SUZUKI RG500 GAMMA
(Undoubtedly the most exotic motorcycle to ever hit the street!)

Gamma Forum For Sale Shop Manual Service Info RG Specs 400/500 Differences RG Gallery RG GP History RG500 Reviews RG Mailing List Transmissions RG Miscellaneous Randy's Addiction Erik's RG Site Suzuki-rg500.com Gammagir1 Rob Koopman RG500.com French RG Site Yellow Dog Cycle 85 S. Stephens Tuning Online Shops Jim Lomas Exhaust Lance Gamma Nikon Exhausts Airtech Fibreglass Carron Exhaust Dennis Kirk Tires Unlimited CycleSuperStore Dynojet LockhartPhillips otorcycle Links Lane Splitting 101 RG Pics Magazines Motorcycle.com MCN RoadRacingWorld ESportBike Cycle World Motorworld Cycle News Roadracing News RG500 Specs: 498cc 2 Stroke Sq. Four 406 lbs Wet 4.5/1.3 Gal Tank 279/72 Kms Range 6 Speed Tranny Rotary Valves 28mm Flat Mikunis 7.0-1 Compression 96 Horsepower 110/90 16 F Tire 120/90 17 R Tire 56.1"  Wheelbase 25.2 Degree Rake 31.3" Seat Height 5.8" Clearance 0-60 in 3.04 sec 1/4 M in 11.37 sec Braking 60-0 111ft     My Home Page Email Gammagir1 My Bikes

"You see judge, this motorcycle is, well, enchanted. Sounds crazy, but this Gamma is an ETM, Extra Terrestrial Machina, an alien blue and white ray, darting, ricocheting and beaming from place to place in the Slumbering land of Fifty-Five. Sir, one really has to wonder whether a rider uses the 500 Gamma to open difficult roads with surgical precision----or whether the Gamma mysteriously and magically uses the rider as a witless tool to play its own amusing road games. What's that your honor? I've been reading too many Stephen King thrillers where runaway lawnmowers massacre unsuspecting suburbanites? Irresistible. The Gamma is irresistible! Standard equipment should include the Riders Rites for Absolution for acts soon to follow. The rider herein cannot be held responsible for acts committed as an accessory to the Gamma! Raw numbers first indicate the Gamma's spellbinding qualities. With its reservoirs for gas, oil, coolant and adrenaline all topped off, the RG weighs 406 pounds. Given its 95 rear wheel horsepower from 30.5 cubic inches, the 500cc Gamma has a horsepower-to-weight ratio in league with the strongest one-litre Superbikes of not only its day, but the Superbikes of today! Clean up the Gamma's jetting, and would likely be into and through V-Max territory quicker than you can say "still too rich". Lightness sharpens the edge of the Gamma's horsepower. V-Max power is a bludgeon with a velvet cover that wallops you forward with unending force. Gamma power is different; it has the quality of an arrow shot from God's own crossbow--instant and direct. By no accident did two stroke four cylinder 500's come to dominate Grand Prix racing. For supersport street machinery, the 86 RG500 Gamma and the 86 GSX-R 750 are nearly comparable low-mass machines. According to factory figures, the 750 makes about 10 more horsepower than the RG500, but the GSX-R weighs significantly more than the Gamma--some 50 pounds. The four stroke needs about an extra 250 cubic centimeters and thus an additional 10 horsepower to match the power to weight ratio of the two stroke Gamma. Obviously, a 500 cc or even a 600 cc four stroke can't touch the Gamma. The GPz Ninja makes about 10 horsepower less and carries an additional 70 pounds. Run the RG past 7000 RMP and the space ahead collapses around your helmet; here does something more than become there; here is there! Everything the Gamma does, it does quickly. The Gamma's geometry tucks the front end back more severely than any production street motorcycle in our collective experience. The head angle is 25 degrees, 10 minutes, tail a steadying 4.4 inches. the squat front end rolls on a 16-inch wheel, and the wheelbase measures 56 inches. So faithful is the Gamma to the rider's body language that, should he roll his eyes upward, he thinks the RG would lift off and fly. Maybe the only thing the Gamma doesn't do is respond directly to brain waves. Good ideas can stick well anywhere--street or track. the square four compromises two parallel twins, once behind the other. The rear set rises about a half-story higher than the front set, and the entire engine case and cylinders mesh with a common drive gear on the interior end of jackshaft that, in turn, gears to the clutch on the right side of the engine. The transmission, a racing style side-loading unit, is located partially below and behind the engine. Rotary valve induction requires outboard carburetors but is generally a good thing for high power output. Water cooling makes possible a compact square four, enabling the cylinders to group tightly together, with the rear cylinder exhausts running straight back. The result is an incredibly dense engine, with much of