REALIZE A DREAM, REALIZE THE SUZUKI GSXR 750
Introducing 388 pounds of pure race-proven performance
A motorcycle has to be special - very special - to make it in the world of Endurance racing. Suzuki's Gs 1000 R did it, time and again, to earn international acclaim for its team of engineers. And these are the very same engineers we turned loose on building a street-legal version of the Gs 1000 R.
We asked for a bike that's loaded down with endurance-type features - light, fast, sure-footed, responsive. And they gave us 388 pounds of solid excitement... the all-new Suzuki Gsx R 750!
Built as a bona fide racer, this machine has actually been detuned for street use from 130 to 100 H.P. A racing motorcycle has to be stronger, more agile with better braking and handling than an ordinary street motorcycle. Its latest achievement: first-place in the famous 24-hour Bol d'Or.
The Gsx R 750's engine
The Gsx R 750's engine is a sports-rider's dream-come-true. Its specs include in-line, oil-cooled 4-cylinder with 16 valves. DOHC. TSCC and 29 mm flat-side Mikuni carburetors.
That adds up to a husky 100 HP, at 11,000 r.p.m. – and a tremendous power to weight ratio, of 1:1,76. But for competitive racing, you can buy an optional kit to retune the engine up to its full 130 H.P, and race in major competitions around the world.
The cooling system
The cooling system in the Gsx R 750 deserves a close look. Short, tightly packed (ins on cylinders and head provide some air cooling. But the primary cooling comes from 5.6 litres of oil inside the engine, circulated to crank-shaft, camshafts and rocker arms by two oil pumps.
Throttle response is heightened by a new direct air intake system and flat-valve carburetor. And a whole list of other engine components have been modified to improve performance... lighter-weight pistons, connecting rod and crankshaft for smoother, longer-life operation at high revs; a new cam chain idler sprocket to eliminate chain chatter; an extra-large 8-litre air cleaner; a lighter-weight magnesium cylinder head cover; a 4-into-1 vortex header/muffler that's thermetal-treated for lighter weight and engineered for better exhaust extraction.
And all that engine power is put smoothly into play with a 6-speed, close-ratio transmission and hydraulic clutch release. So you not only have a lot of power to play with but you have it under complete control...the mark of a thoroughbred in high-performance machines.
Check out the frame tubes
They're made with extruded aluminum - square with indented side walls - to reduce weight to 7.8 kg (18 lbs.) without sacrificing strength.
That's another idea proved out on the race tracks of the world!
A new, improved suspension
A new, improved suspension also helps the Gsx R 750 more than hold its own on highway and byway. Front-end Posi-Damp Forks respond positively to every kind of road conditions and also serve as an effective anti-dive unit.
And better-than-ever damping performance is featured in the rear Full Floater suspension, thanks to a simplified design and lighter-weight construction.
Braking is equally advanced on the Gsx R 750
Braking is equally advanced on the Gsx R 750, thanks to Suzuki's exclusive Decapiston system.
The 300 mm slotted discs on the front feature eight expanding pistons that clamp the discs from both sides -unquestionably a superior system for high-performance riding Rear braking uses two expanding pistons, with a floating disc brake caliper and torque link. Again, it's the only way to go for safe, dependable stopping.
A host of other features help the Gsx R 750 stand out from the pack
For example, night-riding holds no fears for the rider, thanks to the dual 130 mm halogen headlights.
Colour treatment is bold, dramatic, just like the bike itself. The full, streamlined fairing adds true raciness to the lines.
The slim engine design lets you bank at a surprising 55° angle. And the seat's less than 30 inches from the ground, so you really feel part of the machine.
Yes, the list goes on and on. Transistorized ignition. Foam-mounted instruments. Specially designed foot pegs. In fact, everything you learn about the Gsx R 750 says "world-class"... because everything about it comes from world-class breeding.
SUZUKI MOTORCYCLES GSX R 750
Generation 1: 1985 - 1987
Etsuo Yokouchi, probably in his sixties but as vigorous as any man in Hamamatsu,
sits down across from the Americans in an austere conference room at the
Suzuki headquarters to talk about the motorcycle
that changed the world.
A live wire of a man, his hands are always moving.
Equal parts of his lecture on the genesis of the moto Suzuki Gsx
R and lecture, is probably not the best term, sermon is more
like it have him writing furiosly on a whiteboard and sitting across the
table, teetering on the edge of his chair elbows forward, his gaze absolutely
Custom dictates orderly proceedings: ask the question, receive
an answer. At the beginning of the interview Mr. Yokouchi sits down-barely-hands
folded on a large envelope containing rare photos
of the periods, and says, "Shall we begin?" But before the translator
can form the first syllable of the first question, Mr. Yokouchi is up
at the whiteboard, scratching out graphs and specifications, comparing
weights and horsepower outputs of bikes before the Gsxr.
He speaks forcefully about a story now twenty yers old, a tale he has
told probably a thousand times.
Hi demeanor, his sheer enthusiasm make
it seem like the first recitation a story offered as though you were the
first person kind (or perceptive) enough to ask. And he is clearly delighted
to be telling it.
Inside of five minutes, you understand the nature of the man, his conviction
and drive. You imagine the intense experience of the junior engineers
over the years who have had to work under his exquisite dynamism. (Others
later recall his passion, commenting that he has, unbelievably, mellowed
withage.) He locks eyes on yours, crow's feet visible through his larged
glasses, until you have convinced him you understand every detail of the
poiny he has just made.
