SR Archive: 1998 Suzuki GSX-R750 Road Test

The best never rest—In 1998 Suzuki improved their already stellar GSX-R750

This article was originally published in the April 1998 issue of Sport Rider.

1998 Suzuki GSX-R750 Test
A moving target is in our sights and it is the 1998 Suzuki GSX-R750.Photography by Fran Kuhn

The trouble with being number one is that you instantly become the mark. You’re the target that everyone aims at, and it can be pretty tough continually fending off all of your foes’ many challenges. Staying on top requires constant improvement to keep your adversaries from planting their crosshairs on you as a stationary target.

After laying waste to the competition in the 750 class with the introduction of the new-generation GSX-R750 in 1996, it would've been easy for Suzuki to simply sit around this year and watch the others try to catch up. And why not? The Gixxer is so much lighter, faster, and quicker than its nearest competitor that doing nothing would have been showing the others a little mercy. They could have just slapped on some BNG (bold new graphics), maybe changed a few minor details and called it a day. Unfortunately (for the competition at least) the word "complacency" doesn't seem to be in Suzuki's vocabulary these days.

When American Suzuki officials were explaining to Japan how happy they were with the performance of the ’96 GSX-R during preliminary product testing, the response from the factory technicians was “Wait ’til you see the latest version in a year or two; it’s even better.” Say what? How could they possibly improve on a bike that has set new standards for not only the 750 class, but the sportbike world in general?

Replacing the carburetors with electronic fuel injection might be a good place to start.

1998 Suzuki GSX-R750 steering damper
Although the conventional steering damper mount—boss welded onto the GSX-R’s left frame spar—instituted last year remains (left), Suzuki installed a damper underneath the steering head (right) on the ’98 EFI.Photography by Fran Kuhn

Although EFI is nothing new on sportbikes these days, Suzuki's new GSX-R750 EFI is the first modern, mass-produced (sorry, Bimota fans), in-line four- cylinder to feature this innovation. "Today's sportbikes have pretty much reached the limit with carburetors as far as performance versus emissions is concerned," says Suzuki PR man Mark "Excelllllent" Reese. Federal pipe-sniffers at the EPA are getting increasingly restrictive concerning unwanted exhaust by-products. Trying to meter fuel precisely enough to make power while still burning clean is becoming more difficult than ever. Squirting the fuel spray into the intake tracts via fuel injection, instead of the carburetor's antiquated reliance on the laws of physics to draw the fuel up through a tiny orifice, makes it easier for the engineers to control the mixture.

Fuel injection allowed Suzuki to dump the 39mm carbs in favor of throttle bodies sporting monster 46mm throats and increase the airbox capacity from 9.5 to 10 liters, along with a 50 percent increase in intake area. It also let them increase the lift on the intake cams, while adding more duration to both intake and exhaust cams—another basic power-boosting step. And all this without increased emissions. This is one of those rare cases where we can have our cake and eat it too. (Unfortunately, riders in California will probably be hamstrung in the intake cam department, due to that state’s more stringent emissions laws.)

1998 Suzuki GSX-R750 spring preload adjustment
The GSX-R still uses threaded collars for spring preload adjustment but spinning the collar with a hammer and punch on the new EFI model is far easier than in years past.Photography by Fran Kuhn

The exhaust system was altered to improve low- to midrange torque. The header pipe’s length was reduced by 20mm, with the collector pipes shrinking 1.4mm in diameter; a side benefit is a slight reduction in the exhaust’s overall weight.

Based on the same EFI system used on the TL1000S V-twin, the GSX-R's single-injector-per-cylinder unit employs a two-stage setup to control fuel flow. At low- to midrange rpm and under light loads, the system calculates injector duration (the allotted time the injector squirts fuel into the intake port) primarily from intake manifold pressure and engine rpm. Since the engine's intake pulses can be very erratic at low rpm cruising speeds, using manifold pressure to measure fuel flow is far more accurate than simply basing it on throttle position. Once the rider starts trying to stretch the throttle cables, however, the system then bases its decisions on data received from a throttle-position sensor and engine rpm. The ECM (engine control module which controls the injection timing, ignition timing and fuel pump operation) not only receives info from the aforementioned sensors, but also checks data from sensors measuring engine coolant temperature, intake air temperature, atmospheric pressure, and crankshaft and camshaft position. Kinda like having Erv Kanemoto riding along with you to keep the engine running sweet. (It appears you can also mount up an aftermarket exhaust with no magic "chips" required).

