History of the Suzuki
1985 - Something wicked this way comes . . . . the first of the GSX-R750s
In addition to being built to compete in the various worldwide championships, the GSX-R750 was Suzuki's attempt at building the ultimate street-legal race bike. The GSX-R750 was introduced at the 1984 IFMA motorcycle show in Cologne, Germany. Although th e GSX-R750 was available in 1985, they weren't sold in the United States until 1986. Competition was fierce in 1985 as Honda had their VF750, Yamaha had their FZ750, and Kawasaki had the all concurring GPz750 Turbo. There was some controversy about the GPz750 Turbo. Back then, Kawasaki ran an ad campaign featuring Pee Wee Gleason's 10.71 quarter mile pass on a supposedly stock GPz750 Turbo. Unfortunately, none of the magazines of that era could eek out anything faster than an 11.8.
Sticking to Suzuki, the original GSX-R750 is considered legendary. It had a lightweight aluminum alloy double-cradle perimeter frame, a 55° leaning angle, 29mm flat slide carbs, dual front discs with 4-piston calipers, and 18-inch wheels. Back in '85, t his was race bike gear.
Reducing weight was the goal at Suzuki. This took them in a different direction than their competition was following. While other manufacturers used steel frames, Suzuki chose aluminum. The original GSX-R750 frame weighed 18 pounds. Despite their long history of liquid cooled engines, and the fact that others were using a liquid cooled design, Suzuki decided to go with an air/oil-cooled engine design. These attempts to save weight over water-cooled competition worked. The GSX-R750 weighed over 70 pounds less than the FZ750, almost 100 pounds less than the VF750, and over 125 pounds less than the GPz750 Turbo. The payoff was speed. The GSX-R750 was as fast as the FZ750 in both the quarter mile (11.2) and in top speed (145). The VF750 was a distant t hird with an 11.9 quarter, and a 138 MPH top speed. Depending on who you believe, the Kawasaki was ether the fastest, or not.
1986 the GSX-R750 arrives stateside
The original GSX-R750 had a unique air/oil cooling system. Suzuki used a dual stage oil pump that they referred to as SACS (Suzuki Advanced Cooling System). The first part of the dual stage pump directed oil in a normal fashion. The second stage of the pump was used to deliver oil to high-volume nozzles which used oil spray to cool the engine. This design didn't produce as much horsepower as the five-valve Yamaha, but the reduced weight more than made up the difference.
The February 1986 edition of Cycle Magazine stated, " . . . the GSXR GSXR steers with remarkable lightness, handles even sand-strewn, bumpy corners with confidence-inspiring predictability and accuracy. Crisp carburetion makes throttle transitions smooth and controllable". Later in the same article they stated "Significantly, less weight allows the bike to perform engine wise at the same level as the more powerful FZ. This Suzuki convinces us that the future is low mass. The puzzling thing about the GSXR is its 'racebike' format. The GSXR's riding position demands total commitment from the rider, and maybe that's why Suzuki labels the GSXR a racebike for the streets."
The GSXR also looked like a race bike. Back then, the only bikes to use dual headlights were endurance racers. Also, the rest of the industry was using 16 inch front wheels. Race bikes used 18's, so the GSXR got an 18. Those original GSX-R750's also c reated a buzz by weighing in at less than AMA Superbike minimum. According to Suzuki, they had a dry weight of 388 pounds. They used acronyms to add to the excitement. In addition to the previously mentioned SACS, GSX-R750's had NEAS/PDF. This stood f or New Electronically Advanced Suspension / Positive Damping Force. The basic premise of the system was when the brakes were applied, oil passageways within the front forks were closed off. This reduced nose dive. Out back, a steel bodied shock absorber was used with full floater progressive linkage.
If all that hype is enough to temp you to find and resurrect some Canadian-spec 1985 Gixxer, you may want to finish the article first. A few items may cool you down a bit. First, that rear shock was famous for overheating and fading. Second, the frames of that era flexed a lot. Lastly, the '85 models were known to be twitchy. The US models arrived as 1986's, and they had a longer swing arm, which made the bike a little less nervous. They also got bigger carbs; 31 mm flat slides versus the original 29's.
1987 minor improvements
In 1987, the GSX-R750 again got bigger carbs (34 mm versus the old 31's), bigger brake rotors (310 mm rather than 296 mm), and a new header pipe. This resulted in slightly more power, at a slightly higher cost; $4899, versus $4489.
