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Suzuki GSX-R750 History

Suzuki GSXR 750

When the first GSX-R750 appeared at the Cologne motorcycle show, heads turned and crowds converged at the Suzuki stand in awe of the blue and white GSX-R. With  dry weight of 176kg, the lightweight aluminium framed GSX-R shamed the 750cc competition such as Kawasaki's GPz750 (241kg) and Honda's VF750 (218kg). That combined with a mini-malist air/oil cooled 100bhp engine, meant the GSX-R was the bike the racing fraternity must have for the upcoming 85 season. The endurance styling, meanwhile, was enough to convince road riders to sign their wage packets over to finance houses.

The GSX-R's racing career in the UK started  when the 41-year-old Mick Grant, who went on to win the 1985 Superstock series, finished second in the World TT F1 championship and won the IoM Production TT. He said: We got the bike early due to our links with Suzki. I didn't want to ride the production bike, but Suzuki insisted. I took it to a session at Donington. The oil filter came off and I fell off after four laps. In those few laps I knew the bike was head and shoulders above the competition. It was light and rapid despite the lower than expected rear-wheel power. By the time I'd won my forth race, rumours were flying that the engine wasn't standard. It was, it's just like the ignition box allowed another 500 rpm to be used. The organisers didn't want to do a stripdown, so in the end we got so fed up we stripped the bike ourselves in the pitlane.

1985-1987 - GSX-R750 F/G/H

  • Power -106bhp
  • Dry weight - 176 kg
  • Top Speed - 145.7mph
  • Engine: Air/oil cooled 749cc (70 x 48.7mm) inline-four, dohc, 16 valves, 29mm Mikuni flatside carbs.
  • Chassis: Aluminium cradle-type frame.

The GSX-R750 was derived from the factory's ally-framed XR41 GS1000R race bike. The 750 was the first mass-produced large Japanese multi to use an aluminium frame. The air/oil-cooled 749cc engine was based on the XR69 endurance 1000R bikes on 1981-82, with final engine tweaks gained from the Yoshimura-developed XR41, and 1984 750 F1 machine. For 1986-87 (G.H models) the bike evolved into a less nervous handler with bigger forks and a longer swingarm. Its looks remained virtually unchanged. Engine internals were also strengthened .

The first GSX-R750s were hardcore Race bikes with lights. As journalist Matt Oxley said at the original GSX-R's launch: It is as if Suzuki had thought, right, f**k being responsible.

1988-1989 - GSX-R750 J/K Slingshot

  • Power - 112bhp
  • Dry weight - 195kg
  • Top Speed - 150mph
  • Engine: Air/oil-cooled 748cc (73 x 44.7mm) Mikuni flatside carbs.
  • Chassis: Aluminium cradle-type frame.

In 1988 came a total ground-up version of the bike, signified by the rounder bodywork. Power output increased to 112bhp with the new short-stroke engine, and the chassis got strengthened, but the new model suffered from poor ground clearance.

The rear suspension was weak the damping and spring rates were way out. The revision also added 28kg of extra weight. But the bike was a lot easier to ride, with the extra mid-range from improved ignition and the change to 36mm Slighshot CV-based carbs.

The following K-model got uprated rear suspension and increased rear ride height. At the same time Suzuki rolled out another single-seat limited race version the GSX-R750R-K, retaining the long-stroke motor from the earlier three models.

1990-1991 - GSX-R750L/M

  • Power - 115bhp
  • Dry weight - 208kg
  • Top Speed - 149.5mph
  • Engine: Air/oil-cooled 749cc (70 x 48.7mm) inline-four, dohc, 16 valves, 29mm Mikuni flatside carbs.
  • Chassis: Aluminium cradle-type frame.

An altogether better machine from a myriad of changes the biggest was the return to a long stroke/narrow bore engine. Other mods included a stronger clutch, revised oil pump and larger oil cooler.

The extra power was the result of more revs from new pistons and conrods, with improved engine breathing starting with bigger 38mm carbs and a 4-2-1 exhaust.

Stronger frame bracing and the addition of stiffer USD forks (a production bike first) with decent damping adjustment helped the bike become a serious road and track tool again.

Steering geometry had been sharpened over the years and demanded the use of a standard-fit steering damper a pain at low speed due to its non-adjustability. But it looked great, particularly the M-model with its faired-in headlights.

