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Honda XR 500RE
1983 - 1984 Honda XR 500
In 1983, Honda struck a stroke of brilliance, and offered a completely 83XR 500 new XR 500. The bike's revamped engine was capped by a Radial Four Valve Cylinder head that two carburetors and two exhaust pipes connected to. The XR came with a front disc brake, frame updates, and new, beefier forks that were anything but beefy at high speed. Nontheless, people snatched the up new XR's quickly. The '83 XR 500 breathed new life into the big bore 4-stroke realm for the folks that didn't ride the European 4-strokes.
HONDA XR350R ANDXR500R
Okay, folks, time to get serious. The old XRs were nice, but far from competitive with the two-strokes. This year's 350 and 500 feature all-new engines and running gear. And they're good enough to take home the gold.
Forget everything you know about Honda XRs. The arrival of the 1983 XR350R and
XR500R marks a new beginning for Honda's middleweight and big-bore thumpers.
Although the big red bikes have long led their respective four-stroke classes,
they've traditionally worn a playbike moniker—because they simply couldn't run
beside the two-stroke enduro machines. This year's XRs cast off the old ranking.
They are so different from—and so much better than—past Honda thumpers, only
name and color connect old XRs to new.
The RFVC engines use relatively large valves; the 500's intake valve diameter measures 36mm and exhaust 31mm, while the 350's intake measures 32mm and exhaust 29mm. In comparison, the old XR500 uses 35mm intake valves and 30mm exhaust valves. The new engines employ a single overhead camshaft that spins in ball bearings and is driven by a silent-type chain, and the valve train includes some extra hardware. Since no two valve stems are parallel, the valves can't actuate through a conventional rocker system without producing heavy side loads against stems and guides. In Honda's special assembly, sub-rockers redirect the rocker arms' actuating motion into the valve stem plane. By mounting the sub-rocker arms on shafts in the rocker tower, Honda eliminated almost all increase in reciprocating mass. The RFVC engines still use screw-type valve adjusters, and a new automatic cam-chain tensioner eliminates chain maintenance.
Honda's dual-carburetor, dual-port induction system is integral to the RFVC design. Two small round-slide Keihin carburetors replace the typical single large-throat carb found on most big singles. A common throttle linkage operates both carburetors, but only the primary (left-side) carb feeds the engine at low throttle settings. After the primary carburetor opens about one-third, the secondary carb (which contains only a main jet) begins to open. A progressive linkage on the right side lets the secondary carb "catch up" so the two reach full-open simultaneously. Consequently, this system provides crisp, accurate carburetion at low engine speeds without sacrificing maximum-flow capabilities. A reed-valve-controlled passageway connecting the two intake ports passes some of the air/fuel mixture to the secondary port at small throttle openings, helping feed the engine and preventing fuel from pooling in the secondary tract as mixture "backs up" past the right-side intake valve. The 500 uses 28mm Keihins; the 350, 26mm.
Although both XR engines share the basic RFVC design, the 350 is more than just a scaled-down version of the 500. While the 350 is a wet-sump engine, the dry-sump 500 stores its engine oil in the frame backbone and front downtube. As a result, the 500 uses a dual-rotor oil pump instead of a single-rotor unit. Both bikes use a wet clutch with six friction plates, but the 350's clutch has a smaller diameter than the 500's. Also, the 350 features a six-speed gearbox; the 500, five cogs. Gear-driven counterbalancers reduce engine vibration, important considering the size of the two thumpers; with a bore and stroke of 92.0 by 75.0mm, the 500 displaces an actual 498cc, and the 350's 84.0 by 61,3mm dimensions yield a displacement of 339cc.
Honda wrapped the RFVC engines in completely new running gear. Both bikes
feature full-cradle chrome-moly frames; both the old XRs used the engine as a
stressed member. Both '83 XRs also use box-section steel swing arms; the 500's
swing arm is 0.8 inch longer than the 350's, and the 500 holds this same
0.8-inch advantage in wheelbase. Although both bikes have identical aluminum
Enlarged Showa forks replace the small 37mm units used on last year's XR500 and
XR250. The new 350 fork features 41mm tubes, while the 500 front end includes
larger 43mm tubes. Both forks incorporate dual Syntallic bushings to reduce stiction and are air adjustable; Honda recommends running the forks at zero psi.
Each fork offers 11.0 inches of travel, up an inch from last year's bikes. Both
'82 XRs used 28.0 degrees of steering rake and 4.4 inches of trail; in
comparison, the new 350 features a steep 26.0 degrees and 3.9 inches, the 500's
rake a radical 25.5 degrees and trail 4.5 inches.
The XR350, in particular, handles delightfully, thanks to a new chassis and a weight-reduction program that has pared the bike down to a modest 257.5 pounds with one gallon of gas—24 pounds lighter than the 1982 XR250, and only 12 pounds heavier than last year's Yamaha IT250J, one of the best - enduro-ready two-strokes.