1988 a complete makeover
In 1988, the GSX-R750 was completely redesigned. The frame was patterned after the Suzuka race bike. The frame's upper beams were thicker, and wider apart. The new steering stem was increased 20 mm to 80 mm and was the foundation for a much steeper ste ering geometry. The forks were also larger at 43 mm and had adjustments for spring preload, compression, and rebound damping. None of the other Japanese sportbike manufacturers came close to offering these features. Out back, the new swingarm pivot was cast into the frame, rather than welded in place. This was supported by a new gas charged rear shock. The wheels were considerably wider than anything else in that class. The front wheel was three and a half inches wide, with a four and a half inch wi de rear. The three spoke hollow wheels were suspended by tires specially developed by Michelin for the GSX-R.
Aside from being more rigid, the wider frame beams supported a more powerful engine. The new powerplant was a clean-sheet-of-paper, short stroke design. The new engine rev'd to 13K and was fed by a much larger airbox. Suzuki used this as an opportunity for another acronym, calling it the SCAI - Suzuki Condensed Air Intake. The larger airbox fed 2 mm larger carbs (Suzuki called these 36 mm carbs "Slingshots"). The new carbs fed larger valves, which were controlled by cams with more lift and duration. From there, the intake was passed to a new higher compression combustion chamber, where it was fired off by a new digital ignition system with dual electrode spark plugs. Exhaust duties were handled by a new four-into-two system. The engine was cooled b y a higher capacity oiling system, with a larger cooler, and higher flow oil lines. The new engine sat lower in frame, which decreased the center of gravity. That center of gravity was further decreased by the wider, lower gas tank. Measuring from the top of the faring, the 1988 model was 3.3 inches lower than the bike it replaced.
Now for the bad news. First, the weight. The new engine was 11 pounds heavier and the new frame added another 15 pounds. On top of that, there were the bigger wheels, tires, and exhaust system. This increased the weight by 40 pounds. On top of that, the lower center of gravity resulted in less cornering clearance.
Despite the bad news, the 1988 was a faster bike than the previous model. This was true of both the race bikes and the street bikes. On the racing front, in 1988 Doug Polen won the AMA 750cc Supersport Championship on a GSX-R750. On the street side, Cycle magazine reported " . . the new bike did everything more quickly and easily than the old; Stop, go, turn, and drag the ground".
Suzuki addressed some of the problems of 1988 in the 1989 model. To add some clearance, Suzuki moved the shock's upper mount 4 mm lower, and they used fork tubes that were 6 mm longer. Other changes included different transmission gear ratios, a four-wa y adjustable brake lever, and stainless steel covers on the exhaust canisters.
1990 another complete makeover
1990 brought another brand new bike. The new frame was once again wider and stiffer, the swingarm was both longer and thicker, the rear wheel was wider, as was the tire, the rear shock used an aluminum body and had a reservoir, and the front brake rotors were thicker and slotted versus the old model's drilled units, the rear wheel was an inch wider, with wider rubber, and then there was the engine.
For 1990, Suzuki went back to a long stroke design. This was mainly due to "issues" with the short strokers. One problem was the 1988/89 short stroke engines didn't have the low RPM torque of the previous generation Gixxers. To those who've looked at e ngine design, that's no revelation. What those short stroke street engines did have was great peak power. Unfortunately, the race versions didn't have as much power as the 1987 and earlier engines.
The solution was to design a long stroke engine that retained the short stroker's peak power and redline. That opened the door to a problem of piston speed. The long stroke and high redline brought the piston speed of the street bikes up to race bike le vels. To reduce bottom end stress, Suzuki lighten the rotating assembly. They used light weight pistons with a new coating called Alumite. They also used new rods and rod bolts. Ordinarily, rod bolts have nuts. For the new engine, Suzuki threaded the rod bolts into the rods themselves. This saved the weight associated with the nuts and washers.
Another problem with the 1988/89 engines was that they developed cracks between the sparkplug threads and the valve seats on the combustion chamber side (and Porsche owners thought they were the only ones with that problem). Suzuki addressed this by using smaller, 10 mm sparkplugs.
The old short stroke engines were fine for the street, but the racing versions ran hot. To ensure that didn't happen again, Suzuki used the GSX-R1100's larger, curved oil cooler. The curved oil cooler had the benefit of more surface area without requiri ng a wider space to mount it. Suzuki reported the new oil cooler was 48% more effective. To address the oil windage issues usually associated with the higher crank speeds, Suzuki used a deeper oil sump.
Outside of California, the new bikes got larger carbs. The new units were 38 mm. In California, the smog police determined 36's were big enough. In the U.S, the new carbs came with a blank power jet. Suzuki disabled the system by installing a blank, or zero ('0') jet. I'm not sure why Suzuki did this. Maybe they knew a good percentage of GSXR owners tossed their airboxes in favor of individual air filters. Those who kept their airboxes simply had their favorite tuner jets install a power jet and change the main jet circuit. The issue of ground clearance was addressed with a new four-into-one exhaust.