Nodding will not do. Hai (an emphatic "yes"
in Japanese) will not do. He forces you to respond, to repeat the lesson
like a first-year chemistry student. His approbation feels like a gift.
You have you lucky soul, just met the feather of the Suzuki Gsx
Mr. Yokouchi's place in history is secure, thanks to the Gsxr.
Unusual for someone in a position of power in a Japanese company, he has
an outspoken proponent of pushinh the technology to improve the breed.
Many have misunderstood the apparent lack of passion in japanese engineers
(something Mr. Yokouchi neverworried about).
For one thing, it's cultural;
to stand proud of the company and accept credit for accomplishments
can be seen as disrespectful to the rest of the team. Moreover, the culture
is deeply ingrained with the concept of continual improvement. To great
degree, the people, and ven company, are the secondary importance to the
In late 1981 and early 1982, racing was on Mr. Yokouchi's mind; it was
an endeavor ha viewed as the ultimate test. "Racing is love",
he says, meaning that it takes you to extremes.
If a machine is to be
competitive, it must be a better performer;
there are no market surveys at the checkered flag, no success come from
playing it safe.
Racing machines must be powerful, of course, but it is
equally important that they be light and nimble. With this idea percolating
in his head, Mr. Yokouchi surveyed the sportbike landscape of the late
1970s and early 1980s and plotted his course.
We look at that period from modern times and see the goal the Suzuki
Gsxr represented as such a clear target- reduce the weight,
and even if you don't dramatically increase horsepower, performance will
It helps to understand motorcycling in that period to fully
appreciate the impact of the first Suzuki Gsxr.
In the years closing out the 1970s, most sportbikes were simple derivatives
of so called standard bikes. From Japan, they were almost universally
inline four-cylinder, air-cooled engined strapped to simple, round-steel-tube,
This was so much the orthodoxy that a term emerged:
UJM. Universal japanese motorcycle. Despite the jingoistic
ring, it was not used specifically as a damming term except by those with
allegiance to other brands or continents.
From two-stroke to four stroke, a technology race against time
In fact, UJM came to mean universally
good, if conservative, engineering. The bikes all started on the first
try, didn't leak oil, and were typically well enough developed that they
didn't shake themselves apart.
The japanese companies had many of the same
resource available, and their engineers had followed many of the same
paths, resultings in their bikes looking and working much alike. There
was also, undeniably, some copyng, the inevitable "hey, that's a
good idea... should have thought of that".
also was a period of transition from two-stroke to four-stroke power plants,
honda unquestionably landed the first punch with the CB750 in 1969.It
reset the standars of fit and finish, durability, and broad appeal even
if it was a conservative choice.
Enthusiast were lining up for crazy-fast
bikes- the air cooled GT380 and GT500, and the liquid-coold GT750, were
genuinely middle-of-the road models.
They were two-stroke versions of
the CB750 in many respects. By the late 1970s, regulations were making
the two-strokes harder to get into certain markets that had set more rigorous
emissions and noise standards.As a result, the push was on the develop
four-stroke alternatives. For the most part, the other manufacturers took
turns stealing the limelight from one another. In 1973 Kawasaki's 900cc
Z-1 cemented the firm's reputation for building lightning-quick bikes.
Honda joined with more twin-cam engines.
Yamaha, still trying hard with
two-strokes, nonetheless developed its own line of four-stroke bikes.
Slightly late to the party after playing with rotary engines in tha RE-5
and thoroughly refining two-cycle power plants, Suzuki moto
introduced its first modern
four-strokes in 1976. The GS 750 four and the Gs
400 parallel twin were the company's first toes in the weather
of the modern era.
Soon, a Gs 550 arrived. And by 1978,
the company had introduced the mighty Gs 1000.
For ' 79, Suzuki moto brought out seminal Gs
1000 S, a bike built as a replica of sorts for the machines beings
campaigned in Superbike racing at that time. This could also be seen as
the first step toward individual sport and standard models. That is, motorcycles
with clearly different intent lower handlebars and small, wind splitting
fairings for the sport models; taller bars and no fairing for the standard
models; and shaft drive with a detuned engine (for more torque). for the
touring riders. The year 1979 also brought the first L model, a cruiser-like
motorcycle that was little more than a cosmetic alteration
of a standard model, and the G model, a shaft-drive version of (again)
a standard model with a slightly deeper
seat and taller handlebars (but still no standard fairing).
company was relatively new to building four-stroke, Suzuki moto
learned quickly and developed the line with astounding rapidity. Scan
the brochure from the period and you'll notice something else: Suzuki's
line grew fast in terms of the number of unique models.
This was the result
of what had become known as the Honda-Yamaha war.
In the late 1970s and
early 1980s, Yamaha market share had grown rapidly and was quickly encroaching
on the perennial leader, Honda. seeing victory within their grasp, Yamaha's
managers and engineers began an all-out assault on Honda's position, building
many new models, investing in technology and production equipment, and
generally just ramping up as though for war.
In that period, as today,
Honda was much bigger than yamaha and could increase its efforts without
breaking the bank.
For companies with fewer resources than Honda and Yamaha, these were trying
times. "the Honda-Yamaha war hurt us all", says Masami Hga,
general manager of the motorcycle planning departmant.
