Suzuki Dr500

SUZUKI DR500

A Good New Engine, Updated Styling and Do-It-Yourself Front Suspension

CYCLE WORLD TEST

Suzuki's DR hasn't been one of the alltime best sellers. The original DR had an odd size 370cc engine that didn't fit into any competition size class. And the bike was further troubled by dated enduro styling. Although Suzuki had their PE line for serious competitors, many people were reluctant about buying a bike that didn't fit established classes. What if they decided to enter a family enduro or something? Still, the DR had its virtues. It was light for such a large displacement four-stroke, weighing in at 270 lb. with half a tank of gas. Even so, there was much resistance on the sales floor. Suzuki listened to the complaints and responded by introducing a 400cc four-stroke with modern styling. Unfortunately, the new model's stronger frame and better suspension components also pushed the weight up to 288 lb.

For 1981 the DR is new again. And the engine is finally a 500. Where the 400 was a bored 370, the 500 is a completely new engine. About the only thing that's the same is the bore size of 88mm. Otherwise everything is different. Stroke measures 82mm compared to 65.2 for the 400. A four valve TSCC head tops the new engine. The head shape and four valves increase fuel flow, and combustion efficiency. The valves are operated by a single overhead camshaft turned by a silent type chain.

All engine castings and internal parts are designed for the 500. The rod is stronger, the piston, flywheel weights and transmission gears are made for the larger engine, not leftover 400 pieces. The clutch is bigger to cope with the increased torque. Primary drive is via helical gear and primary kick starting is provided. The new engine also incorporates dual counterbalancers. A silent chain drives a balance shaft in front and below the crankshaft, and a second balancer below and behind the crank. Unlike the system used by Honda on the XR500 and 250, Suzuki didn't use a transmission shaft as the rear balancer. Instead the shafts are balancer shafts only.

Carburetion is handled by a 35mm push/pull Mikuni, up 2mm from the 400. Exhaust is routed to the rear of the bike by a single headpipe that goes into a sideways mounted can under the air cleaner before it reaches a spark arrester/silencer.

A compression device operated like the 400's is retained. The release lever locks down when pulled and returns to rest after the long right side kick lever is kicked. The clutch side looks like past designs, with a replaceable paper oil filter placed at the front and the clutch release lever on top. The CDI cover is now a two-piece unit that allows countershaft sprocket changes without exposing the flywheel electrics. Engine mounting is accomplished by bolting at five places including the head stay.

The mild steel frame looks the same but Suzuki says it's all-new. Large single tubes are used for the front downtube and backbone. Both split into two smaller tubes that meet at the lower rear of the engine just aft of the footpegs. Large diameter tubing is used for the seat rail and triangulation at the center of the chassis. Generous gusseting is used around the steering head and swing arm pivot.

Last year's boxed steel swing arm has been superseded by an extruded aluminum arm that looks like an RM transplant. The front of the arm pivots in needle bearings and the rear axle slot is long enough for ample wheel adjustment. The welds look sloppy but strong. The front of the arm is protected from chain damage by a nice long lasting, quiet rubber rub block. A motocross type chain guide is placed just in front of the rear sprocket. The guide is a good design that's as close as possible to the sprocket and doesn't protude any lower than necessary.

Suspension components are a combination of old and new: the forks are little changed, the shocks are new. The 38mm leading axle forks provide 9.1 in. of travel. Triple trees are aluminum, the bottom one has double pinch bolts, the upper is a single bolt clamp. Stanchion tube engagement is good, damping rates are right on, but springs are too soft. No big problem if air caps were furnished, but they're not. (Installing air caps from an RM will cure the problem, but we'll talk about that later.)

Rear suspension is handled by new KYB air/oil shocks that have bolt-on reservoirs. Right, bolt-on reservoirs! We questioned Suzuki about the reservoir style and they said they didn't know why the reservoirs bolt on instead of being cast into the main bodies. Anyway, the reservoirs are rather small. Internally the reservoirs have a piston that separates the nitrogen from the oil. Complementary cooling fins are placed at the extreme end of the small reservoirs—the end that seldom if ever has oil in it. A single progressive-rate spring is used in each shock.

Spring preload is accomplished by turning a cam ring at the top of the shock body. Five settings are available.

Hubs, wheel rims and spokes are the same as on the 400. No complaints here. The spokes are strong enough for the job, rims are aluminum and the hubs incorporate large brakes that stop the machine well.

The low-slung engine is guarded by a skid plate that's half long enough. The lower front of the engine's cases are fairly well protected but the plate ends half way back, exposing a finned sump that could easily catch on a rock and rip the bottom off the cases. While we're complaining we may as well yell about the lack of folding foot controls; off-road bikes need folding levers. Smashing the shift lever into a rock or tree can cause many dollars

worth of internal transmission damage. And trying to push a brake pedal that got folded under the footpeg from hitting something can be exciting to say the least. Folding levers make sense and modern dirt bikes should be equipped with them stock.

A new airbox is used on the 500. It uses a large foam filter that's removed from the top after the seat is taken off. Air enters through two scoops that're pointed rearward so water doesn't splash in and the top is sealed by a lid with a foam gasket.

