Honda Xr500r

HONDA XR500R

CYCLE WORLD TEST

It was always a great play bike. Now it's a great race bike.

Competition proven. Race-bred. Ride a winner. Sure, we’ve all seen the ads, but when it comes down to the fine print, the winning bike and the production bike usually share name, paint and a few parts.

Not this time. Honda’s new XR500R (which shares nothing with the original XR500R except the name) really is nearly identical to the off-road racers and it really is a winner.

By design, you might say. Honda gave Jack Johnson and AÍ Baker an XR500 prototype, which they prepped and then rode to victory in the Baja 1000, beating the second place bike by an hour. Then Bruce Ogilvie and Chuck Miller took an-

other XR500, changed the exhaust and the air filter and won the Parker 400. And then Ogilvie took his XR500 to a 100-mi. grand prix at Riverside Raceway and won that, too. Amazing.

Now the XR500R is in production and it incorporates both the factory’s ideas tested by the racers and the racers’ suggestions given back to the factory.

This XR500 is a different bike from the old model. The 1983 model shares no parts with the original. Like the XR350 (with which it also doesn’t share parts) and the XL600 (which does have parts in common) the XR500 is a member of a new family, the third generation of Honda Singles. This is a dry-sump four-

stroke, which makes the engine more compact and helps cool the oil. Compared with the old XR500, the engine is 2 in. shorter, an inch narrower and an inch smaller from front to back. It also weighs 6 lb. more, due to a stronger fivespeed transmission. Weight is 95 lb. with carburetors attached.

At the top of this engine is the radial four valve head. Previous Hondas with four valves had a pair of intake valves inclined together, and a pair of exhaust valves inclined together, a good way to get maximum valve area in a cylinder head.

Now, there’s a better way. Imagine a ball, about the size of a bowling ball. Lop off one side of the ball, about a half-inch slice. The cut-off slice is the shape of the Honda’s combustion chamber. And the four valves are splayed out in four different directions, as though they were pointing to the center of that bowling ball. This gives more valve area above the piston, for better breathing, and it also might increase the turbulence of the incoming mixture, for better power at lower engine speeds.

To push these four valves extending in four different directions, the XR500R has one long camshaft and a combination of eight cam follower levers. Normal rocker arms couldn’t push directly on the valve stems, so the primary rocker arms

push on smaller finger-type followers, pivoted so these secondary followers can push directly on the ends of the valves. A spark plug fits exactly in the middle of the head, so it has the shortest possible distance for the flame to travel. This means higher compression can be used, and this year’s XR500 has a 9.2:1 compression ratio replacing the 8.6:1.

Bore and stroke is more oversquare, 92mm x 75mm. The old XR had figures of 89mm x 80mm. The larger bore makes room for bigger valves and the shorter stroke keeps piston speeds lower, so the engine can rev higher. The piston is flat topped,with small crescent-shaped cutouts for the valves. A single counter-

balancer shaft in front of the crankshaft is driven by straight-cut gear. A linkplate cam chain is held by an automatic cam chain tensioner. Another straightcut gear drives the larger clutch, which still uses only four compression springs. The primary drive ratio has been revised, but the transmission ratios are the same as they were on the old XR500.

As on the smaller XR350, the 500 has two-stage carburetion. Each intake valve has its own intake port and its own carburetor venturi. Only the left carb has an idle circuit or choke, because it’s the only carb open below one-third throttle. When the throttle is twisted more than one-third open, the righthand carb begins opening. Between the two intake ports is a small steel reed valve providing a slight amount of air flow at low engine loads. Having the mixture enter the cylinder through only one intake valve at low speed improves turbulence and having a smaller carburetor for idle and lowspeed work makes the engine run well at part throttle.

Separate exhaust ports are spaced farther apart, with an open passage between the ports improving cooling around the exhaust valves.

Allen-head screws are used on all the sidecovers, except for the oil filter cover on the righthand side of the engine. Another oil filter is in the bottom of the frame downtube, which doubles as the oil reservoir. Another filter is a wire screen in the bottom of the engine cases. Oil capacity is 2.6 qt. when the downtube, backbone and oil lines are all full. The compression release operates automatically when the primary kick starter is moved, or when a small lever on the left handlebar is pulled.