"we were forced to keep up with the new models and the advanced technology.
We were carried along in the war and had difficulty surviving in it.
the war ended with Yamaha calling a truce, but not until every manufacturer
had been stretched to the limit developing and producing a tremendous
number of models. The result was an oversupply of products placed into
a softening economy. No motorcycle dealer in the U.S.
at the time was particulary happy.
Even in these tough times, Suzuki moto continued to innovate.
The company's other milestone of the period, beyond the Gsxr,
was the Hans Muth designed Katana, another model spearheaded by Mr. Yokouchi.
although its underpinnings were utterly convetional, using the air-cooled,
four valve per cylinder engine from the Gs 1100 (altered to 1000 cc for
the U.S. market with race homologation in mind) and ordinary frame, its
radical styling elicited gasps of surprise from the press and enthusiasts
alike. Suzuki's styling designers attempted to leverage
the Katana's unusual profile into restyling jobs for other models- the
Gs 1100 E, Gs 550 Katana, Gs
650 Katana, and Xn 85 Turbo.
the early 1980s, the fashion of making sportbike separate from standards,
custums, and touring righs had fully taken hold. The engines were becoming
incrementally more refined, and the chassis were starting to move toward
race-like architecture, using box-section steel tubing on some models.
Swingarms that had been around steel tube became gusseted steel and the
Suspension sophistication improved dramatically, as did tire
construction and grip. The sport sector began to gain in sales, and the
manufacturers quickly realized that successful sportbike-particularly
one the raced succesfully-could benefit the entire line through racing
the brand image. In 1983, Honda introduced the VF750 interceptor, also called V45, as in
45 cibes inches.
was, at time, the most advanced sportbike made, and it was a model that
had no direct standard-category sibling. (The VF750 Sabre, introduced
a year earlier, was far removed from the V45.) This is an important distinction.
Before, all manufacturers built sport models from the bones of the standard
bikes. The racer version might have a bit more power, an additional brake,
possibly a lower handlebar and further rearset footpegs. Honda drove the
separation of sport and standard models by allowing little of the Sabre's
DNA to dilute the interceptor's pure-sport genetics.
The interceptor was fast and handled well but was heavier than the inline-four
models it replaced.
It won lots of races and more than a few awards. Cycle
Guide magazine named it Motorcycle of the year and chromed
one to put on the cover. (The particular bike was actually a nonrunning
early prototype). At
the time, the motorcycle press openly speculated that
the future of sportbiking would folow the interceptor lead without question:
the bikes would become ever more sophisticated and feature driven, with
the lure of new configurations particulary the V-4 counting for a lot
when it came to attracting customers. The same was happening over Kawasaki,
as its GPz series grew in performance and weight. Even
the Ninja 900R, when it appeared in 1984, was a heavy motorcycle
whose powerful engine largely overcame the fact that the steel-tube chassis
wasn't quite as competent as the Honda's.
Still following the traditional routes in the early 1980s, Suzuki
moto was producing new versions of its main models, introducing
air cooled engines that were far more modern and compact than the old
(but still popular) two-and four-valves engines. (the roller-bearing-crank
Gs1100 engine, as locomotive-like and loved as it was, nevertheless was
a massive, heavy power plant.)
It was a matter of timing. Suzuki moto elected to take
a conservative approach to the sporting philosophy, choosing to develop
a bike with good sporting credential that was also reasonably comfortable
and flexible. Honda and Kawasaki went the other way, producing ever more
serius-minded sportbikes, with Yamaha not far behind. History shows that
the interim motorcycles weren't a great success, even
as the air-cooled Gs 1150 forged on, still selling reasonably well. (that's
a relative term. By 1984 and 1985, motorcycle
sales were hurting in the U.S).
Still, in the early 1980's even as sportbike technology seemed to accelerated,
in truth the models from every manufactured progressed gradually in terms
of technology and performance. As they took small steps up in many categories
at the same time-engine power, chassis rigidity, braking performance they
also put on weight. Honda's interceptor weighed more than 500 pounds dry,
and the air cooled Kawasaki Gpz 750 was just a few pounds lighter.
Meanwhile, back in Mr. Yokouchi's lair in 1983, domestic market custumers
caught a glimpse of Suzuki's technology to come in the
RG 250 Gamma. It was light, very light, but you'd expect that of a two
The arrival of the GSX R 400, a step towards the GSX R 750
Next, in 1984, came the Gsxr 400. Think of it
as the trial ballon, a relatively low risk peek at what could be done.
The engine, a liquid cooled inline four, was placed into an all aluminium
frame. as result of the frame and abnormal obsession with detail weight
reduction, the little bike came in 18 percent lighther than its japanese
market competition. It was heralded as one of the best sportbike of the
time. No doubt the other three of the Big Four were eyeing the new think motorcycle with concern. Even if they took it seriously
right from the start, they would begin a retaliation already behind schedule.
"I felt that if we could do a 400cc bike that was 18 percents lighter,
we should be able to do the same with a 750", recalls Mr. Yokouchi.
It was an audacious assumption: as engineers will tell you, scaling effects
are hard to predict. The critical task would be to keep everything in
balance, to make every part as light as possible.