Styling hasn't changed much on the ‘81 DR. The nice looking steel tank from last year is retained as is the seat. Plastic fenders have a rounded shape. The rear is long enough to keep most goo off the rider's back and the tail light has a rubber housing that's flexible enough to prevent breakage from vibration. The strange looking headlight/numberplate is also retained. The tool kit is housed under the numberplate and reached by raising the hinged plate. The small light is placed above the plate and has plastic guard rails over the lens but smaller rocks etc. will penetrate easily due to the wide spacing.

Controls are a combination of good and mediocre; the hand levers are dog-leg shaped (something still missing on Suzuki's RMs), the double cable throttle isn't a side pull, the footpegs have aggressive claw tops and strong return springs, the rear brake pedal has a saw-toothed top but doesn't fold, the shift lever doesn't fold, a small resettable odometer has large easily read numbers and all of the control cables are quality items that're routed through good guides.

The DR is easy to kick over . . . considering it's a 500cc four-stroke. The long kick lever and compression release ease starting considerably. Pushing the easily reached choke lever and kicking briskly with no throttle gets a cold engine purring in one or two kicks. A warm engine usually fires in one or two kicks also. The key word in the last sentence was usually. Like all large four-stroke Singles, the DR is sometimes hesitant when warm. This usually happens after the engine has been off for four or five minutes. Then it's possible to wear yourself and two or three of your buddies out starting the damn thing.

The 500 engine makes pleasant power. No great rushes of bhp to cause wheelspin, no jumps or peakiness, no notchiness or hesitation.

But frankly we had trouble telling

much difference between the 500 and last year's 400. Both engines have an abundance of smooth pulling power. Unfortunately we didn't have a 400 around for a direct comparison, but none of us felt there was a dramatic difference between the two. The power is smooth and everyplace, the gear ratios are perfectly matched to engine performance, the clutch lever pulls easily and the clutch doesn't slip, the exhaust is quiet and the transmission shifts positively.

We would like to tell you the big DR handles well or even fairly well . . . but stock, it doesn't. The bike wallows around, pitches and twitches, bucks and dives. The main problem is fork springs that're way too soft. The shocks are about right for the 296 lb. bike but the combination of soft front and semi-stiff rear make the bike's balance completely off. Riding the DR500 fast in stock condition is scary. Staying upright takes 100 percent concentration and constant correction. Forget about watching the scenery, you don't have time. Keeping the bike in the trail and under you, not the opposite, demands all your attention. With the suspension out of balance the bike puts the power to the ground poorly. Climbing rocky hills, especially shale type rock hills, is almost impossible. The rear wheel spins and not much forward motion takes place. We had a Yamaha IT465 along for a control the first outing. The IT465 did everything much better than the DR500. Hills that the DR could only climb halfway were topped in second or third on the IT. So much for the fourstrokes-climb-hills-better theory. The DR doesn't run out of horsepower or torque, the rear wheel just spins and refuses to bite. You can't get over the top if the rear tire doesn't get traction. The problem isn't the tire brand or knobby design or tire quality. The overly soft forks are the major culprit. The springs are so soft the front end of the bike darts around, twitches and hunts, and most of the travel is used up by sack. The constant correction required while riding the DR, combined with the wallow and low front end all work against the rider. Also, not enough weight is transfered to the rear wheel with the front riding so low. The springs are probably about the right spring rate for a 125 motocrosser. As delivered, the DR has problems.

We decided to try and fix it. Two solutions popped into our heads; install heavier fork springs, (if we could find some), or go the easy route and replace the fork caps with ones incorporating air valves. We tried to find air caps without success and ended up drilling and tapping the stock caps. Valves from an auto parts store screwed right in. Total cost, since we already had a Vs pipe tap, was less than $2.

After several hours of trial and error with different weights and volumes of oil and different air pressures we hit a good combination: 9oz. of KalGard #20 oil worked well: and 14 psi air turned the DR500 into a great play bike. Suspension front and rear is well balanced, the rear wheel gets good traction on hills (it still won't outclimb an IT465 though) and generally, the bike is fun to ride. Fast bumpy trails can be blasted down with confidence and good rider control. The DR still doesn't handle rough ground as well as Honda's XR500. It'll go over gnarly ground just as fast (with the forks modified), but rider comfort isn't nearly as good.

With the suspension working properly the engine seems more tractable and more powerful. Engine output is adequate for the designed use of trailing and general play use. Most other pieces and parts on the DR500 work well: Both brakes are strong and progressive; the clutch pulls easy and doesn't drag when in; the bars are shaped right and are the right height.

We did a little night riding on the DR and found, to our surprise, the headlight isn't half bad. A fairly rapid pace can be maintained because the light throws a> good beam. Only one filament is furnished, no high and low, and the light housing could use a small extension at the top to keep light from distracting the rider. We used a couple of layers of duct tape across the top of the plastic lens guards and cured the complaints about light-in-theeyes when riding over the bars.

SUZUKI DR500

$1999

The obvious question is, does the DR500 with dual shocks work as well as Honda's single shock Pro-Link? The answer is yes and no . .. The engine works better, the suspension doesn't work as well. The Suzuki 500 engine is smoother, easier to start (most of the time), produces more power and gets better gas mileage. The DR will go through bumps as fast as a 500 Pro-Link (after air caps are added) but it won't go through them as smoothly. The DR will stay straight and true and it'll stop as well, and it's about the same weight, about the same price and has the same parts availability. If you're looking for a new 500cc four-stroke Single, drop by a Suzuki dealer and give the DR500 a good long look.