1998 Suzuki GSX-R750 front end
The front-end remains largely status quo on the EFI model, with the exception of stiffer springs and rebound damping in the fork, and thicker (5.0mm versus 4.5mm) brake rotors for resistance to fade. Different disc carriers with less rotor buttons offset the increased weight a bit.Photography by Fran Kuhn

The engine itself received a few updates as well. Keeping with the previous philosophy of shaving weight wherever possible, mods like a smaller primary drive gear (minus 40 grams), "waisted" crankcase bolts (same as the GSX-R600, cutting 200 grams), and digital direct spark plug caps (again, like the GSX-R600, slicing off 400 grams) were employed. A smaller 525-size drive chain replaces the previous 530 unit, while the gearbox ratios were tightened up from first to fifth, working with lower final drive gearing to improve acceleration.

The chassis and running gear weren’t left untouched either. The frame was reinforced at the rear suspension linkage area, while the swingarm pivot section was strengthened and made 320 grams lighter by switching from a sand-cast to a low-pressure casting process. Although the front brake rotors are heavier due to increased thickness (4.5mm to 5.0mm), that was countered somewhat by reducing the number of rotor floating pins on each side from 10 pins to eight. Both the front and rear suspension feature revised (read: stiffer) damping and spring rates with a unique “temperature compensating” system built into the rear shock’s rebound damping components. As the oil thins out from heat generated by hard use (like say, racing), that same heat causes an aluminum shaft to expand, forcing a needle farther into its “seat.” This restricts the oil flow, which corresponds to stiffer rebound damping. Tricky, eh? We can thank our dirt-eating, potato-growing brethren for this feature, which was heisted from Suzuki’s RM motocrossers.

1998 Suzuki GSX-R750 intake valve
A solenoid-controlled, intake “flapper valve” in the airbox is said to maintain correct airflow velocity for better low-rpm power; although it probably has as much to do with controlling intake noise as it does airflow.Photography by Tom Riles

The first thing you notice upon climbing aboard the new GSX-R into a normal street riding position is, whoa!—you can actually see the tachometer, instead of peering through the windscreen like last year. Suzuki slightly increased the angle of the windscreen’s “bubble” which also helps wind protection a tad, although your upper torso still collects the majority of the windblast.

Like any other fuel-injected bike, the EFI 750 fires up instantly on cold mornings. The choke lever is actually just a fast idle feature; the GSX-R can literally be ridden away after 30 seconds of warm-up. Once underway, you notice that another previous GSX-R trait has largely disappeared: the bucking and surging at light throttle/cruise settings caused by the carbureted version’s EPA-mandated lean fuel mixtures. The new injected GSX-R is just as content puttering along at 4000 rpm in city traffic as it is screaming up to 13,000 rpm at full throttle. Unfortunately, the somewhat excessive driveline lash of years past is still present on the new Suzook, and coupled with the fuel injection’s crisp throttle response off idle, it can make some on/off throttle transitions a pain. Also new this year is a steering damper mounted beneath the triple clamps, which unfortunately contributed to heavier steering in urban tight spots.

1998 Suzuki GSX-R750 windscreen comparison to 1996 GSX-R
This comparison with a ’96 model shows the higher “bubble” on the ’98 model (left), which offers slightly increased wind protection. It also allows a clearer view of the instrument panel in a non-tuck riding position, instead of forcing the rider to peer through the windscreen.Photography by Fran Kuhn

Of course, it’s when the motor’s wailing at 13,000 rpm that this here machine is happiest. Make no mistake, if you’re more concerned about overall comfort and highway roll-on power, this bike won’t be your first choice. There’s no getting around the basic characteristics of the engine’s design: a high-revving, oversquare powerplant that requires some skill from the rider to keep the revs up in the powerband. The Suzuki’s airbox has a “flapper valve” which is claimed to restrict airflow at low rpms (and maintain intake velocity) for better low-end grunt. But when compared with any other 750, the word grunt is more like whimper.

Still, midrange acceleration has improved a bit: The injected GSX-R is quicker than the carbureted model in both the 60­–80 mph and 80–100 mph roll-on tests by more than half a second. But we attribute this more to the lower gearing and closer-ratio gearbox than the fuel injection. It sure ain’t no Ban­dit 1200, but better a little than nothing at all.