The results were spectacular. In addition to handling and braking better than the previous model, the 1990 GSX-R750 was a 10 second quarter mile bike.
1991 some bodywork, some head work, and some weight
The 1991 model wasn't all new, but there were a lot of changes. First the bodywork was all-new. This was the first year of the headlight cover. When coupled with the more aerodynamic tail section, drag was significantly reduced. Suzuki also installed upside-down Showa forks. This was an industry first for street bikes. The new forks aided handling, especially during braking.
The engine was revamped. Or more specifically, the head. Previous GSX-R750 engines were sixteen-valve engines. The valves were actuated in pairs by forked rocker arms. For the 1991 model year, Suzuki went another direction. They still used rockers, but each individual valve had it's own rocker, which was in turn impelled by it's own cam lobe. Valve lash adjustments were also changed to shims. Other head changes included altered cam timing, modified porting specs, use of the GSX-R100's heavier valve springs (another reason the forked rockers were disposed of - the heavier springs would induce flex), and reshaped combustion chambers.
The head changes didn't make much difference for the street bikes. They picked up an addition 2 HP. Unfortunately, the changes added another 20 pounds.
1992 New graphics on the leftover model
1992. While the rest of the world received the new water cooled GSX-R750, the U.S. got leftovers and bad graphics. At the time I thought the paint schemes were hideous. Then 1993 rolled around and things really got bad.
1993 you may want to cover your eyes
1993 was the U.S. debut of the water cooler. The racing teams felt they had been hurt by the weakness of the old model's cooling ability. Kawasaki had taken the AMA 750cc Supersport championship for the previous three years and Suzuki was finally making a change. These new models had twice the cooling capacity of the old model.
Suzuki also revamped the rest of the engine. Rocker arms were no longer used as the cam lobes controlled valve buckets. The valves themselves used narrower stems. The valve angle was narrowed, the compression ratio was increased, and the pistons were lighter. The engine itself was physically more narrower, and the factory made another go at mounting it lower. This time there weren't clearance issues. The frame was revised. It was now lighter and more rigid than the previous year. The swingarm was also lighter. The steering geometry was altered, and the wheelbase was increased. This was truly a new bike.
A GSX-R750 dethroned Kawasaki's ZX-7R and won the AMA 750cc championship, but the street bikes were down on power from the previous year. They also weighed more. In fact, the 1993 model weighed 100 pounds more than the original U.S. spec 1986 model.
In speaking about the 1993 model, Cycle World wrote, "The Suzuki's dyno numbers are a disappointment," and ". . . liquid cooling has not brought an increase in performance." Personally, the graphics were the low point. I couldn't stand to look at them.
1994 it may look the same (or worse), but it really is different
For 1994, Suzuki responded to the complaints. Once again, the GSX-R750 was a new bike. The engine was completely redesigned. The cylinder liners were discarded in favor of a nickel/silicon/carbide cylinder coating. This had the dual benefit of reducing weight and overall block dimensions. The cam drive was moved from the center to the right side. This allowed Suzuki to eliminate one main bearing (to five from six), which also made the engine more narrow. The engine placement was also modified so as to allow transmission work to be performed without dropping the crank. The smaller engine was wrapped in a new frame and was fed by 39 mm downdraft carbs.
This new bike had the same dimensions as Kevin Schwantz's race bike. They both had 3.9 inches of trail, 24 degrees of rake, and had a wheelbase of 55.1 inches. The new bike got lightweight forks. A braced swingarm, lightweight six-inch wide wheels, lighter brake rotors, and a two-piece removable subframe that was controlled by a piggyback style shock. The wet weight of the 1994 model was about the same as the 1986 model.
The 1994 suspension and drivetrain was good enough that Suzuki left them as is for the 1995 model year.
Unfortunately, there were a couple of problems. In my opinion, Suzuki's ugly graphics reached their peak with the 1994/1995 models. Secondly, there was a recall due to insufficient piston to valve clearance. A thicker head gasket was the fix.
1996 Suzuki returns with a vengence
1996 brought another all-new model. This year the frame was changed from a double cradle to a twin-spar design. The new aluminum frame wrapped around another short stroke design 72 mm x 46 mm). The cylinders featured a silicon carbide electroplate coating, and the engine was tilted 25° forward. A new induction system called SRAD (Suzuki Ram Air Direct) was implemented with Mikuni 39 mm BDSR (downdraft "R" slide CV) carburetors. In order to keep the weight down, magnesium bits abounded.