"I knew that lights was right direction", he says "we had
a voluntary 100PS (the metric equivalent of 98.6 hp) limit. We were getting
close to having 100 PS already, so the only avenue open for better performance
was to reduce weight". Mr. yokouchi pushed his team relentlessly. "I asked the engineering
team to bring in a Gs 750 E4 (the 1984 air cooled Gs 750 E in the U.S.
market) and take it completely apart. I had them paint components that
we had no trouble with no breakage or durability issues in blue. I had
them paint parts that had broken in the field in red. When we brought
all the parts together, they were almost all blue! We were building the
bike too well; noting ever broke. As an engineer, I
say this is wasteful. We have become too conservative".
is corroborated by Hinori Iguchi, the engineer in charge of all the engine's
moving parts during Gsxr development: "we were
building very conservative engines at the time Nothing broke". Emboldened,
Mr. Yokouchi set the goal: 100PS from a 750cc engine and 20 percent less
weight than the bikes of the day, which were all around 480 pounds (220
Thus, the target was 379 pounds (176 Kg). The race was on. Chassis
development took place simultaneously with engine development, with each
department charged to reduce weight wherever possible. And if such weight
saving measures called for unusual or expensive materials, new
technologies would be developed to produce them economically. Suzuki
moto was a small company at the time and simply could not afford
to produce a motorcycle at a loss, no matter how important
it might be to the long term health of the company.
Mr. Yokouchi was convinced that race bike dimension would translate to
the street. "The motorcycle doesn't know where it
is being ridden", he says. In other words, good handling on the track
would make for good handling on the street. (In retrospect, Mr. Yokouchi
and his team overstepped this idea ever so slightly, as a lengthening
of the wheelbase for the 1986 model attested.
Still, you have to admire
his clarity of vision and willingness to says the course.)
moto had campaigned and won on the Gs 1000 R endurance racer. It had won the Suzuka 8 Hour with riders Herve Moineau
and Richard hubin en route to winning the 1983 Endurance World Championship
for the HB Suzuki moto team. Although its Gs
1000 derived engine was primarily air cooled, it did employ a
version of oil jets aimed at the undersides of the pistons, as used on
the production XN 85 Turbo.
The chassis was forward looking.
It used a short wheelbase, tight rake, comparatively little trail, 18
inch slicks, and, most important, an aluminium tube construction that
foretold the development of the Suzuki Gsxr. These tubes
were a combination of rectangular and round stock welded together in true
one-off fashion. But while the material was new, the overall concept was
not. The frame formed a convetional double cradle, with massive main struts
leading back from the steering head toward a point just aft and above
the carburetors. This part of the frame then turned down to meet the swingarm
pivot section from below. The upper tubes were moved outboard from the
convetional location steel tube frames
of this period had their main member or members close to the centerline
of the bikes, with the horseshoe-shaped lower part of the fuel tank draping
over. Widening the upper frame members increased rigidity without having
a big impact on weight, but new ways of manufacturing and mouting fuel
tanks had to be considered. Plus, room for a large airbox behind the bulky
engine had to be in the plan as well. Little did competition or race fans
appreciate that they were seeing a configuration that would become synonymous
with sportbike performance. And while a great deal of the Gs 1000
R'success can be laid at the feet of its stout engine and well
organized team, the low weight afforded by the alloy frame should not
A lighter bike is easier on its tires and on the rider,
which is of particularly high importance in endurance racing."It
was an amazing time", says Akimasa hatanaka, part of the Suzuki
Gsxr chassis design team. "We had a lot of heated discussion.
How should we weld the frame? What materials are best? In a lot of ways,
we were groping in the dark. But we had the racing experience to lead
us. We Knew that following what worked in racing would help". The
team did more than just folow; they quite faithfully reproduced the Gs
1000 R in the new Suzuki Gsxr. Rake was dramatically
steep 26 degrees, trail was 4.2 inches, and the wheelbase was a terrifically
short 56.1 inches.
Put in perspective, Honda's V45 Interceptor had a rake
of 28.2 degrees, 3.8 inches of trail (not an Unusually small number, thanks
to the 16 inches front wheel), and a wheelbase of 58.9 inches. The Gsx
R's dimensions weren't just smaller than others' they were tiny. Suzuki had made other aluminium frame street bikes before
the Gsxr 400 and the RG 250 Gamma two
stroke and had worked hard to hone the material into something that could
be produced within costs and time guidelines. With these requirements
in mind Mr. Yokouchi's team had elected to make the frame from combination
of material. The headstock and swingarm pivot area are both area castings
Aluminium castings can take fairly complicated shapes easly and, if made
properly, require a minimun of machining and preparation before assembly.
Between the cast pieces were extruded aluminium, box section tubes. Where
the tubing runs are relatively straight and uncomplicated, extrusions
offer a high strength to weight ratio; the key is to use each material
where it is best. Moreover, Suzuki moto had developed
an aluminium alloy that did not need to be heat treated after welding,
which saved production cost. Advances in materials also led Suzuki
moto to use Lightweight cast wheels.
Mr. Iguchi recalls: "We built a boldly lightweight frame. We were
pushing ourselves very hard".
With the Gsxr, Suzuki moto showed its
willingness to reinvent even propietary technologies in the pursuit of
reduced weight. An example is the Gsxr's Full Floater
rear suspension. Previous examples of the system for street bikes used
a pair of vertical struts rising from the swingarm that connected to a
rocker arm. The fulcrum of the rocker arm bolted to the frame, while the
free end compressed the top of the shock. The bottom of the shock was
connected directly to the swingarm.