1998 Suzuki GSX-R750 tailsection
The GSX-R’s tailsection “trunk” has been expanded a bit this year, with slots cut into the base to fit a U-lock. There’s enough room in there to fit a few small essentials as well.Photography by Fran Kuhn

Since the overall chassis and rolling stock have remained relatively unchanged, the GSX-R750 still delivers when the time comes to put the hammer down in the canyons. The close-ratio gearbox makes it easier to keep the engine on the boil, and a slight notchiness during around-town shifting all but disappears when the pace heats up. The same scalpel-sharp steering lets you put the bike anywhere you want in the corners, and the new Dunlop D207 Sportmaxes are a far cry from the merely adequate D202s they replace; these tires stick and steer superbly. Pay attention to gear selection in the twisty bits, and it’s kinda hard to argue with 115.7 horsepower propelling a low 400-pound package.

1998 Suzuki GSX-R750 cylinder assembly
The cylinder assembly features a “closed deck” design on the top mating surface. With less coolant passages to weaken the structural integrity, piston-to-cylinder tolerances can be tighter than normal—theoretically resulting in more horsepower.Photo Courtesy of Suzuki

It’s probably a combination of both the tighter-spaced gears and the fuel injection’s more precise carburetion, but the new Gixxer definitely comes off the corners quicker. Part of this could also be attributed to the injected bike’s friendlier powerband, which allows higher speeds and earlier throttle openings in the corners rather than the carbureted version’s nasty power hit around 9500 rpm. The new GSX-R sports a much smoother transition between supersonic and warp speeds.

Although heavier riders may notice the changes to the suspension damping and spring rates during spirited canyon sorties, the improvements are most apparent when the bike shreds racetrack pavement. Instead of cranking up the rebound damping to full stiff (and wishing for more) like last year, we found that about 3⁄4 turns from maximum in the rear and one turn from max on the forks proved optimum this time around. Slapping on a set of Michelin’s ultrasticky Race 3 compound Hi-Sport radials enabled us to push the performance envelope with confidence, highlighting the Suzuki’s continued racetrack prowess. We’ve sang the GSX-R’s praises since its inception, so suffice it to say that the new suspension keeps the chassis just that much more composed at serious blood-in-the-eye paces. It’s no wonder that the majority of bikes you see at club races these days are GSX-R750s.

1998 Suzuki GSX-R750 Engine
The addition of electronic fuel injection permitted Suzuki’s engineers to employ a few hot-rod tricks to the engine, without suffering the penalty of increased emissions.Photo Courtesy of Suzuki

If you're intending on dragracing the new Gixxer, however, be prepared to stock up on clutch plates. Our clutch went up in smoke after only three runs, and Motorcyclist's test unit suffered exactly the same fate. One of the prices we must pay, apparently, for the factory's zealous attention to shaving every possible gram of weight.

Suzuki could’ve left the GSX-R750 status quo for ’98, and still remained top dog in the three-quarter-liter class. But by fitting the new model with fuel injection and a host of other detail improvements, Suzuki has put the mark that much farther out of reach. And if you were thinking that adding EFI to the GSX-R has tacked on a much higher price tag, think again; MSRP on the 1998 GSX-R750 is $9299. What was that we were saying about having our cake and eating it too?

1998 Suzuki GSX-R750 action shot
The 1998 Suzuki GSX-R750's performance improvements continue to make the beast a class leader.Photography by Tom Riles
1998 Suzuki GSX-R750 temperature compensating system
The new GSX-R incorporates a unique temperature compensating system that uses a needle valve to adjust the cross-sectional area of the rebound damping passageway; an idea heisted from the company’s RM-series motocrossers.Sport Rider

SR Opinions
So, the question is: Is the best better? And the answer is: not really. So then the question becomes: Does it have to be? And the answer to that is: maybe not. But that leads us to yet another question which is: Is it still the best? To which I say, I guess that should have been the first question. And then I say a bunch of other stuff which is written below. The bottom line is on the bottom line.

Suzuki made two major changes to the ’98 GSX-R750—altered suspension settings and added fuel injection— electronic, that is.

If you have the buttular sensitivity of that Princess who was bothered by the pea, you will notice the difference in the suspension. The one percent of our readers who race will appreciate the changes to the suspension because they tighten everything up.

