An accurate rendering of superbike history demands that Suzuki’s 1100cc four be included. Taking its place on the throne previously held by Kawasaki’s DOHC Zed, the first issue 4v ascended during a time when pundits warned the same environmental watchdogs that neutered Detroit would soon claim motorcycling. Historical fact shows the industry had other plans, and a big part was Suzuki’s 1975 mandate that made chassis a priority. Pushing past other Asian open-classers in 1978 using formulas developed in Britain and Europe, credit goes to Suzuki for the sum of its components. We begin in 1980, when more thrust was added and the GSX1100 ‘Lunchbox’ established a stunning new standard of excellence.

Just the fact you’re reading this proves the writer has successfully maneuvered some lofty moto-distractions. Not easy, and certainly no complaints, as these words serve to acknowledge the owners and riders who have taken time to send material. Every one arriving with a story that needs to be told, this shared enthusiasm boosts the catalog of historic motorcycles featured here. Right now, as words are grouped to define Suzuki’s extraordinary climb up the 80’s superbike ladder, there’s an eye on the Lunchbox and another peeking at Motoplast specials, Münch Fours, 500 Pantahs and more. All included in future updates. Featured here, Graham McMullan’s silver-blue GSX1100 perfectly illustrates the Euro-spec controls and graphics not afforded to Suzuki’s US buyers. This original paint gem was recently recommissioned, and noting the various Lunchbox-based resto-mods in my database, it isn’t a motorcycle that needs wholesale changes. Still, I get it. To my eye, that leading axle fork, aluminum swingarm and criss-cross cast wheels are critical design elements. Making a point and with respects to MV Agusta’s 600cc four or even Ariel’s square 1000, this writer believes in 1966 the Mammut became motorcycling’s first modern superfour. Not just bigger, the Münch’s ground pounding DNA spins in the rapid GSX. Yes, most certainly refined after fourteen years of production practice, but close relatives in the post-1964 superbike lineage.

As it usually goes with great designs, Lunchbox excellence stems from its development. Possibly hearsay but probably not, I’m told on good authority of the intensely competitive rivalries between members of Japan’s Big Four. How else to explain the plethora of engines large to small, and in varying cylinder counts? New classes, sub-classes, cruisers and rapidly developing two-stroke/motocross hardware all pushing against all sides. For Suzuki, the open class sales target was painted Honda red but the Z-1 proved more inspirational from an engineering standpoint. By 1980, there was nothing Suzuki or anyone could do about Kawasaki’s world dominance – its astonishing performance and durability gave the engine an undeniable winning percentage. Stateside, we recall 1978’s global shootout where Suzuki’s 2v GS1000 lacked the headline stealing thrust of Kawasaki’s Z-1R Turbo or Honda’s CBX six, but in time and with distance, the GS1000 grew Suzuki’s world following considerably.

New in 1976, Suzuki’s four-stroke 750 is where the GS legend began; almost Z900 quick and debuting Suzuki’s superb new chassis. Loosely based on the 750, 1978’s GS1000 (this, a German import in light blue) used a revised frame due to its boosted output and extra braking force. Penning Suzuki’s RE-5 Rotary and GS750/1000cc platforms first, engineer Hisashi Morikawa was responsible for the GS1100’s athletic legs. How serious was Morikawa about fighting flex-induced wobble during cornering and braking? Start at the top of the GS’s twin cradle and note the steering tube is not only gusseted and reinforced top, side and bottom, but the top tubes are cross-braced no less than five times between the steering stem and seat edge. Period GSX1100 press coverage shows far less emphasis on the Lunchbox chassis, as editorial focus fell to the engine.

Well publicized, an excellent series of US road tests (Cycle, Cycle Guide and Cycle World) contain useful dialog from both Morikawa and engine design manager Sadao Shirasagi. Truly a point of emphasis, the GS11’s ability to sustain reliable power begins deep inside its finned crankcase. Five caged main roller bearings and two on each end support the pressed crankshaft, including two ‘unsupported’ mounts for lightness. Focusing on this component, Shirasagi gave candid answers regarding the pressed-together/forged debate. Suzuki’s investment in tooling to produce the GS1000 surely played a part, and “If a forged crank were used,” said Shiragi, “The rearward rod bolt on the number four throw would hit the clutch in the course of a crankshaft revolution.” To resist slippage the Lunchbox got larger crank pins, and by mid-1982 Suzuki addressed the twisting issue for good by spot welding them to the flywheels. Like the rugged Kawasaki, primary transfer is a helical gear driving a forged steel clutch basket.

Staying in the crankcase, more than one road tester mentioned the forward-facing oil pickup system (to prevent starvation under hard braking) sometimes caused the GS’s oil pressure light to flicker during power takeoffs. Repeated on several fronts and from several different tuners, this momentary loss of oil pressure (seemingly) does the roller bearings no harm. Or at least, less than a high-pressure plain bearing design. Thoughtfully, Suzuki fit “In” and “Out” marked plugged spigots on either side of the filter assembly for an oil cooler, sending the engine’s full supply through the cooling radiator (attached via pre-threaded lugs on the frame’s cross brace) oil filter, then pumped back inside. Tested twice in 1980, Cycle’s coverage included complains of drive lash – a problem (according to them) caused by less than optimal transmission gear design. I didn’t see this repeated in any other test. Otherwise sturdy, the Lunchbox’s 5-speed was generally uprated over the GS1000 with tougher and wider gears, bearings replacing bushings, and improved oiling.