its weight slung low; the unit can push far forward, locating the mass very close behind the front wheel. As a rule, four stroke engines don't readily lend themselves to compactness the way square four two strokes do. Four stroke Vee's are narrow, but long and/or high; four stroke inlines can have high heavy cylinder heads, and lay down inlines must fight length. Park the Gamma after that first brief ride--which is nothing less than an invitation to criminal activity--and you'll marvel at how close conceptually this street-going Suzuki is to a real RG racer. RG hallmarks abound: an aluminum alloy (aluminum, magnesium, zinc) frame and a two-stroke, square four engine, with upstairs/downstairs banks and basement gearbox, rotary-valve induction and power-valve-and-chamber exhausts. The street Gamma shares almost every conceivable piece of sports-spec hardware with a half-dozen or so supreme road-blasters inside and outside the Suzuki range. Still, the Gamma is a racer-replica in concept only; to understand that all you need to do is look at a pure racing RG500, which sized like a 250, makes 10-130 horsepower, and has a power-to-weight ratio of about two to one. Suzuki engineering has exploited the two stroke's advantages in the Gamma, bringing street reality into synch with the theory. Other high performance two stroke roadsters are light but not necessarily feathery: Yamaha's four cylinder RZ500 weighs almost 500 pounds. the RZ350, loaded with catalytic mufflers weighs 381 pounds. Honda's impressive little three cylinder NS400R weighs 415.5 pounds. Since none of these kick start two strokes have to haul around electric starters or big batteries they all can nick off even more weight compared to the four stroke competition. But even in the two stroke world, the Gamma is a featherweight, and that advantage must have come out the old fashioned way---the hard won diet. It's tempting to explain the Gamma's lightness as a function of the aluminum alloy frame. What a piece of work! The entire steering head is a pressure casting, as are the rear section members supporting the swing arm pivots. The use of strong, lightweight pressure castings both pleased the calorie counters and simplified, we imagine the production of the frames, by eliminating a lot of hand fabrication. (Robots weld the current frames together). The massive steering head doubles as the cavity for the air cleaner box, and this use of multi-duty parts is characteristic of the RG500 Gamma. One intricate piece serves where two might have been fitted. Suzuki engineers point out that this frame is really a triumph of computer work. Extensive modeling and analysis produced the shapes and pared weight. Consider the frame members supporting the swing arm pivot pin. The interior walls have extensive, delicate webbing. Consider, too, the basic box-section frame members. In cross-sectional view, the boxes have ribbed corners, in order to increase the strength of the member. Or, seen differently, the exterior walls of the box members, away from the corners, have been removes slightly. The alloy swing arm, showing the same ribbed-box construction, connects the Gamma frame in a Full Floater system similar to the GS700/750 series motorcycles. This system attaches the bottom eye of the shock to a lower bridge on the swing arm and connects the shock's top eye to the leading arm of the bellcrank. The bellcrank's trailing arm communicates with the swing arm via a link, and the bellcrank pivots on a pin anchored to the main frame. The linkage system is gorgeously sculpted----links, rocker arm, lower shock mount. Poke your head under the Gamma and peer upward in front of the rear wheel. Your wondering eyes will see the underside of the swing arm cross brace, the top of which locates the connecting link to the bellcrank. Even the underside of this pressure cast cross brace is a thing to behold. It is an intricate universe of webbing, and a lot of empty space. Space weighs nothing. Or at least not much! Tempting though it may be, it's too simplistic to explain the Gamma's leanness totally in terms of its frame. Suzuki weight watchers have been everywhere. Pop off the riders section of the saddle: 1.9 pounds. Our Canadian spec bike weighs exactly one pound more than the Japanese domestic model. The difference, we think, lies solely with the dog eared turn signals on the Canadian version. Suzuki engineers may have sweated as much over the RG500's power characteristics as the running gear's weight. High performance two stroke engines traditionally have relatively narrow powerbands with exciting, high rise curves. Disc valve induction, which produces intake timing independent of piston positioning, has been one method of broadening power