A Decade of the GSX-R750

In an arena when updates or indeed model lives are seemingly measured in months,
believe it or not, up until 1995 Suzuki produced its eleventh GSX-R750. In that
regard, the marque's 750cc sportsbike is in a class of its own - it's uncommon
for a touring bike to boast such a history, let alone a cutting-edge sportster.
Here's how the bike's evolved.

 
1985
The very first mass-produced repli-racer (the GSXR750F) was released to an eager
public on June 3, it was an immediate success.
The bike was based closely on the factory's Formula One racer, and claimed an
impressive 100bhp at 10,500rpm, with a featherweight 176kg to propel. The
oil-cooled powerplant sported cylinder dimensions of 70.0 x 48.7mm - the
dimensions the first water-cooled GSXR, the WN, returned to in 1992.
The original GSXR had 29mm flatslide carbs, an alloy double-cradle perimeter
frame, 18-inch wheels with 110/80 and 140/70 tyres, and proved its racetrack
heritage with a debut win in that year's Adelaide three-hour production race
with Mick Hone Suzuki rider Rob Phillis aboard.
The GSXR750G remained virtually unchanged from the F. The GSXR750 was joined in 1986 by its new 130bhp GSXR1100 big brother, and also the Limited Edition GSXR750 with dry clutch altered cosmetics and longer swingarm. The latter was primarily a racetrack model of which very few were made.

1987 My Version
The third-generation GSXR750 was the H. It had slightly different cosmetics
(fairing lower in particular), a larger 21It tank instead of 191t and a longer
swingarm. However, the engine was unchanged. The biggest criticism of the first three models of the GSXR750 was a poor quality rear shock.

1988
The big change came with the GSX-R750J. A new short-stroke engine was
introduced with 73.0 x 44.7mm dimensions, thinner piston rings, bigger main
bearings and big-ends to give a 38-percent stiffer crankshaft, 2.5mm bigger
inlet valves and 1.Omm bigger exhaust valves (same as the 1100), new camshafts
with higher lift, a 50 percent bigger oil-cooler, and 36mm constant-velocity
semi-flatslide 'Slingshot' carbs.
The chassis was also all-new with 43mm forks instead of 41 mm, a stronger frame
with a 40mm shorter wheelbase, and the engine was mounted 25mm lower. Wheels
became 17-inch with a 3.50 front and a 4.50 rear. A new slippery fairing shape
improved aerodynamics, there was a remote front brake master-cylinder and power
was up to a claimed 112bhp at 11,000 rpm.
Drilling the carb slides certainly unleashed some extra ponies (for the
racetrack only of course!) . The J wore a four-into-two exhaust rather than the
F's four-into-one 'garbage can' muffler, and weight was up to 195kg.

1989
The GSXR750K's major change was limited to new exhausts with 'gold' outer
sleeves. The new system offered four degrees more cornering clearance - a
complaint with the J. weight remained at 195kg.
Suzuki also entered the Superbike 'homologation' war with the GSX-R750RK in 1989
(known more commonly as the RR). It was designed to counter the likes of Honda's
RC30 and Yamaha's OW01, but failed to grab the interest of private owners to the
same degree.
The R's engine returned to the 'long-stroke' dimensions of the F/G/H models,
sporting exotic internals, 40mm CV carbs 120bhp and 187kg.

1990
The GSX-R750L brought nearly as many changes to the GSX-R lineage as did the
1988 J. Up front were the first readily available upside-down forks on a
streetbike, there was a four-into-one chamfered exhaust, a steering damper, and
most importantly, a return to the long-stroke engine heralded in the RK (70.0 x
48.7mm).
The L also had 2mm bigger carbs at 38mm (but still 2mm less than the RR), and
slight geometry changes with 25.5-degree rake instead of 24.9- degree, and 100mm
of trail instead of 99mm. The rear wheel became the de rigueur 5.50 x 17.
Weight was down to 193kg and the smaller bore meant slightly smaller valves to
increase the gas velocity. Power was up to 116bhp at 11,OOOrpm, but sparkplug
size was down from 12mm to 1Omm. The inlet cam stayed the same, but the exhaust
sported 1.2mm less lift in the quest for more torque and a broader spread of
power.
Surprisingly, the redline was still 13,000rpm despite the longer stroke, but the
new conrods used threaded cap bolts rather than through bolts for greater
strength and lightness. There were lighter pistons, a lighter valvetrain, a
large-capacity oil pump and a bigger curved oil-cooler.