Precise and strong, the GSX1100’s bottom end provides an ideal foundation for Shirasagi’s TSCC magic. For years I’d lazily dismissed Suzuki’s ‘Twin Swirl Combustion Chamber’ as just another in a long line of silly Japanese acronyms, seemingly everywhere. Studying deeper revealed this engineering concept shaped both piston and cylinder head construction, per a period technical essay written (I assume) by Kevin Cameron. “There is nothing new about 4-valves and double overhead cams in 1980,” Cycle World accurately stated. “What makes the GS1100 different?” Those answers came in a review outlining Shirasagi’s considerable challenge of producing dominate power while returning acceptable fuel mileage and emissions compliance. The key? More efficient combustion. Every engine has its own unique patterns, but in basic terms all gas/air mixtures tumble into the combustion chamber. In time, tuners everywhere discovered more mixture ‘agitation’ pushes the piston down faster when ignited. Without adding one single moving part, TSCC enhances this process; swirling twin plumes of gas and air into fire “at the same rotational direction as the tires.” This built-in efficiency mixed flat pistons, compact combustion chambers and optimal valve timing, location and size.

(Sharing Suzuki’s combustion and cylinder head detail not only illustrates some clever designs, but Cycle Magazine’s thorough journalism coverage too. With its flat-top piston the combustion chamber is compressed considerably. Central spark plug location is reported to improve the combustion process as well. Locknut valve clearance adjustment was an added benefit, saving money and time by not needing adjustment shims. Images: Cycle magazine)  

Starting its four-year dominance, the Lunchbox ripped through the 1/4-mile in 11.49 seconds, averaged over 41-mpg, and pulled fifth-gear all the way to its mathematical (US gearing) top speed of 140-mph. Other than the fed-mandated 85-mph speedo and restrictive exhaust there’s little emissions gear; no fresh air tubes or funny airbox plumbing. Even the engine is solidly mounted. No rubber. Happy to drone long interstate miles, zip across town or run full-berries through the change up, Suzuki’s swirling gasses efficiently boosted midrange and peak power. Yes, the GSX1100 remained among the fastest available until 1984, but it was the Lunchbox’s flexibility that won so many over. Modest amounts of cam lift/duration and (9.5) compression, small valves (27/23mm intake/exhaust) allowed it to rule as an easy to tune all ’rounder. Credit TSCC for the engine’s owner-friendly screw/locknut valve adjusters too, implemented mainly to reduce overall engine height due to the (nearly vertical) included valve angle. To my knowledge, all versions fit 34mm Mikuni CV carbs in lean jetting, 4-into-2 exhaust, and Suzuki’s inductive ignition.

(Debuting on 1976’s GS750 and updated for 1000cc,, Suzuki made no wholesale changes to the 1100’s steel tube frame. Braced and crossbraced throughout, the engine is solidly mounted. Hollow aluminum swingarm mixes extruded and forged pieces, cleanly welded together. Built from the inside out, Suzuki’s dedication to chassis integrity and its legendary 16v engine took the Lunchbox into superbike superstardom. Images: Graham McMullan)    

My press research uncovered info stating the production prototype was rejected at a dealer’s meeting, due to its styling. I’d love to get my hands on images of that! Taking editorial license, I see the Lunchbox’s rectangular nacelle as a bow to the XS-Eleven and that long, comic book tail a raised finger for those who criticized their RE-5. Kawasaki responded in 1981 with its range leading, square-lamp GPz 1100 Zed. Among the big, open class four strokes Kawasaki and Suzuki were pulling away in the homeland, but no lead was safe. Long a favorite based on content, Cycle magazine named Suzuki’s GS1100 “The King” – that title previously reserved for the Z-1. If ever becoming lucky enough to own, mine would likely look just like Graham’s UK import in silver/blue. Monotone with small stripes and tall bars for the US, UK/Euro market machines showed several main and secondary colors, sports handlebar, and (unconfirmed) taller gearing. The lamp is reassuringly bright at night, and the clocks glow red.

(The Lunchbox displays classic drop-spear styling…with a twist. UK and Euro editions vary in graphics, seeming different market to market. Foot rests and controls are uniform, US models fit with the higher ‘Western’ bar. Protruding taillamp is comic book cool…and a familiar sight to the competition)     

Selling well then, finding your own Lunchbox Suzuki 1100 shouldn’t be that hard, but it’s sure harder than it used to be. Please excuse the lack of a hard baseline value, but it does seem $5000 USD will bring a runner home. Like anything, you’d be miles ahead buying from a loving owner, and those usually have the contacts you’ll need. For collectors, the reality is most GS1100 fours lived a hard life, but the basic durability of the design has kept many in use. There’s bound to be hundreds stashed away, so opportunity waits for those paying attention. All things being equal, the cost isn’t much considering its place in history and a bike that can still be ridden anywhere. Impressive for sure, and perfect for the superbike purist who enjoys a barking 4-into-1, some light customizing, or tuning. But for so many, the 1100cc Lunchbox was perfect just the way Suzuki made it. Nolan Woodbury

~Gallery~

Both a personal favorite and the subject of extended editorial focus, many GSX 1100 files have been contributed or collected over the years. Too many special ones for this space, so consider this gallery of stock and modified Lunchbox Suzuki’s a highlight reel – portrait and detail. More information is needed regarding color and graphics for specific export destinations, and tuning differences including control options, gearing, or even factory racing kits. Very clearly, the UK/Euro market GSX offered far more color options. Here’s to wondering what else I don’t know? NW