The chrome-moly frame is as impressive as the new engine. It’s a full cradle design, large tubes wrapping completely around the engine. Because the backbone tube and downtube are used for oil storage, they’re especially large. At the bottom of the downtube, two smaller tubes wrap under the engine and join the rear downtubes. All joints are well gusseted and good triangulation is used in the mid-section. The tubes holding the

seat extend back to form a rear fender mounting. Just where you want a grab handle, the fender wraps around the frame tubes, making a great place to pick up the back of the bike.

At the front of this frame is an extremely steep 25.5° steering head. Short triple clamp offset produces a more normal 4.5 in. of trail. At the back of the backbone tube is the top mount for the single rear shock. Around both sides of this shock are air ducts connecting the two carburetors with the excellent airbox. A dual-stage foam filter is held in place by a quick-release wire bracket. The side numberplate functions as the airbox cover, and is held on with screws.

Nothing has been forgotten on the ’83 XR500, not even the suspension. Travel is 11 in. at both ends. Giant 43mm forks are held in double pinch bolt triple clamps and protected by good accordion boots. Air caps are the only sources of external adjustment.

An aluminum-bodied Showa shock is used with the Pro-Link rear suspension. Forged aluminum suspension links connect the rear shock to the steel swing arm. Grease fittings are placed at the lever joints and on the swing arm pivot. An aluminum reservoir for the shock is mounted on the left side of the frame. A knob on the reservoir adjusts compression damping to any of 20 positions, though the standard position in the center works well and little adjustment was needed during testing. Rebound adjust-

ment requires working a small disc on the bottom of the shock. A small screwdriver can reach it, but our bike didn’t need adjustment. Spring preload is more difficult to set; the screw-adjust collars are on the top of the shock and require use of a long punch after the sidecovers are pulled. Small adjustments have a large effect on the Honda.

A quick-detach rear wheel fits on back of the swing arm. The axle slot is extended to the back of the swing arm, with a lower edge extending behind the slot to hold the axle for easy removal. A slot holds the backing plate and the brake rod has a spring-loaded quick release. This isn’t as easily removed as the wheel on a Suzuki PE, but it’s still very easy to loosen the axle nut, slip off the chain and brake rod and pull the entire wheel assembly off the swing arm. Straight-pull spokes connect the small hub to the aluminum rim. A double row of serrations on the inside of the bead keeps the rear tire from squirming.

A large hydraulic front disc is used, and it’s super. An adjustable master cylinder connects by braided steel line to the double piston Honda caliper. The lightweight disc is drilled for even less weight. Straight pull spokes are also used in front. Six-ply IRC tires are mounted front and rear.

Plastic parts on the XR show a lot of thought. The front fender extends far enough forward to keep mud off, and the rear is just as useful. Both are wide and well made. The 3.2 gal. plastic tank is good for 100 mi. between fillups and is as short as possible. The seat is built on a plastic base, has excellent foam and the cover is molded to fit the foam without any seams visible. The forward part of the seat extends over the back of the gas tank, but it’s too steep a rise to allow sliding on the tank. At least it can keep your voice from changing.

Finally the XR uses a normal handlebar bend. The shape is like that on the CR motocrossers. The grips are soft, strong and long-lived. A tiny push-pull throttle works smoothly, but the carbs have too-strong return springs, requiring more effort than ideal. Levers are Honda’s pull-back ball ends, and they clamp on the handlebars with split clamps, so grips don’t have to be removed to change levers.

All the proper enduro accessories are standard. An excellent tool pouch on the back fender holds a spark plug wrench, screwdrivers and a six-day multiwrench. The odometer has large numbers and there’s also a 90 mph speedometer. Besides the forest service approved spark arrester, there’s an additional silencer core in the tool kit for even quieter operation. The aluminum skid plate is a work of art. The lower bolts are recessed, it has lots of holes for less weight and less mud scooped up, plus the holes are positioned so engine bolts can be tightened with the plate in place.

Little things usually aren’t noticed when you buy. a bike, but become important when you live with it. The XR has lots of those little details. O-ring seals are fitted on the brake pedal pivot to keep dirt out. All the cables are first class. A leak-proof joint is used where the headpipe connects to the silencer pipe. Both carbs have water drains and the idle speed screw is large enough to be adjusted without tools.

To keep the bike as light as possible, and still affordable, the bolts have deepdish heads, while the swing arm pivot bolt and the rear axle are hollow. Hollow pins are used on the footpegs, with a cotter pin holding the pins in place. Even the steering stem is aluminum. Most of the frame gussets have holes stamped into them. About the only places where weight could still be saved are the silencer and swing arm. Even these are lighter than they look. The silencer weighs 6.5 lb. and the swing arm is only 2 lb. heavier than an aluminum arm.