1992 - GSX-R750WN

  • Power - 118bhp
  • Dry weight - 208kg
  • Top Speed - 157.5mph
  • Engine: Water-cooled 749cc (70 x 48.7mm) inline-four, dohc, 16 valves, 38mm Mikuni carbs.
  • Chassis: Aluminium cradle-type frame

Water-cooling didn-t help the dry weight (it was still a bloater at 208kg) but that and the retained piston oil-cooling paid dividends as the new slimmer engine rattled 160mph. Unfortunately Suzuki still had its corporate head stuck in sand with the cradle frame showing its age despite bigger frame rails and a pressed ally swingarm.

1996 - GSX-R750WT

  • Power - 130bhp
  • Dry weight - 179kg
  • Top Speed - 165.4mph
  • Engine: Water-cooled 749cc (72 x 46mm) inline-four dohc, 16 valves, 39mm Mikuni carbs.
  • Chassis: Aluminium twin-spar beam frame.

The 750 S-RAD came with a beam frame and was a return to what the GSX-R stood for: light, agile, powerful, more importantly, being a bloody hoot to ride fast. Weight was nearly down to where it all began and sharpened geometry and styling was claimed to mimic Kevin Schwantz's 500GP bike.

Chris Walker raced a factory Suzuki GSX-R750 in an epic battle with Neil Hodgson for the BSB title in 2000. Ultimately, a blown engine robbed him of the title. He said To this day the bike I rode in 2000 was the best I have ever ridden. It was an ex-factory bike and just felt so good from the moment I sat on it. I remember getting on it for the first time at a winter test and feeling instantly at home on it. This was the first time I had raced a bike with fuel injection and it meant the bike was very nice to ride and set up. A lot of what we changed on the 2000 race bike ended up changing on the following road bikes as hey become more focussed. I loved that bike.

1989 - GSX-R750 L/M

  • Power - 135bhp
  • Dry weight - 179kg
  • Top Speed - 167.6mph
  • Engine: Water-cooled 749cc (72 x 46mm) inline-four, dohc, 16 valves, 46mm efi bodies.
  • Chassis: Aluminium twin-spar beam frame.

Fuel injection gave more midrange tractability along with searing top end. The four throttle bodies worked superbly because Suzuki spent over a year developing the system. The frame was strengthened, suspension changed and a 5mm shorter wheelbase. The gearbox (close ratio) and final ratios were changed to suit the latest 135bhp performance.

2000 - GSX-R750 Y

  • Power - 141bhp
  • Dry weight - 166kg
  • Top Speed - 176mph
  • Engine: Water-cooled 749cc (72 x 46mm) inline-four, dohc, 16 valves, 42mm wfi bodies.
  • Chassis: Aluminium twin-spar beam frame

Dry weight down to the original F's and power up to 1000cc levels. The engine claimed the Slimfast title the cylinder head alone shed half a kilo. The overall result was a heady but safe 14,000rpm redline (conrods were shot-peened for strength). Throttle bodies went down from 46mm to 42mm and also held two sets of butterfly valves.

2004 - GSX-R750 K4

  • Power - 155bhp
    Dry weight - 164kg
    Top Speed - 177mph
  • Engine: Water-cooled 749cc (72 x 46mm) inline-four, dohc, 16 valves, 42mm efi bodies
  • Chassis: Aluminium twin-spar beam frame.

Feather-light 163kg shamed some 600s handling/1000cc performance tag. Once again the engine's internals were shaved of flab to extend the rev ceiling. Bigger ECU processing power made throttle delivery almost clinical. Black frame based on the  GSX-R1000's. Radial brakes introduced.

2008 - GSX-R750 K8

  • Cost - £8200
  • Power (claimed) - 150bhp
  • Weight (claimed) - 167kg
  • Torque (claimed) - 63.69ftlb
  • Insurance group - 15 (of 17)

Technical Spec

  • Fuel capacity - 17-litres
  • Seat height - 810mm
  • Wheelbase - 1400mm
  • Engine - Liquid-cooled, 750cc (70 x 48.7mm), 16v, dohc, in-line four. Fuel injected, 6 gears.
  • Chassis - Aluminium twin-spar frame. 41mm upside-down forks, fully adjustable. Single rear shock, fully adjustable (including high and low speed compression damping)
  • Brakes - 2 x 310mm front discs with four-piston radially mounted callipers. 220mm rear disc with single-piston calliper.
  • Tyres - 120/70 x 17 front, 180/55 x 17 rear.