Gsxr 750 Y

Info and history of the motorcycles Suzuki Gsxr


Gsxr 750: welcome back to literland

Mat Mladin and Yoshimura Gsxr 750-1000Yoshimura Gsxr 750

Mat Mladin and Yoshimura's success in capturing the AMA Superbike crown in 1999, together with extremely strong sales of both the Gsxr 750 and the new, right-size 600, was evidence that Suzuki's engineering staff and market planners made the right decisions in returning to a light, elemental sportbike for the generation that arrived in 1996.

Given such success, Suzuki moto might have chosen to rest, to give the engineers and designers a day or two off and bask in the glory.
Many other manufacturers have done so, allowing a groundbreaking product to soldier on with minor updates for several product cycles.

Yoshimura Gsxr 1000Katsuaki Fujiwara joined the Alstare Suzuki Gsxr team The danger in that approach, though, is not just the risk of being overtaken by the competition but also the real possibility that it will cost more to jump back into the fight from a weak position than it would to keep the pressure on. Suzuki moto, most emphatically, did not rest.

Scarcely halfway through the previous bike's production run, Suzuki moto began work on the 2000 Gsxr 750 with a few simple goals: make it lighter still (having rediscovered the benefits of low mass all over again), make it faster, and make it handle better.

Suzuki Gsxr 2001Gsxr's faceConsidering the dramatic improvements of the 1996-'99 models over their predecessors, a big leap would not be possible.
Already, the Suzuki Gsxr led the category in high power and low weight, and it didn't look like anyone else was ready to jump back into the 750 cc class.

Indeed, Kawasaki continued to race the ZX 7 R but did not lavish any development on the street version.
Yamaha had long since left the class, and Honda remained with only the sport-touring VFR, because the new RC 51 was in place for AMA Superbike and World Superbike competition.
With the V-twin Tl 1000 R racing project shelved, Suzuki moto continued to push the Gsxr 750's capabilities for racing for the elite level, as well as to improve chances for the many privateers who campaigned the Gsxr in Supersport and Superstock racing.

The new Gsxr (600-750-1000)Yoshimura Gsxr 750 Even as the market continued to push for a two-class sportbike hierarchy-600s and 1000s-the company remained true to the 750. "Many times [the product planners in Japan] asked about the possibility to stop making the Gsxr 750, but I was firm with them.
It is our heritage and we will continue," says Motoo Murakami, executive vice president of American Suzuki and the former head of Suzuki Germany, a key man in developing corporate strategy.
Suzuki's penchant for doing more with less-combining technologies and sharing parts and development time among several motorcycles-was about to rise again.

Chambon with Gsxr Alstare SuzukiGsxr's stylingAlong with the new Suzuki Gsxr 750 came the predicted Gsxr 600 replacement based on the same platform, released a year after the Gsxr 750 to keep one from stealing the other's marketing push. There was also a surprise.
A big surprise. But we'll get to that later.
As always, Suzuki moto favored development of the Gsxr 750. It's natural. "We produce what we race" is something of a corporate mantra, and at the time AMA Superbike and World Superbike were both in the 750 cc fours/1000 cc twins format.
Suzuki moto then strove to produce an improved Gsxr 750 that would also make a competitive 600-no small feat in itself-and that could grow into a worldbeating 1000. But the Gsxr 750 came first, bristling with new technology.

Gsxr's illustrationGsxr 750In the search for lower weight and more power-delivered together to make improved performance, as ever-Suzuki revised the chassis, comprehensively reworked the engine, and added a new fuel-injection system that would, once again, cause the other manufacturers to take notice (and, to a great extent, to follow the same technological path).
In the end, the new Suzuki Gsxr became the lightest in the model's history-365 pounds dry, compared to the 395 of the original.
And it was the most powerful: while riders were enthralled with the 1999's 114 horsepower at the rear wheel, the 2000 model was better by 10 hp.
Barn! Just like that. Starting with the chassis, Suzuki moto once again tried to compact the motorcycle. (In fact, with some hindsight we can see this trend, which started with the '96 model, continue to play out. Each generation since the '96 had become smaller, lighter, more efficiently packaged. Even the 1000.)

