The Suzuki GSX-R750 is more than just a motorcycle - it is the cornerstone of the GSX-R line. Indeed, it is the original GSX-R. When the original GSX-R750 was introduced in 1985, it established an entirely new class of machine. The GSXR750 took over the grid in production-based road racing worldwide, becoming the racebike of choice for an entire generation of roadracers.
And now, Suzuki introduces the all-new 2004 GSX-R750. Since the beginning, the GSX-R750 has been about overall balance of handling and engine performance. For 2004, the GSX-R750 takes that balance to an entirely new level with an improved compact, lightweight design that creates an awesome combination of handling, performance and style.
The '04 GSX-R750 retains its basic race-winning layout from the previous versions. It utilizes a bore and stroke of 72.0mm x 46.0mm, producing 749.2cc of displacement. The liquid-cooled powerplant continues to use four valves per cylinder, Suzuki Dual Throttle Valve (SDTV) fuel injection and aluminum cylinder bores electro-plated with Suzuki's own nickel-phosphorussilicon- carbide coating called Suzuki Composite Electrochemical Material (SCEM). Other competition-proven components include lightweight forged pistons mated to chrome-moly-steel, shot-peened connecting rods and a high-performance sixspeed transmission.
The 2004 GSX-R750 benefits from a series of refinements designed to reduce weight and mechanical losses, increase engine output and improve power delivery while reducing exhaust emissions. Thus, it is the most efficient 750cc engine ever built by Suzuki.
The refinements start with a more compact combustion chamber with a higher compression ratio of 12.3:1, versus the previous version's 12.0:1. The new combustion chamber requires a reshaped piston with a flatter crown and reshaped valves without indented head faces. Valve angles remain at 12 degrees on the intake and 13 degrees on the exhaust from the cylinder centerline. Valve size also remains 29mm on the intake side and 24mm on the exhaust end with a 4mm stem. The big difference is that the valves are now made of titanium instead of steel. Each intake valve weighs 7.2 grams less than its steel counterparts and the exhaust valves are 6.0 grams lighter for a combined weight savings of 105.6 grams. The big advantage comes in the reduction of reciprocating mass and inertia forces, which allows for higher maximum rpm with valve springs specifications that are 25 percent lighter in rate. That lighter spring rate means reduced mechanical losses and increased horsepower and torque. Valve springs are of a special steel-alloy construction and use aluminum retainers.
Lightweight hollow camshafts with thinner walls have internal diameters increasing from 15.5mm to 16.5mm. This produces intake camshafts that are 45 grams lighter and exhaust camshafts that are 35 grams lighter. Lighter pistons and a new piston-ring treatment also contribute to improved horsepower and higher rpm limits. The skirts on each forged piston are shorter overall, reducing piston height from 40.7mm to 39.2mm. Thinner walls mean the pistons are each 15 grams lighter for a total weight reduction of 60 grams. The faces of the top compression ring and oil control ring on each piston are now coated with chrome-nitride applied in a vacuum chamber using Physical Vapor Deposition (PVD). This chrome-nitride coating is harder and smoother than conventional chrome plating, resulting in reduced friction and increased durability.
Intake ports are 2 percent larger than before, with exhaust ports growing 2mm (32 mm vs. 30 mm). The distance between the centerlines (pitch) adjacent to the ports has been reduced for a more compact fuel-injection assembly. This allows the airbox and fuel tank to be narrower by 20mm at the rider's knees. The outside intake ports have been angled inward, reducing pitch between cylinders one and two, and between cylinders three and four from 80mm to 75mm. The pitch between cylinders two and three remain at 80mm.
New ventilation holes in the upper crankcase between the cylinder bores help to equalize crankcase pressure, reducing internal crankcase pumping pressure and increasing torque by about 2 percent. Handling the increased performance of the GSX-R750 is a new trapezoidal-shaped aluminum radiator developed in the factory racing department. The aluminum liquid-cooled oil cooler now has eight layers of coolant passageways instead of the previous model's six for improved cooling capacity.