The 350's light weight and precise response to rider input encourage you to throw it into corners. When you do you'll find the bike steers lightly and quickly, and the front end sticks remarkably well—especially if you keep the gas on. If you're not aggressive, sometimes the front end pushes, and it knifes a bit cornering on sandy trails no matter what. Still, the 350 is a fine, quick handler all in all.
That the 350 feels nimbler than the 500 is only partially explained by differences in wheelbase and steering geometry. What's even more significant, the 500 carries 26 pounds more than the 350—283.5 pounds with one gallon of gas. The 350's suspension works well over small and medium-sized bumps, but our heavier testers bottomed it gently over large jumps and sharp ruts; lighter riders found the suspension just fine. The 350 remains reassuringly stable over fast fireroads and along open sandy trails, and it holds its course through deep whoops—if you keep the throttle open.
At times, big whoops can overwhelm the 350 because it is down on power compared to a two-stroke middleweight or the big-bore XR. If you lose your timing, you can't rely on brute engine muscle to keep the front end skipping over the bumps. Though the XR350 offers a broad power spread and flat torque curve, it could use a few additional ponies.
Our early production 350 had clutch springs that weakened quickly; heavy use caused the clutch to heat-fade and then slip. Honda spokesmen say this problem surfaced quickly and was fixed midway through the production run; late-line bikes will have springs 0.9mm longer, and you can order them through the Honda parts catalog.
Our 350 also had a lean carburetion glitch right off idle that made the bike
hesitate and sometimes stall as the rider grabbed a handful of throttle,
especially at low rpm. Our Honda contacts tell us that replacing the #45
low-speed jet with a #48 jet relieves this problem. Unfortunately, since these
Keihins are completely new, replacement jets were unavailable and, consequently,
we couldn't evaluate the 350 with updated jetting.
For this, Honda recommends an effective procedure; if the bike resists starting after a few kicks, hold the kill button on, pull the decompression lever in, hold the throttle wide open, and stroke the starter through several times. Next, release the decompression lever and kill button, crack the throttle open a bit, and kick once more with gusto. Both the 350 and 500 kick back through the starter lever occasionally—nothing to fear if you're in good riding boots. Our 500 ran well under all engineconditions and throttle settings, and the carburetion was spot-on. This torquey big-bore pulls strongly and revs freely; though it won't dethrone any horsepower kings in the two-stroke open-class motocrosser category, it embodies all the qualities riders find desirable in big thumper engines. The 500 pulls much harder than the 350, and its five speeds are sensibly spaced to take advantage of the abundant torque. Our big thumper's shifting action and clutch performance also left nothing to be desired.
Even though the 500 steers lightly and accurately for a big bike, it feels much larger than the 350, thanks to its extra inch of seat height, its extra 0.8 inch of wheelbase and its extra weight. Despite this greater bulk, the 500 feels as if it's suspended better than the 350, easily soaking up small-to-medium-sized bumps, and bottoming less frequently over large obstacles. The 500 hooks up remarkably well, and it has enough power to get the front end light through whoops.
Most of the 500's handling shortcomings relate directly to its weight. At 283.5 pounds, the 500 is 11 pounds lighter than last year's big XR, but still too heavy for truly first-rate handling. Under most riding conditions, and especially in wide-open desert terrain, the 500 handles smoothly and predictably. When you press the XR, though, shortcomings surface. Charge through a set of deep whoops at high speed, for example, and the weight overpowers the shock, causing an incipient side-hop in the rear end. It's easy to determine the onset, and prudent riders will work within the 500's clearly delineated boundaries. The weight also affects handling in fast turns; both ends push increasingly as speeds rise. The natural tactic is to head for the berm (if there is one), and different tires may improve performance, but shedding pounds is the only sure route to optimum handling. Remember, these comments are relative to the best equipment on the market, and the important point is that the XRs are at last worthy of comparison with the best.
They have, moreover, a variety of first-class features, to enhance their appeal. Both the 350 and 500 carry a complete array of enduro-type accessories. The 3.2-gallon plastic gas tanks keep them fueled over the longest en-duro loops, speedometers and reset-table tripmeters help keep competitors on time, quick-release rear wheels speed tire changes, aluminum skid plates protect the engines' undersides, and wide plastic fenders protect the rider. A fender-mounted tool pouch contains an enduro-style multi-purpose wrench, leaving plenty of room for spare parts. As delivered, the pouches contain accessory silencing kits for the XRs that reduce noise level to 86 dB(A); with or without this kit the XR muffler systems incorporate a USFS-approved spark arrestor. While the XR350's brakes are good, the 500 features a twin-piston-caliper front disc that is outright excellent; it provides power and feel few other dirt bikes can match.
The 500 also comes stock with a superb 55-watt headlamp and a 12-volt, 150-watt
lighting system; if you want to add an accessory Baja-style running light, you
just bolt it on.
Source Cycle 1983