Gsxr 750's fuel injectionGsxr's dual-throttle-valve injection systemThe 2000 model was nearly an inch shorter overall and a quarter inch narrower. The frame, though similar in appearance, was completely revised. It was shorter-the vertical distance from the bottom of the steering head to the swingarm pivot was reduced half an inch, while that measurement horizontally was trimmed 0.3 inch.
The height of the stamped-aluminum main spar was reduced 0.3 inch, as well.
Components were juggled; the crosspiece below the swingarm pivot that holds the lower shock mount was changed from an extrusion to a casting to save weight, which was partially offset by a new cross brace between the vertical ears supporting the sub frame and internal bracing between the massive swingarm-pivot casting and the main side spars.
The overall goal was increased rigidity, better crash tolerance, and reduced weight. Overall, the frame changes helped cut 4.4 pounds.

Gsxr's SDTV dual-throttle-valve injectionMore torqueSuzuki's racing success with the Gsxr 750 and broad customer acceptance caused the engineers to stick with the previous bike's general chassis dimensions. Rake remained at 24 degrees and trail at 3.8 inches, but the wheelbase grew 0.6 inch thanks to a longer swingarm that itself was significantly reworked.
Still braced, the massive forward deck was slimmed, while the lower cross bracing just in front of the tire was increased in size.
A new aluminum-body shock from Showa saved a pound all by itself despite having a larger, 46 mm damping piston. It's not everyday that you get a better piece - improved damping and durability - and have it weigh less, too.
Up front, the Gsxr 750's showa fork was revised, with more travel but less overall length, and placed in triple clamps 0.3 inch (7 mm) narrower. The top stem nut was changed from steel to aluminum.

Gsxr 750's fuel injectionControl scheme for the SDTV Bolting to this inverted fork were new brake components, a step back to four-piston calipers from the '99's six-piston versions. Together with lighter front discs, the brakes alone were responsible for nearly 2 pounds of lost weight. (The rear brake received an aluminum piston for reduced weight.)
Even the wheels came in for scrutiny: new, diamond-shaped spokes, a smaller 5.5-inch rear wheel wearing the now-standard 180-cross-section tire, and a redesigned sprocket/ cush-drive setup slashed 3 pounds from the bike.
The new bodywork-clearly still a Suzuki Gsxr but usefully modernized-also contributed to the weight-loss program. The fairing panels were thinner (2 mm vs. 2,5 mm on the '99) with fewer parts.

The twin-bulb headlight assembly used a single reflector and saved weight over the 1999s, and it moved the leading edge of the ram-air ducts closer to the center of the bike, for improved efficiency. Here again you can see Suzuki's wind-tunnel work arriving in the showroom.
Moving on to the engine: you could be excused for assuming, at a glance, that the 2000 bike's engine was a carryover item. In fact, it was almost completely new. Retaining the double-split crank-case-the crankshaft and transmission shafts are carried on two planes-the 2000 engine's bottom end was reworked to move the transmission shafts closer to the crank for an overall reduction in engine length.
The upper part of the crankcase, which had been two pieces in the previous Gsxr 600 and Gsxr 750, was now one, following what had become industry convention.

With this change, Suzuki moto deleted an external hose that provided oil to the top end and replaced it with an internal gallery, saving weight. Although the engine retained the previous 72 mm-by-46 mm bore and stroke, the pistons were forged instead of cast aluminum (thus lighter and stronger), and the wrist pins had tapered bores for yet more weight reduction.
Lighter pistons permit lighter components down the line; the connecting rods (now shot-peened for strength) were thinner and gripped 1 mm-thinner main journals. The crank was reduced in size a millimeter here and a millimeter there.
Even the cams came in for a weight reduction, with a larger inner diameter. They rode in a new head with reduced valve angles-now 25 degrees compared to 29 for the '99 bike-for a more compact combustion chamber and straighter intake ports.
The valves remained the same size but were closed by single springs for 2000 and had thinner stems.

By careful development of the head layout, it was no taller than before. Slightly smaller chambers netted an increase in compression ratio to 12.0:1 (up from 11.8:1). A side note on the head design: it now carried internal passages for the PAIR (pulsed air injection) emissions system.
Before, external lines led to flanges just above the exhaust port on bikes built for certain markets, such as California.
But with emissions regulations becoming stricter, all bikes would need some kind of air injection.
To simplify hardware and save weight overall, Suzuki moto made the change to the head casting. It slightly complicated the casting and machining of the head, but it simplified the number of external components and reduced assembly time.