But with the Gsxr, Suzuki moto recast
the idea, solidly mounting the top of the shock to the frame. Below the
swingarm is a banana shaped linkage housing an eccentric cam that, along
with the natural changes in the linkage ratio through suspension travel,
made the system fairly progressive.
The reason for the change? Weight, for one, but it also lowered the overall
center of gravity. Mr. Yokouchi anticipated that his new engine design
might be more top heavy than the previous generation's power plant, and
he wanted to compesate. Moreover, the simplified system created room for
the battery and electrical components.
The fork was also comparatively beefy. The Showa unit had 41mm tubes,
where the de facto industry standard was a 39mm unit. A fad of the time
was some form of anti dive damping; the Suzuki moto had
a simple rate sensitive mechanism on the leading edge of the fork leg.
This system did not reduce braking feel, and a similar one, electrically
activated by the brake light circuit, would later be used on the Gsx
Eighteen inch wheels were fitted front and rear and given either Bridgestone
or Dunlop radial tires. The size 110/80VR18 front and 140/70VR18 rear
seem impossibly small by today's standard, but they were cutting edge
stuff in 1985. Many have asked Suzuki moto did not use
the then popular 16 inch front wheel on the Gsxr. There
are three answer: One, the 18 incher followed the Gs 1000 R race bike pattern. Two, the bike was expected to be very light and therefore
maneuverable. The lighter steering respose of the 16 inch tires was not
necessary. Third, the taller tired permitted slightly larger brakes and
rotors than would be possible on a 16.
This groundbreaking chassis would carry an equally graoundbreaking engine. Suzuki had done V-4 engines in the Cavalcade touring
bike and the Madura cruisers, but such a layout wasn't even considered
for the Suzuki Gsxr. Market research and basic packaging
demands pointed to the inline-four.
Gsx R 750 and oil cooling, the goal of 100 hp
The turning point for the Gsxr project actually took
place two years earlier, as Mr. Yokouchi and his engineering staff were
trying to lower temperatures in the XN85, Suzuki's sole
turbocharged motorcycle. The two valve, air cooled 650
engine was having trouble staying together under the kind of turbo boost
that would create reasonable power. Mr Yokouchi looked toaircraft engines
for a solution. Many of the large piston engines developed during World
War II relied upon a generous amount of oil used for cooling; many radial
engine aircraft had dipsticks calibrated by the gallon rather than by
the quart. Many used oil squirted at the pistons from underneath to remove
some of the combustion heat. When the piston are large, as they were in
these massive radials, heat conduction to the bore is a problem. In addition,
these engines were turbocharged andran on a tremendous amount of boost,
further raising combustion pressures and temperatures.
The oil effectively improved the life of the engine and, in turn, allowed
them to make more power with out additional displacement.
Mr. Yokouchi turned to oil jets for the XN 85, and they
worked. File that away for future reference. At the times of the Gsx
R's development, it was assumed that air cooling alone wouldn't
do the job. Already the company had trouble tuning the air cooled engines
for maximun power without overheating. Compromises in valve timing and
compression ratio eased the work of the air cooled engines but clearly
were not going to hack it when 100PS from 750cc was the
Contemporany casting techniques prevented switching to liquid cooling
while still maintaining the low calorie diet. So the idea of making oil
do more work was floated. This is the original story that has been circulated
for the past twenty years, the linchpin to the Gsxr's
success. Hemmed in on one side by the desire for horsepower that an air
cooled engine could not generate reliably and on the other side by production
limitations that would have forced extra weight on the machine, Mr. Yokouchi
kept thinking. In fact, he had three rules for his engineers (four if
you count never sleeping): One, don't copy. Do your own thing; forget
whta the competition is doing. Two, go for new technology. It might be
harder in the beginning, but it pays off very quickly. Three, avoid conventional
wisdom. The last is probably the most persuasive. After all, the conventional
wisdom of the days was that you could not building a durable, street legal
bike the weight of the Suzuki Gsxr.
Oil would carry the load, so to speak. And while most refer to the Gsx
R engine as being oil cooled, it's worth remembering that it's
still largely air cooled. Think of the oil system as a necessary supplement,
a way of getting heat out of places that vexed air cooled engine's designers,
namely, the top of the combustion chamber. Not wanting to deprive the
engine of oil for lubricating purposes, a double chamber pump was designed.
The high pressure side fed the bearings and the piston squirt jets; a
low pressure (and therefore high volume) side fed cooling circuit. The
engine oil was, obviously, shared between these two circuits. Just to hedge
bets, the engine carried 5,3 quarts (5 liters) of oil in a wet sump.
It was also assumed that the new engine would have four valves per cylinder.
It was the new standard exceping Yamaha's insistence on five per jug,
a technology that debuted the same years as the Gsxr and the right way to go for the power goals. But air cooled engines need
as much finning around the spark plug and valves as possible; the more
valves, the less area for such finning.
The solution was to completely rethink cylinder head architecture. Instead
of having multiple fins across the top of the head was cast as a flat
plate with tall tunnels for the spark plugs. The valvetrain resided in
a large aluminium valley, topped by a wide magnesium cover with thin,
short fins. External oil lines came up the back of the cylinder block
and fed spigots that shot a great volume of oil into the valvetrain cavity.
But it wasn't just a matter of filling the top of the head with oil and
hoping for the best. Mr. Yokouchi explains how he arrived at that Eureka!
moment that brought him to next leap.