output at even higher redlines. In GP racing, Suzuki stuck with rotary valve induction. After a point, Honda and Yamaha engineers felt peak output was less important than manageable soft power in the so-called powerband and turned to reed-valve induction for their GP500 bikes. In the street Gamma, as well as in the last series RG racers, Suzuki engineers spread power with an exhaust valve arrangement. In Suzuki's Automatic Exhaust Control System, an electronic servo motor and cable system barrel valves, located in the roofs of the exhaust ports, according to engine speed. These barrel valves, which have large passageways through their centers at right angles to their rotational axes, open up into small ante-chambers cast into the cylinders above the ports, effectively increasing the head pipe volume, in a way reminiscent of Honda's ATAC system with its butterfly valve and sub-chamber. Turned on a 6 and 12 line, the valves and their passageways are open doors to the ante-chambers. Rotated to a position on the 9 to 3 lines, the valves seal off the roof of the exhaust port. The barrel exhaust valve itself may resemble the Yamaha system in appearance, but functionally the Suzuki valve, far away from the port window, does not operate like a window shade varying the effective exhaust port height. And in the Suzuki system, the barrel turns quickly to an open or shut position. Yamaha's barrel valve lifts gradually, over a period of a few thousand revs. All these exhaust valve systems, however, have the same effect: they boost midrange engine power. Varying the exhaust volume allows the arrival of the pressure wave coming back to the exhaust port window from the far end of the pipe to be spread out over a controlled schedule. That's important because this pressure wave actually stuffs the leading front of the fresh charge, coming in through the transfers and flowing out the exhaust port, back into the cylinder. In this system, akin to stuffing a sausage from both ends, that allows two strokes to make impressive power. For good bottom-to-mid-range power, the trick is to fool the exhaust ports open late, and then, with increasing speed, allow it to believe the port is opening much earlier (or higher) for strong top-side punch. More tools that spread power in the RG are the relatively small and short 28mm flat-side Mikuni carburetors and the "Suzuki Intake Power Chamber," a fancy name for a tube running between adjacent sets of carburetors. The interconnector terminates above and behind the flat sides in the carb bodies, and there the carbs have small built-in venturis. This open channel lying behind the sides and in front of the rotary valves allows one cylinder drawing charge from its own carb to also feed from the carb of its companion cylinder at high engine speeds. At low and medium engine speeds the "small" 8mm carbs are necessarily for relatively clean and crisp carburetion, because big-bore carbs, say 36mm, wouldn't atomize fuel properly. At high engine speeds though, a single 28mm carburetor lacks the size to meet the demands of its cylinder and here the interconnector aids the struggling carb. In the Gamma, cylinders on the same side run 180 degrees apart. When the rear cylinder is taking in charge (a vacuum in its inlet track), the front cylinder's tract affords a high pressure area (rotary valve is shut). The carb slides to both cylinders are open, but in the front cylinder the charge stacks up behind the closed valve. With the manifold connector, this fresh charge is pulled into the rear carb, where it's discharged into the inlet stream. The rear cylinder gets an extra charge of mixture, just as if the rear carb were suddenly larger. Despite the engineering department's skillful and resourceful massaging, the Gamma's output curve still resembles a spike. Imagine a motorcycle that whistles along at 6500 rpm making 37.5 horsepower, and then in a single shriek doubles its output and more, reaching almost 70 horsepower at 9000 rpm. That's 37 horsepower concentrated in a single snap across 2500 rpm. In our recent experience the only other normally aspirated motorcycle that more than doubles its power across a 2500 rpm field is Yamaha's V-Max, which explodes from 41.7 to 88.6 horsepower running through 3500 to 6000 rpm. Even so, the Gamma's snap quality belongs in a higher realm. A 406 pound motorcycle is genuinely light, and with a 150 pound rider aboard, the Gamma actually jumps harder under full throttle, 6500 rpm to 9000 rpm, than does the V-Max across the steepest 2500 rpm incline in its power curve. Power to weight figures support that gut feel. For a street bike, the Gamma's power spike quickness is for most riders about a dozen heartbeats beyond full terror. Strangely, the