The Suzuki Dual Throttle Valve (SDTV) fuel-injection system for the new GSX-R750 has also been upgraded for '04. Dual double-barrel throttle bodies replace the four individual units used on past versions, reducing weight by 370 grams and simplifying the throttle linkage. Internal dimensions remain unchanged. New injectors feature multi-hole tips instead of conventional pintle-type tips for a finer spray and better fuel atomization. A new Auto Fast Idle System (AFIS) improves cold starting, while a smaller and lighter ECM boasts a faster 32-bit CPU with 256 kilobytes of ROM for more precise and accurate operation throughout the rev range. Additionally, the crankshaft position sensor has 22 poles instead of eight for increased engine rpm signal accuracy.
The four-two-one exhaust system has stainless steel head pipes, collector and S-bend and features a new larger lightweight titanium cored and aluminum sleeved muffler with a slash cut tip. The change from steel to titanium muffler internals save 700 grams and the aluminum/titanium muffler is approximately 300 grams lighter than an all titanium muffler.
The GSX-R750's aluminum twin-spar frame is painted black and incorporates a cast steering head and plated swingarm pivot mated to a pair of extruded main frame spars. Each main spar has an internal reinforcing rib running lengthwise, dividing the frame into two separate internal compartments, allowing Suzuki engineers to adjust vertical and horizontal rigidity for improved handling and feel under hard braking and cornering. The main spars are taller and thinner than before and the rear subframe mounts are redesigned for improved durability. Wheelbase has been reduced from 55.5 inches (1410mm) to 55.1 inches (1400mm). Rake remains at 23.6 degrees while trail has been changed from 96mm (3.78 inches) to 93mm (3.66 inches).
Showa inverted 43mm forks are fully adjustable for spring preload, and rebound and compression damping, and produce 120mm of wheel travel. Out back, a matching Showa piggyback reservoir rear shock features the same adjustments and provides 130mm of wheel travel.
Tokico four-piston radial-mount front brake calipers and 300mm discs provide increased stopping power and reduced drag. Braking performance is further improved due to a racing-influenced radial piston front brake master cylinder. This unit more directly transfers lever travel into stopping power, creating improved brake feel. The rear brake uses a 220mm disc and a dual-opposed piston caliper mounted directly to the swingarm, eliminating the torque arm.
Wheels are made of cast-aluminum, with a 3.50 x 17-inch front carrying a 120/70ZR17 radial tire and a 5.50 x 17-inch rear wheel carrying a 180/55ZR17 radial tire.
The new GSX-R750's aggressive and distinctive new look features vertically stacked headlights that are narrower than before. This improves aerodynamics and reduces frontal area significantly. The latter allows for ram-air ducts to be positioned 10mm closer to the fairing centerline, providing maximum efficiency and increased airbox pressure. The multireflector headlights use a 60/55-watt H4 halogen bulb mounted above a projector low beam using a 55-watt H7 bulb.
The reshaped fuel tank is 15mm shorter and 20mm narrower at the rider's knees, providing better aerodynamics and increased range of motion. The overall seating position for the '04 GSX-R750 has been improved in that the seat-tohandlebar measurement was reduced for increased rider mobility. Out back a more compact LED taillight resides under a redesigned tailsection, completing the aggressive new look of the GSX-R750.
Instruments for the 2004 GSX-R750 include a stepping-motor analog tachometer, digital LCD speedometer, odometer/ tripmeter/clock combo, LED turn signal, high-beam, neutral and fuel level indicator, as well as a new LED rpm programmable LED rpm indicator light.
The 2004 Suzuki GSX-R750 - "Own the Racetrack, reborn."
GSX-R750 (K4) AT A GLANCE
Suggested Retail: $ 9,499.00
Engine Type: *Four-stroke, liquid-cooled DOHC, inline four-cylinder
Bore and Stroke: *72.0 mm x 46.0 mm
Front Brake: *Dual Radial Mount Hydraulic Discs
Rear Brake: *Single Hydraulic Disc
Wheelbase: *55.1 inches (1400 mm)
Dry Weight: *359.3 lbs. (163 kg)
* Specifications not final
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2004 Suzukis