As to the EFI, the bike has more midrange, although it’s more of a product of increased torque and lowered gearing than anything else.

But the EFI has a downside too. Rolling the throttle on after having closed it completely, causes the bike to jump as if the throttle had been jabbed on hard. The new bike also has a steering damper that some found too stiff at slow speeds, but that can be fixed with a wrench and a trash can so don't worry about it. Or you could rub it in catnip and give it to your kitty-cat. Did I ever tell you about my cat named Bob? This is the bottom line. The GSX-R750 is still the rippingest.
—Peter Jones

Plenty of you out there are probably wondering what’s the big deal with fuel injection when the dyno shows it hasn’t bumped up peak power, and the midrange gains are negligible. Well, how about this: no rejetting when you slap on an aftermarket exhaust, instant power gains of around seven horsepower on top, and the ability in the future to change jetting by just plugging in a laptop and hitting a few keys? And all this for a very small increase in sticker price.

Sure, I expected more power gains from the addition of EFI to the GSX-R in stock form. But even though I was disappointed initially after reading the dyno sheets, all it took was a ride to convince me otherwise. You can’t ride a dyno sheet. And in the real world of twisty pavement, the GSX-R has the goods.

The rest of the bike may be status quo, but who said it needed changing? The GSX-R is still one of those bikes that inspires confidence. Its superb front end feedback, and tight, short chassis urge you to run it into the corners harder, brake later, and flick it in at the last possible moment. True, the motor does demand constant attention from the rider in order to get smokin' drives off the corners, but that's one of the things that makes sport riding fun—the constant challenge to improve your riding skills. So no matter how you slice it, the song remains the same: the GSX-R shreds.
—Kent Kunitsugu

1998 Suzuki GSX-R750 test
"The GSX-R is still one of those bikes that inspires confidence."Photography by Tom Riles
GSX-R Test Notes
The new GSX-R's front six-piston brakes had slightly improved power and feel over previous units. We suspect a pad compound change may be responsible.
Our red/black/silver motif test unit sported a relatively ugly-looking, flat-black painted front fender, while the blue/white models get a glossy faux carbon-fiber piece.
Suspension Settings
FRONT: preload: 5 lines showing; rebound damping: 1.25 turns out from maximum; compression damping: 1.5 turns out from maximum
REAR: preload: 42mm; rebound damping: 1 turn out from maximum; compression damping 2 turns out from maximum
Suzuki GSX-R750 Temp Gauge
High Low
Much improved midrange acceleration Still requires a skilled pilot to get the most out of it
Stiffer rebound damping improves chassis control Throttle response can be abrupt at times in slower corners
Still the class leader in outright performance
1998 Suzuki GSX-R750
The 1998 Suzuki GSX-R750.Photography by Fran Kuhn
1998 Suzuki GSX-R750 Specs
Suggested Retail Price: $9299
Type: Liquid-cooled, transverse, in-line, 4-stroke
Valve arrangement: DOHC, 4 valves/cyl.
Displacement: 749cc
Bore x stroke: 72.0 x 46.0mm
Compression ratio: 11.8:1
Carburetion: Mikuni/Denso fuel injection, 46mm throttle bodies
Transmission: 6-speed
Front suspension: 43mm inverted Showa, 4.7 in. travel; adjustments for spring preload, compression, and rebound damping
Rear suspension: One Showa damper, 5.2 in. travel; adjustments for spring preload compression, and rebound damping
Front brake: 2, six-piston calipers, 320mm discs
Rear brake: Two-piston caliper, 220mm disc
Front wheel: 3.50 x 17 in.; cast aluminum
Rear wheel: 6.00 x 17 in.; cast aluminum
Front tire: 120/70ZR17 Dunlop Sportmax D207 radial
Rear tire: 190/50ZR17 Dunlop Sportmax D207 radial
Rake/trail: 24.0 deg./3.8 in. (96mm)
Wheelbase: 55.1 in. (1400mm)
Seat height: 32.7 in. (830mm)
Fuel capacity: 4.7 gal. (18L)
Weight: 453 lbs (204 kg) wet; 425 lbs (191 kg) dry
Fuel consumption: 44 to 37 mpg, 40 mpg average
Top Speed: 162.2 mph
1/4 mile: 10.54 @ 130.98 mph

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