"It was a lazy boy... it's true. In my home, we had a cast iron bath
heated by a wood fire underneath. My grandmother would tell me to continue
to stir the water in the bath while it heated. well, i was lazy, as I
said, and didn't do that. I don't remember what i was doing, but i didn't
think stirring the bath was important. But, over time, I realized that
doing it my way took one or two extra piece of wood to get the bath hot.
I was amazed that my grandmother was right but, many years later, grateful
because she gave me the key (to the Gsxr's cooling system).
It was boundary layer!
Central to this design's success was his realization that a fluid flowing
past a fixed object breaks into zones of flow. The flow nearest the object
in this case the cylinder head tends to slow in what is called a boundary
layer. As it slows, the rate of heat conduction is reduced. This could
not be allowed. Oil by itself is approximately 10 percent less effective
than water at picking up heat; it could not be left to languish.
Recalling his boyhood lesson, Mr. Yokouchi decided that the oil around
the combustion chambers had to be kept moving to break up the boundary
layer, therefore improving heat conduction. To that end, small baffle
plates were installed adjacent to the spark plug tunnels. These kept the
oil moving briskly past the hottest part of the head for maximun heat
So far so good. Lots of oil is in there, and it's routed to best effect.
Now what do you do with it? It seemed straightforward to let the oil drop
down the central cam chain tunnel to the sump, but that was tested and
found to be insufficient. Windage losses from the oil striking the cam
chain in the tunnel were one thing, but the oil foamed as well. (Common
oil wasn't as good as it is now).
Chiaki Hirata, one of the Gsxr engineering staff, remembers:
"we continued to develop the oil cooling system but found that at
high rpm we lost oil pressure. We had used colored water to trace the
flow of the oil, but then discovered that the oil falling down the cam
chain tunnel was foaming badly. Eventually, the oil pump could not take
up the oil, and the pressure dropped".
Another creative solution: a pair of drain back tubes were fitted to the
front of the head, leading down to the sump. This cured the foaming problem,
but Mr. Yokouchi had to prove that the flow worked. His test was disarmingly
simple. He used one of the prototype engines with a cutaway cam cover.
By means of common water hose, he showed that the drainbck tubes could
handle a great deal of volume without backing up. "I remember standing
outside the engineering office, showing the staff how it worked. We must
have looked crazy, standing there getting our pants wet, " Mr. Yokouchi
With the cooling medium decided upon, the team continued to work to get
the power and to trim weight.
Power, weight and safety of the Gsx R 750
"We were told to make it as light as
possible", says Mr. Iguchi. "We were told to go ahead and hit
the wall' and try to break the engine.
Before that, the engine was made
as solid and durable as possible it didn't break very much and the instruction
was to go ahead and break it. We had very aggressive design schemes, so
it broke very often".
Every component was scrutinized. Pistons, connecting rods, main bearings,
crank all came in for steely eyed weight control. All were smaller in
some cases much smaller than on the previous 750. Smaller bearing have
less friction. According to a preview report in "Cycle World"
in 1985, the diminuitive bearings were responsible for a 3 hp savings
at 11,000 rpm. Continue this kind of efficiency-seeking throughout the
engines, and horsepower will come.
Of course, the traditional ways to acquire power also worked. The Gsx
R engine had large valves, aggressive cams, large carburetors,
and a free flowing four into one exhaust system tuned to be benefit high
rpm power. Oil cooling allowed for thin stemmed valves with big heads,
which were lighther yet flowed more. Light valves also tolerate aggressive
cam timing and lots of lift.
Packaging played a role, too. The cylinder
pitch was made as narrow as the engineers dared, given that the barrels
were still air cooled. Fine pitch finning was used on the head and block
to facilitate cooling. Such finning increases the cooling area without
dramatically increasing weight. This was another idea that Mr. Yokouchi
borrowed from aircraft technology, but not before he had to convince the
production department to improve the company's casting abilities so they
could actually make the parts.
With the bores packed closer together, the bottom end was becoming narrower,
but the placement of the alternator behind the cylinder bank was the next
logical step. Other manufacturers had done this, mainly to get the alternator
off the end of the crank as Suzuki moto had done. The
main benefit to a narrow engine is that it can slide down and forward
in the frame without affecting cornering clearance. Look at a photo of
the early 1000cc Superbikes and you'll see replacement
engine covers cut at an angle to get any amount of precious clearance.
It was all coming together. "In early testing, I asked the riders and
engineers to try their best to break the bike," recalls Mr. Yokouchi.
"I wanted to find the weak spot. When we did find something, I had to
convince them to fix only what broke. The feeling at the time was that
nothing should break, so the natural reaction was to make everything heavier.
But the bike has to flex if you want to keep it light." Later, Mr. Yokouchi
admitted to an American journalist that he was circumventing the normal
development process, in which the race bike was derived from the street
bike. "We were develop ing a race bike," Mr. Yokouchi said. "We had to
pretend that we were making a street bike. At the end of development,
we had a race bike and then had to make minimal changes to prepare it
for the street." Pretend.No doubt if anyone could "pretend" to Suzuki
moto management and get away with it, it was Mr. Yokouchi. In
the styling design department, there was no pretending.