Gamma attracts two kinds of motorcyclists. First, those who love the RG500 for what they think it is, but who cannot ride the bike well enough to be sure. Second, a tiny minority of truly expert riders who understand how incredibly good the RG can be, and who also know what patient, studied setup it demands. Anyone who hops on a Gamma fresh out of the crate and proclaims the bike an easy machine to ride quickly has fooled himself and betrayed his wet ears to his expert friends. Honda VF500 Interceptors and Kawasaki Ninja 900's may encourage skirting the limits after a brief acquaintance--but the Gamma is another story. A different, more complex motorcycle, the RG Suzuki is much like a race bike. Extraordinarily sensitive, in need of expert tailoring to individual riders, and potentially lethal in the hands of fools. And like a road racing motorcycle, the Gamma's limits at first lie far out in murky territory. You must approach those limits carefully and deliberately, because the RG draws the boundary line between safety and road rash far narrower than other sport bikes. What's more, an engine with a light switch power makes that thin line brittle as well. That's just for starters. Item: Tire selection. Our Gamma came shod with a Michelin A48 110/90-16 in front, and a M48 120/90 17 at the rear, relatively tall, high tires that aren't by current sporting standards particularly sticky. The stock tires do, however, give the Gamma necessary ground clearance. With them you nick the sidestand pad on the left and graze the fairing on the right. Furthermore, the M48 profile keeps a big rubber patch on the ground when the bike is leaned over and accelerating. Think of the A48/M48 combination as a warning to the initiated: stickiness isn't everything! Try a soft, tall rear with a wraparound tread and you'll find its narrow contact patch undesirable because the Gamma's steep power curve spins the tire off corners with the bike still banked over. It's likely Suzuki purposely avoided low profile, super sticky tires like Michelins Hi-Sports. Familiar with such tires, a rider might be encouraged to fling the Gamma into the first available set of corners, use up ground clearance, dig the pipes into the pavement and find himself in a heap of trouble in no time flat. Item: The Powerband. Riding the Gamma on tight twisting canyon roads is no treat. Expert riders won't find enough horsepower below 7000 rpm to entertain themselves, but they can get "manageable" power by riding at 8000-10000 rpm and up, where the power curve is less steep. Upstairs in the rev range, the Gamma comes off trailing throttle in a corner and back on power crisply. Wham, hit, snap, whew! Your own breathing difficulties aside, you'll have the Gamma hauling so quickly and so fast after three or four corners, you won't dare to continue! Ride the bike into the 7000-9000 rpm range, and you're in the powerburst minefield of the rev band. As unsettling and unmanageable as the Gamma is in the tight stuff, it's best just to forget those knotty little canyon roads. Ninja's, FJ's FZ's and other sport bikes won't really unload the front end when accelerating out of corners. The RG500 does, and the rider must pay attention to where the airborne front wheel is pointing when the corner starts to open up. Cock the wheel sideways when it's airborne, and as the tire makes full, firm contact with the ground below the bars will reward you with a healthy shake. The shake passes in a moment, though hardly unnoticed by the rider. Dust and dirt in the exit line of a corner might well command the rider's attention also. The powerburst requires vigilance with regard to traction, even on clean roads. Please note that the Gamma, nose light while accelerating off a corner, would become, ah, problematical should the rear tire spin loose. Given the RG's steep power curve, the two stroke's revs jump 1000 pr so (and about 12 horsepower) before a rider can react. By instinct he wants to snap the throttles down; by knowledge, to back gradually out of them. Steep zippo flywheel effect, make backing out delicate and difficult. Get the picture? Short connecting straights between your favorite corners fold into their centerlines and vanish. With another bike your mind might rest along such places, but the Gamma gives little peace here. Under hard acceleration the front is always light. The front tire, even in the upper gears, seemingly skims the pavement. The RG squats back on its haunches. the front end extends, slowing down the steering and putting the Gamma in its most stable attitude. Comforting, yes, but remember a front wheel trying to go airborne feels very light. Bang the throttles shut and jump on the brakes. the brakes, you conclude are at