1991
This year brought some major styling changes to the GSXR, the M-model sporting
a 'shovel snout' and twin taillights. Internally, there were now underslung
sliding rockers (rather than the forked rockers of the L) which beared directly
on the valve, with shim adjustment. Stronger valve springs were substituted, and
the exhaust cam carried seven degrees less duration.
The M's chassis remained the same as the L, but claimed weight was 15kg heavier
at 208kg. A more comfortable seat was a welcome addition, with seat height
dropping from 795mm to 790mm as an added bonus.

1992
After eight years of oil-cooling, the advent of the GSXR750W heralded (as the
initial suggests) the arrival of water-cooling. As well as other restyling, the
WN saw major changes to the engine room with downsizing of the mill
while retaining the M's 'long stroke' configuration.
Compression was up to 11.8:1, pistons were lighter, its airbox was bigger and
the valve-stem diameters shrunk. All this saw an extra 2bhp extracted from the
WN, with claimed peak power now 118bhp at 11,500rpm and maximum torque of 8.0kg-m at 9500rpm.
On the chassis side, the trademark frame was retained with larger
pentagonal-section tank rails and beefier castings at the steering-head -
according to Suzuki yielding a torsional increase of 24 percent. The trickest
part however, was the built-up pressed asymmetrical swingarm. Oh, and seat
height was down another 1Omm to 780mm.

1993
More of the same for the P-model update of the first generation of water-cooled
GSXRs. Essentially just a cosmetic make-over with only colour changes.

1994
Much more than just the obligatory two-year update the '94 GSXR750WR came with
a multitude of engine, chassis and running gear changes. Along with a new engine
mount for the magnesium (not aluminium) cylinder-head cover, the WR also sported
new magnesium breather and ignition covers.
In a full engine redesign, last year's bike came with different spec sparkplugs,
wider piston-ring grooves, spring-steel first piston-rings rather than
stainless-steel, lighter conrods, a higher output Mitsuba starter motor instead
of the WP's Nippon Denso item, a smaller ignition rotor, stainless-steel header
pipes (with thinner walls) rather) than carbon steel, and a plastic sprocket
cover instead of aluminium.
Other gearbox updates included a lighter primary gear, new counter-shaft,
four-dog second gear instead of three, revised and lighter fifth and sixth
gears, and a new clutch-release pinion, returning an all-up engine weight saving
of 2.35kg. Suzuki revised its claimed performance figures in 1994, and despite
all the WR's engine updates the 194 bike claimed just 112bhp at 10,500rpm - some
6bhp less than its predecessor.
94's GSXR750 boasts a number of chassis updates also, including larger
diameter inner fork tubes with thinner walls (43mm instead of 41), smaller
diameter outer fork tubes (51.5mm instead of 52.5), revised fork spring and
damping rates, 1mm thinner triple-clamps, revised rear shock spring and damping
rates, a new swingarm, and a 25mm-diameter swingarm pivot shaft rather than
20mm. A swag of running gear updates rounded out the '94 bike, including a
repositioned instrument cluster on the frame rather than triple-clamp, a smaller
battery and smaller-diameter headlights with no inner lens. These changes saved
some 2.55kg alone.
Other new bits included a centrally-mounted steering damper, six-piston front
Tokico callipers rather than four-piston Nissins, drilled front discs rather than
slotted, a 1mm thinner rear disc at 5mm, Dunlop D204 radials instead of Michelin
59-series radials (with 180/55 rear instead of 170/60), lighter wheels with
modified spoke shape, and a narrower frontal area of fairing. Reduced thickness
in some sections of frame led to a claimed 1.8kg weight saving with no loss of
rigidity while total chassis weight reduction was a claimed 4.2kg, leading to
total weight loss of 9.1 kg over the WP model (down from 208kg to 199).

1995
Suzuki's GSXR750 series enters its second decade, with the '95 GSX-R750WS
sporting a new exhaust system and jetting changes to claim peak torque of 8.1
kg-m at 9500rpm and maximum power of 120bhp at 10,500rpm - some 8bhp more than its predecessor, but just 2bhp more (at 1,OOOrpm less) than the 1992 WN.
With graphic updates and different front brake pad material.