Gsx R 750, innovative styling derived from the R 1000 GS racing
"There are many
approaches to styling, but this is a racer replica," says Tetsumi Ishii,
styling designer of the Gsxr. (In Suzuki parlance, a styling designer is responsible for the shapes and colors
of the bike but is, by and large, subservient to the engineering group.It's
his job to make good looking what the engineers have determined is the
right way to make the bike.) "What is most important is to keep the feeling
of a racer replica," Mr. Ishii says. "I learned a lot from this project.
The fairing comes from the Gs 1000 Rrace bike as closely
as we could. We wanted the racer look. We spent some time in the wind
tunnel to determine the best shape. For example, the small wings on the
fairing came directly from the Gs 1000 R, as did the bubble windscreen."
The Gsxr's distinctive two light face was dictated by
regulation as much as by styling.
"At the time, it was required that we
place the headlight face at or behind the front axle," Mr. Ishii recalls.
"This is why the Gsxr has this kind of face. We wanted
to maintain the endurance racer look but had to find just the right headlight
to do the job and still be street legal.We could not use a single light,
as on the racer, also because of the rules." Other aspects of the bike's
styling resulted from more mundane concerns."The side panel [beneath the
seat] is large because we wanted to cover the pipe hanger," Mr. Ishii
says. "On the Gs 1000 R, this was exposed, but we couldn't
allow it to get in the way of the rider's feet on the Gsxr."
Also of note are the Gsxr's distinctive bullet shaped
mirrors. "We tried several designs," says Mr. Ishii. "But we came to the
bullet mirrors because they worked well in the windtunnel and were appropriate
for the bike's look." Some other detailing that was picked up right from
the race bike: the small vapor reservoir and external vent hose on the
fuel tank, as well as the flush filler cap. In a period of design when
such appurtenances would have been considered vulgar on a street bike,
they were instead noticed and appreciated by enthusiasts who really wanted
a "race bike with lights." Cementing the impression was a masterstroke
of design: the race inspired instrument panel.
A trio of gauges, surrounded in foam, reflected back the same image every
racing enthusiast saw when peeking over the velvet rope in the pits of
a G P race. The tachometer didn't even register below 3,000 rpm, just
like the Gs 1000 R. Today we might consider this an affectation,
but it was meant to convey the spirit of the endeavorto replicate, as
much as possible, the race bike. Development continued at what seems,
even today, like a breakneck pace. And then it was ready.
The presentation of the GSX R 750
Suzuki moto showed the Gsxr 750 to a stunned crowd
at the 1984 Cologne show, promising production for the 1985 model year.
You can imagine: the carpet around the display was worn to threads. Immediately,
European and domestic press were lauding Suzuki's motorcycles courage in producing a full on race bike for the streets.
waited as patiently as they could. And those who said, "Great, a racer
for the street. It won't make a good street bike," would in many ways
be proven right. But they were also to be roundly ignored by a suddenly
large and vocal subset of hardcore enthusiasts for whom this was the perfect motorcycle. In March 1985, Cycle magazine said, presciently,
"Sportbikes will soon be divided into two categories: before the Gsx
R, and after." In the May 1985 issue of Cycle, Kevin Cameron
wrote: "What Suzuki has done with every part of this
machine is what has had to be done with every part of GP and endurance
racing machines several times a year, and the technique works; detailed
design with critical thought to preserve or enhance function while simplifying
and adding lightness.
Suzuki moto has done more even
than that the company has brought this kind of reasoned design to the
marketplace at a competitive price. And that is the best integration of
design and manufacturing technology seen so far."
For the April 1985 issue
of Motorcyclist, Jeff Karr, who attended the world press launch in Japan,
reported: "The Gsxr 750 put on an impressive show [at]
Ryuyo. When recently shod and ridden well, it's a tremendously fast race
bike, which should make it a wickedly fast bike on a racetrack like road.
Its cafe racer riding position will hurt it on tight roads, but the tremendous
motor will let it make up a lot of ground."
In concluding the story, he
said, "The 750 class has gone from stale to startling
this season. For now we Americans will have to be content with the [Yamaha]
Next fall the Suzuki Gsxr 750 will arrive on
our shores and the sporting motorcyclist will be confronted with one of
the most pleasantly difficult decisions in memory." Comments in the American
press mirrored those in Europe and Canada where the Gsxr was a smash hit, as everyone had hoped.
But the bike was not brought into
the U.S. until 1986. Why? "We had a production limit," says Takeshi Hayasaki,
group leader of the planning group for overseas marketing. "And the American
market was very different, less into sport riding than in Europe.American Suzuki moto was concerned that they would not have as
much success with the bike." On the other side of the ocean, American Suzuki's motorcycles Mel Harris explains:
"In 1985 they were not sold in the U.S.
That became a sore spot for our
dealers, but also that time was turbulent in the industry and we had
Part of the reason the bike didn't come here was the
ITC tariff on bikes 700cc and above. We had to pay the tariff in 1986,
but it wasn't as high as it would have been in 1985.
The retail price
with the tariff would have been too high."
The so called ITC tariff imposed by the International Trade Commission placed a steep financial burden
on imported motor cycles of greater than 700cc. Japanese manufacturers
were allowed to bring in 6,000 bikes per year on a quota system without
the tariff. But the new tariff, signed into law in 1983 by President Ronald
Reagan, imposed stiff sanctions on bikes 700cc and larger.