All of these engine changes may seem minor in terms of producing horsepower, but they contributed to the whole and allowed maximum advantage to come from the Suzuki Gsxr's improved induction and exhaust systems.
The all-stainless four-into-two-into-one exhaust system wasn't much different except for a shorter muffler. But the injection system was all new. "I was originally told that this idea was not good and not to pursue it," says Kunio Arase of his concept for the Gsxr's unique twin-throttle-valve injection system. "But I felt it was a good idea, so I continued to work on it in my spare time and on weekends." Good thing he did.
At its introduction, the Gsxr's new injection was lauded as a great step forward, making electronic injection feel more like a set of well-calibrated carburetors. (Many riders disliked the instantaneous response of modern injection, which could really upset the chassis during hard riding, particularly with a high-performance, light-flywheel engine.) The key to this system was in maintaining good air velocity in the intake ports.

With traditional single-throttle injection, when the rider whacks open the throttle the air can nearly stagnate, causing a stumble. The slide on constant-velocity carburetors was designed to prevent this condition by partly blocking the intake tract and maintaining good velocity. But CV carbs can only react to intake flow, and they can sometimes be fooled.
Jetting was a fine art. In Suzuki's new system the secondary throttle valve resides just upstream of the rider-controlled throttle. The engine-control unit manages it with settings based on dyno testing. It cannot be fooled.
At the same time, the throttle bodies were revised with slightly larger outlets (on the engine side) and inlets (near the airbox) but slightly smaller (42 mm vs. 46 mm) throttle plates.

The injectors were re-aimed to set at 60 degrees from the main throttle-body axis instead of 32 degrees, so that the fuel spray hit the wide-open throttle plate at maximum power to help promote atomization of the fuel.
Before, the fuel did not come into contact with the throttle plate.
This double-throttle system was managed by a new, lighter (of course), more powerful computer that held eight distinct injection maps-two for each cylinder, one for light load, and one for heavy load.
The computer decided which to use based on throttle position, engine rpm, intake vacuum, and other parameters. At light load, the computer read the intake vacuum for a more precise indication of throttle position.

At high load, it excluded this input and relied on throttle position and rpm. The system also took into account vehicle speed, ambient pressure, coolant temperature (mainly for cold starting), and cues from the side stand and tip-over switches.
A new airbox fed this system, as well. The secondary throttle plates had the added benefit of reducing intake noise-especially during the official emissions tests-so the flapper valve used in the '99 model could be eliminated. (More weight savings.) The Gsxr also regained its renowned intake honk. When you think about the state of affairs in 2000, it's still amazing that Suzuki moto lavished so much effort on the Gsxr 750, even if you knew a reworked Gsxr 600 was coming. In any event, the new Gsxr 750 sparked a new round of appreciation for the class. "I don't mean to take anything away from the original Gsxr 750," explains Paul Dean, editorial director of Cycle World magazine. "But the 2000 model just got everything right.

It was fast, great handling, and gave me tremendous confidence. I think that bike was a true high point of the Gsxr 750's development." "The 2000 model was a major surprise, given that all the other manufacturers had basically left the 750 class," says Kent Kunitsugu, editor of Sport Rider. "The jump in performance was almost as great as the '96 model's progression, which surely took a lot of R & D resources that other companies would have diverted to 'more important' (read: 'better selling') models. It's pretty obvious that the Gsxr 750 is a matter of corporate pride to Suzuki moto. But for good reason: they are justifiably proud of the fact that the original Gsxr 750 was the bike that started the 'racer-replica' revolution."

In its first year, the fifth-generation Gsxr was as strongly praised as the original. It won numerous bike-of-the-year awards and often placed extremely well in competition with open-class machines.
Motorcyclist magazine named the Gsxr 750 the Motorcycle of the Year in 2000. It won Cycle World's Best Superbike award that year as well. When tossed into comparisons looking for ultimate handling and performance, it usually won outright.
Mat Mladin took the AMA Superbike crown again in 2000-albeit on the 1999 bike because the new model had not arrived in time for necessary testing before the season began. Once again, Suzuki moto dominated the stock classes and were the bike of choice for privateers. And yet there was more to come.