The XR500 is an easy-fitting bike. The 36.8 in. seat height is reasonable, considering the suspension travel. Bars, pegs, and all the controls feel right, and the seat is great. Starting is easy, due to the automatic compression release. Pull the choke on the left carb, poke the kickstarter a couple of times and it’s running. It starts easiest without any special technique. Just kick it hard. Full choke and no throttle works best cold, though the petcock occasionally pushes the choke back off when the bike is cold. After that, the engine is a dream come true. The counterbalancer effectively reduces vibration to little-bike levels, while the 5.5 lb. CDI flywheel helps the Honda chug along at idle. The dual-stage carburetion works perfectly, not spitting back or stalling the engine. The Honda can chug along all day without fouling plugs, overheating or complaining. Give the bike a little more throttle and it responds strongly and quickly. There are no flat spots in this wide, wide midrange. Open the throttle all the way and there’s more power still.

At first the XR500’s power is deceiving. Things don’t happen immediately, but they happen smoothly. The front end feels heavy, requiring some adaptation before the rider can pull the front wheel up at low speeds. The heavy flywheel and added weight of the counterbalancer keep the rear tire from spinning wildly. This controllable power feels better after a rider adapts to it. Honda says the XR500 has 41 bhp, 10 horsepower more than the XR350. At first it doesn’t feel like it has that power, but the longer a person rides it, the faster he goes and the more powerful the bike feels.

Ridden well, the XR500 has power that’s competitive with other big bikes, right from the crate. Big full-lock slides through deep sand washes are no problem. Just pitch the bike into a big sweeper and turn the throttle to the stop. The XR backs in like a good TT bike. Fire roads are pure fun on this bike.

HONDA

XR500R

$2298

Shifting the XR took more work than usual until 500 mi. were run up. Even then, it takes more concentration to avoid missed shifts. The lever has to be pulled all the way up or it pops back out of gear. Gear ratios are ideally suited to the engine, with low fine for crawling over rocks and fifth good for a little over 80 mph on the speedometer.

Just as the power requires practice to use, so does the chassis. Whoops are the Honda’s specialty. It’s amazing how fast the Honda can be ridden through deep, killer whoops. No 288-lb. bike is going to skip across the tops of whoops, but the Honda can plow through unperturbed, faster than anyone has a right to expect of it.

A little front end tuning helped response over small bumps. With the oil level at the stock 5.5 in. level the forks are a little harsh. At really high speeds impacts run right to the rider’s arms and shoulders. Lowering the fork oil level 1.75 in. lets the forks react better to small, sharp bumps, while not bottoming on the large dips.

That 25.5° steering head angle helps the XR turn like no XR500 before. The strong frame, big forks and strong swing arm gives it a crisp feel in corners, with nothing flexing or feeling disconnected from the rider. The expected head shake just doesn’t happen, either.

When it comes time to slow down, the XR has the best brake going. The big disc is powerful and progressive. There isn’t a surprise in it. Even repeated deep water crossings don’t phase it. That tiny rear brake that looks too small works well, combined with the engine braking, and never grabs or stalls the engine.

As it comes from the factory, the biggest flaw on the bike is the junk front tire. It skates and is terrible in sand. It just digs in and cuts through, no matter where the forks are set in the triple clamps. With the stock front tire filed in the trash bin and a 3.25-21 Metzeler installed, the skating disappeared. For most of our riding in open areas, pushing the forks down in the triple clamps to the top ring worked best. For woods riding it would be better at the second ring.

In a month of normal testing the XR somehow accumulated over 1200 mi. It just worked so well over such a broad variety of conditions that it was in continual use. We love it.

Compared with one-off custom fourstrokes or the older XR500s the new XR is superior in every way. It has competitive power, handles great and can go 100 mi. with the throttle wide open. That’s how it’s been ridden and it hasn’t broken a thing. We’ve worn out two of the excellent six-ply IRC rear tires and the stock O-ring chain and sprockets, but the rest of the bike is still running like new. Even the small spokes are holding up, only having needed a minor tightening once.

So here it is. The best custom openclass four-stroke racing bike made. And it’s already put together, with nothing needed but a new front tire.