The first year
into law, the tariff was a staggering 49.4 percent in subsequent years,
the tariff would be reduced to 39.4 percent, 24.4 per cent, 19.4 percent,
and 14.4 percent, respectively. For most of the manufacturers, this rule
required expensive changes to the existing 750 class
machinery so they would fit under the 700cc rule.
Suzuki moto reduced the GS 750's displacement to 699cc, but never
tampered with the Gsxr. The belief was that its top
line sportbike should not be emasculated and that, when finally introduced
in 1986, the 24.4 percent tariff would be slightly more tolerable than
the 39.4 percent tariff of the year before. So the Gsxr except for those bikes brought in through Canada didn't grace American
roads until 1986. By then, Suzuki moto had reacted to
complaints of a slight lack of stability from European riders and extended
the Gsxr's swingarm by a full inch.
"In the second year, when we rolled them out, I think there was a lot
of apprehension on everybody's part with the insurance. We were disappointed
because we thought it would be a huge sales success. But it actually started
slowly. At the end of the year we were wondering what we had to do. That's
when we developed the Gsxr Cup, which ran out in Riverside,
California, for the first time. At about that time late in the season
it really kicked in. People realized we had a real race replica. They
saw that it was everything you wanted to have if you were a motorcycle enthusiast. It took off."
The Gsxr Cup was a one make
national racing series built to encourage privateers' involvement.It has
since evolved to include the popular SV 650 model as
well. Early on, there were suggestions that a bike so light could not
be durable. Aiming to test the theory, Cycle World conducted a twenty
four hour endurance test. It took place at Uniroyal's massive five mile
long circular track that would allow the Gsxr to run
flat out for as long as it could. "We wanted to see just how good the Gsxr was," recalls Paul Dean, then editor of CWand now
"And we wanted to do the test with a stock bike."
(The previous record was held by a modified motorcycle.)
"We sent David Edwards [then feature editor and now editor in chief of
Cycle World] to the Suzuki moto factory, where he randomly
picked two bikes off the assembly line and then sealed the engines with
wire and a tamper proof seal. I had met with American Suzuki moto president Mr. Shigenoya, and he liked the idea. He claimed that durability
of the bike would not be a concern. 'We have already run the engine at
its power peak for twenty four hours on the dyno,' he told me." In the
end, despite problems with tires chunking a malady that Dean says he later
discovered to be the result of replacement tires being put on the track
without any heat cycling; the "green" tires just didn't make it the team
got its record. The quicker of the two bikes averaged 128.303 mph for
the twenty four hours, beating the old record by more than 10 mph. Other
magazines decided to test the Gsxr's mettle on the track.
In a 1986 racetrack comparison by Cycle Guide magazine, Wes Cooley and
Kenny Roberts rode the Gsxr 750 and the Yamaha FZ 750
against their old race bikes to illustrate how close each new production motorcycle had come to real race technology. They discovered
that the gap from racetrack to street had closed dramatically from where
it had been just a few years before. The article's author, Jerry Smith,
concluded, "Based on what we learned at willow Springs, the blurring of
the distinction between street bikes and race bikes is anything but sales
hype .... For the next generation of high performance street bikes, the
jump from the racetrack to the street might be so short that you'll be
able to smell the hot oil and hear the fans cheer every time you push
the starter button."
Final touches to the GSX R 750 and the arrival of the Gsx R 1100
For the first generation of Gsxr's, Suzuki's motorcycles engineering staff barely had time to draw a breath.
The Gsxr 1100 was ready for 1986, based strongly on
the 750 but significantly altered for the crankshaft
horsepower. It was scarcely heavier than the 750 and,
as a result, a featherweight compared to the liter bikes in the class.
To bolster its racing efforts, in 1986 Suzuki also produced
a special limited edition of the Gsxr 750 that sported
larger brakes, a dry clutch, solo seating, and a host of other small changes.
As expected, the race bike ambitions of the Gsxr 750 were played out for real. Remembers Yoshimura's Don Sakakura: "Back then,
Superbike racing was based off a production bike. Suzuki moto would supply us with production motorcycles in the crate.
Gsxr 750 1985
They'd require extensive modifying of the chassis and the suspension,
including strengthening of the chassis. Switching to the 750E4 [the Gsx
R's predecessor], it was a lot easier. They were more designed
for performance.The chassis didn't need all the modifications and gusseting
the Gs 1000 S did. We still had to develop our own camshafts,
and we worked with Mikuni back then to develop the VM series of carburetors
for racing. But the GS 750 was a lot easier to work with,
from a racing standpoint, than the Gs 1000." Everything
changed when the Gsxr 750 finally arrived for stateside
racing in 1986. Mr. Sakakura says: "With the Gsxr, we
got the aluminum chassis and the engine performance; from that point it
made our job that much easier. We didn't have to go all through it, strengthening
the frame. It worked really well as a production bike for the track. Most
of what we did was to make changes to make the rider comfortable rather
than wholesale changes in the engine and chassis. It was just a very balanced
package that worked well everywhere. The engine we continued to develop,
but the chassis we left alone. It was a huge advantage."
And so it continued. While the Gsxr did not come to
dominate AMA Superbike racing against the better funded factory teams
from Honda and Kawasaki, it was a complete and total sales success. Though
few fully understood the impact of the Gsxr in the mid
1980s, it's clear in retrospect that it turned an industry on its ear.
Says Masaaki Kato, president of American Suzuki moto,
"The Gsxr put Suzuki moto on the map."