibration remains in effect until the unit is shut off.

The odometer is driven by a normal speedo cable from the wheel to a junction box under the numberplate; two wires run from the box to the odometer/clock. Three AA batteries supply electrical power.  An on off switch is recessed into the left side of the unit. To eliminate battery drain, the clock turns itself off after receiving no input for two hours.

Simply put, Honda's digital odometer/clock unit is the greatest OEM enduro instrument ever offered on an off-road bike. It makes standard-issue clocks and odometers seem prehistoric by comparison. Luckily, for those riders who want the latest in timekeeping gear, adapting this unit to other enduro bikes shouldn't be much of a problem. Except for the cost, that is: Buying all of the individual components will set you back a cool $250. — Ron Criew