first, fabulous. Eight live pistons jump to your bidding in the two front calipers, and two service the tiny rear disc through the rear caliper. The rear brake is just superb. It's progressive and not too powerful. That's good---a panic stricken locked front rear wheel would have the RG rider just a kiss away from the emergency room nurse. The front binders are powerful, predictable and impressive, yet the Gamma's blinding approach to corners make the brakes, after a while, feel merely excellent. Braking dives the RG's nose down hard, and here the anti-dive system keeps the bike in a reasonable attitude. You'll not forget that the Gamma has a steep fork angle. You'll get irritated at yourself a you continue to turn the Gamma in too soon, cutting corners too tightly, when you could have run the bike in deeper, clicked it over later and still had road to spare. In its nose-down attitude the Gamma sweeps over bumps without fluttering the bars ominously. While bumps often enrage motorcycles with steep head angles, the RG remains stable and composed over rough pavement, even with the front suspension loaded. Nevertheless, the 500 always responds now to rider input, and the RG pilot shall in all cases, remain smooth and graceful. Specific riders fit the Gamma to themselves just like a custom set of leathers. Here's one setup as assembled by 130 pound rider Daniel Coe. Anti-dive: number one position. Fork air pressure: six psi. Fork spring preload position: one-point-five (one is the lightest). Fork tube position: tubes dead even with the topside of the upper triple clamp. Rear spring preload: one-point-five. Tires: front, Dunlop 120/80-16 Sport Elite, RS compound; rear, standard issue Michelin M48 120/90-17. This front end configuration satisfied DDC; suspension, tire, settings, everything except the fixed position handlebars. Coe would have modified the bars, moving them down and outward slightly for greater comfort and leverage. Coe couldn't get too prescriptive about the rear suspension because he hadn't settled on a final tire choice. Right now, if he could, he's soften the rear spring, using less preload, and boost rebound damping. That's impossible with the Gamma shock, adjustable only for spring preload. In a perfect world the RG would have a totally adjustable shock, so that springing and compression could be orchestrated. The front Dunlop was in place for the braking tests. That and the phenomenal brakes, explain a topping distance of 111.33 feet from 60 MPH. Just as a point of comparison, the GS1150 Cycle tested in May of 1984, required 129 feet. Don't even bother looking at other 500cc bikes for comparable quarter mile times. The RG ran 440 in 11.37 seconds at 120.08 MPH. Coaxes by DDC's Grand Prix bike experience to produce some perfect launches, the Gamma would loft and carry its front wheel all the way through first gear. The next quickest 500 we've sampled is the RZV500R yamaha at 11.77/117.77 MPH. The 750 sport bike closest to the Gamma is Yamaha's FZ750. To absolutely, positively go quicker in the quarter mile, you'll need a 900/1200 Superbike. Heaven help us, the Gamma is just too intense a motorcycle to ride on a daily basis. You should approach the RG only when your biorhythm charts say your waves are right for it. Unfortunately, the RG will never be right for the EPA, wet blankets intolerable of two stroke exhaust effluent. This circumstance is less tragic than you at first might think. Suppose you made a GSX-R 750 with Gamma-like light switch power and the same performance and intimidation factor. Surely, most customers if given a choice would opt for a more "normal" bike with easily modulated power. Or, put another way. if Suzuki could federalize the RG the bike would need a broader, softer powerband for the company to sell more than a handful as curiosity pieces. If you're one of those Gamma owners, pick your roads as carefully as you monitor your biorhythms. We'd specify an open, fast winding two-lane blacktop that you know like your mothers handwriting. Intimate knowledge of the road lets you concentrate on the RG, get into the engine speeds the Gamma enjoys, and generate ground speed that will eventually bring you eye to eye with a county judge. We would stipulate a 150 mile loop, with no backtrack routing. Although the RG's riding position and ergonomics suit much longer days, your mind will go limp way before your body. In fact, if you ride the Gamma the way it loves to be ridden, 150 miles will leave your mind absolutely wringing wet from exhaustion. And frankly folks, we wouldn't have the Gamma any other way! RG500 Gamma Service Tips My New Gamma and its Evolution www.klouseau.com www.250ninja.com Web page created by Gammagir1 on March 25, 2001