The press loved the new bike. The May 1996 issue of Cycle World featured an article entitled the "Ultimate Sportbike Challenge". This article compared the GSX-R750 with Ducati's 916, Honda's 900RR, Kawasaki's ZX-7R, and Yamaha's YZF750R. Aside from costing less than every other bike, the GSX-R750 made the quickest quarter mile pass, had the highest top speed, shortest stopping distances, had the second fastest lap times at Willow Springs Raceway (0.02 second slower than the 916) and placed third in the roll-on test. Cycle World said, ". . . the Suzuki GSXR750, the closest thing yet to a street-legal GP bike." Of the GSX-R750, Motorcycle Consumer News wrote, ". . . open-bike power, middleweight handling and superb attention to detail, it's really in a league of its own, and the unquestionable winner here."
1997 like day-old pizza, the leftovers are still good
The 1997 model was basically the same. The thing that really stands out is; sanity has returned and the ugly graphics of prior years were disposed of.
1998 Fuel Injection
At the press introduction, Suzuki said they had gone as far as they could with carburetors, so 1998 ushered in the EFI era. The GSX-R750 used a system that was similar to the one used by the TL1000S. One Mikuni injector per cylinder, a Denso ECU and sensors, and 46 mm throttle bodies. The new FI system introduced a problem involving abrupt throttle response. This was typically corrected by remapping the ignition and fuel curves with an aftermarket ECU module. New modules were also required for aftermarket exhausts (much like jet kits for carbs)
Other engine changes included cams with higher lift and more duration. A two stage airbox with a single flapper valve was used to improve midrange punch (Hmmm, that was shortly after Mercedes-Benz released their two stage intake manifold). The exhaust system was revised. In an effort to save weight, a thinner primary drive gear was used, and a #525 chain replaced the #530.
The bike got thicker brake rotors. The previous rotors weighed less, but their longevity wasn't a strong suit. The wheelbase was also shortened by 5 mm. Spring rates and damping were revised and a problem that caused the rear shock to overheat was addressed.
The only changes for 1999 were new graphics.
2000 Hide the women and childred
The 2000 model was completely redesigned. The frame was all-new and weighed 4 pounds less than the previous model. It was 4 mm shorter in height, 8 mm narrower, and 15 mm shorter in length. The swingarm was 20 mm longer, yet almost 2 pounds lighter. Although the swingarm was 20 mm longer, the wheelbase was only increased by 15 mm. That was due to reduced engine length.
The new engine was more compact. It was 15 mm shorter in length, 8 mm narrower, and 11 pounds lighter. The head had 12° intake valves and 13° exhaust valves. Each were one degree more narrow. This made for a more compact combustion design. The compression grew to 12.0:1. The narrower tracks allowed for a narrower cylinder head, which now had a magnesium valve cover. The bottom end went on a diet of lighter rods, crank, valve springs, cams, alternator, head casting, and wrist pins. The cylinders we re cast as a single unit with the upper crankcases. This had the dual benefit of lower weight and greater strength. Also, as is the case in the automotive industry, Suzuki did away with external oil lines and cast oil passageways through the block and head.
The fuel injection system was redesigned, eliminating the abrupt off/on throttle transitions. This was accomplished by using a second set of ECU controlled butterfly valves that keep intake velocity high, dramatically increased midrange power (this is sounding more like Mercedes-Benz' class leading intake all the time). This higher velocity intake also increased combustion efficiency, resulting in cleaner emissions.
The bodywork was more aerodynamic, as it was 30 mm shorter in height. To increase steering quickness, the rear wheel width was reduced to five-and-a-half inches with a 180/55 tire. The front end geometry remained the same as the prior year.
This GSX-R750's weight loss program wasn't restricted to the engine and frame. Four-piston front brake calipers replaced the heavier six-piston units. The wheels were lighter, as was the bodywork, rear shock, and forks. The 2000's wet weight was less than that of the 1986 model.
Graphics changes only.
A new adjustable swingarm provided adjustments for height. The fuel injection maps were changed and a cold start idle feature was added. The fast idle lever was eliminated. When the headlight low beams are on, both headlamps remain illuminated. The head pipe is polished and the mirrors were changed.
Graphics changes only.
So why stop here? Suzuki continued to build the GSXR750, but 600's killed any interest I had in them. The 2005 Kawasaki ZX-6R (636) ran 10.38's in the quarter at 135+ MPH. The 2004 GSXR750 ran a 10.36 at 135+ MPH. The 750 was more powerful. Stock, the GSXR had ten HP and ten ft-lbs of torque over the ZX6. However, the ZX6 jumper mod reduces that advantage to something between zero and five HP. On top of that, the GSXR weighed more. That isn't to say the 750 Gixxer was a bad bike, just that "I" lost interest.