Suzuki GSX-R 750

When the Suzuki GSX-R 750 was introduced in 1985, it was a total shock to the motorcycle industry. And the newest version of the bike, the 2011 GSX-R750, will continue to shock.

The original GSX-R set a design theme Suzuki engineers have followed with success ever since: Make the GSX-R respond to the rider and do what the rider wants, when the rider wants, how the rider wants. Concentrate on overall performance, not simple fashion. Take what is learned in professional racing, and apply it to production models in a continuous loop of engineering improvement.

In the decades since then, the GSX-R750 has consistently outperformed anything else in its class, proving the slogan, Own The Racetrack. Would-be competitors finally gave up racing against the GSX-R750, and then stopped building 750 Supersports altogether.

The 2011 GSXR 750 features advanced engine technology, with broader power delivery, improved throttle response, lower emissions and about 10-pecent better fuel mileage as measured by Suzuki engineers using the standardized Worldwide Motorcycle Test Cycle.

The new machine is built on a more compact, 15mm-shorter wheelbase with race-developed chassis geometry, suspension and brakes, with simplified and lighter aerodynamic bodywork.

The newest GSX-R750 is a full 8 kilograms lighter, with a curb mass of 190 kilograms.

Efficiency By Design
Efficiency is an important motorcycle engineering consideration.

Combustion efficiency, for example, is a measure of how completely an engine burns its fuel. Better combustion efficiency can increase power and torque output across the rpm range; improve throttle response, acceleration and fuel mileage; and reduce emissions.

Mechanical efficiency is a measure of how much of the power and torque produced by an engine actually reaches the rear wheel. Reducing mechanical losses by minimizing internal engine friction, reducing the weight of reciprocating internal parts and relieving crankcase pressure can increase mechanical efficiency, putting more of an engine's output to use actually moving and accelerating the motorcycle and also improving fuel mileage and reducing emissions.

Performance efficiency is best expressed by the power-to-weight ratio, or, the comparison of a motorcycle's output to a motorcycle's weight. The more power and torque the engine makes and the less the motorcycle weighs, the better the power-to-weight ratio becomes. In turn, a better power-to-weight ratio can produce stronger acceleration, better fuel mileage and reduced emissions in many situations.

A Lighter, More Compact Chassis
The new GSXR750 features a completely new chassis designs, based on a more compact, lighter twin-spar aluminum frame with a 15 mm shorter wheelbase. The GSX-R750's wheelbase is now 1390 mm.

Rotating the engine rearward by 3 degrees around the countershaft sprocket made it possible for the engineers to reduce the distance from the front axle to the swingarm pivot while maintaining the race-proven steering geometry and without losing the needed clearance between the front wheel and the radiator at full wheel travel.

The shorter wheelbase better centers the combined machine/rider mass between the wheels, improving racetrack cornering and also shortening the reach between the seat and the handlebars. The shorter reach and slightly wider handlebar angle make it easier for the rider to reposition their weight while on the racetrack and also improve comfort on longer highway rides.

Each GSX-R 750's main frame is built using five welded-together castings. But changes in the size and shape of the main spar castings and the relocation of the connecting welds contributed to a 1350 grams significant reduction in frame weight for each model and also allowed the engineers to adjust torsional rigidity and enhance racetrack cornering. Each frame is also narrower at the seat, making it more convenient for the rider to reposition their weight for cornering on the racetrack.

The aluminum swingarm is also 900 grams lighter, thanks to a simplified design using fewer welded-together, cast parts.

State Of The Art Engine Design
The inline four-cylinder engine is liquid-cooled with Suzuki Ram-Air Direct (SRAD) induction and a digital engine management system. Double Overhead Camshafts (DOHC) are driven by a link-plate chain off a forged crankshaft and open four titanium valves per cylinder through bucket tappets, with shim-under-bucket lash adjustment.

The valves are set at a narrow angle, 22.5 degrees for the GSX-R750, allowing a very compact Twin Swirl Combustion Chamber (TSCC)-with the intake valves set at 10.5 degrees from the cylinder centerline. The exhaust valves are set 12.0 degrees from the cylinder centerline.

The engine is oversquare, which means that it has a larger bore and a shorter stroke, producing a race-proven bore/stroke ratio which contributes to better efficiency and allows higher rpm.

High-compression, forged aluminum three-ring slipper pistons feature cutaway sides and ride on short wrist pins carried by shot-peened chrome molybdenum steel connecting rods. The rectangular upper compression ring and the oil control ring on each piston feature a chrome-nitride coating applied in a vacuum using a Physical Vapor Deposition (PVD) system.

The chrome-nitride coating is harder and smoother than conventional chrome plating, reducing friction and improving cylinder sealing; the rectangular upper compression ring is pushed out against the cylinder wall by combustion pressure, reducing blow-by and further improving cylinder sealing.

Each bore in the integrated aluminum-alloy cylinder-block/upper-crankcase casting is plated with Suzuki's own race-proven nickel-phosphorus-silicon-carbide coating, which reduces friction and improves heat transfer, durability and ring seal and is known as Suzuki Composite Electrochemical Material (SCEM).

Pentagonal cutouts in the sides of each cylinder bore are larger in terms of area than conventional round ventilation holes, allowing air trapped underneath each descending piston to more quickly escape to adjacent cylinders where the pistons are rising. The shape of the ventilation holes-wider at the top, narrower at the bottom-matches the actual flow of the trapped air, with more flow at the top and less at the bottom, and reduces pumping losses due to internal crankcase air-pressure resistance to downward piston movement. The larger ventilation holes also reduce overall crankcase weight.

The crankcases carry a six-speed close-ratio transmission with vertically staggered shafts, to reduce overall engine length, and a back-torque-limiting clutch.

The race-proven ramp-and-cam design of the back-torque-limiting clutch reduces pressure on the plates during deceleration, producing smoother downshifting and corner entry and allowing the track rider to concentrate on braking and cornering.

The four-into-one stainless-steel exhaust system features four individual head pipes and a single collector. The mid-pipe located between the collector and the under-engine exhaust chamber carries a Suzuki Exhaust Tuning (SET) servo-controlled butterfly valve to match exhaust system back-pressure to engine rpm, throttle position and gear position, maximizing torque and improving throttle response, especially in the low-to-mid rpm range.

The exhaust chamber leads to stainless-steel S-bend pipe and a titanium muffler shaped and positioned to enhance cornering clearance and improve aerodynamics. A reduction in pipe wall thickness and a smaller, more efficient exhaust chamber and muffler combine to make the GSX-R750 system 1100 grams lighter.

A slightly larger-diameter radiator fan mounted on the efficient, trapezoidal, curved radiator turns on and off based on coolant temperature and improves cooling performance.

Each GSX-R750 cylinder's two intake valves measure 29.0 mm in diameter while the two exhaust valves measure 23.0 mm in diameter. The redesigned intake valves are each 0.6 gram lighter thanks to a new, stronger titanium alloy and reshaped valve heads.

Advanced Digital Engine Management, Fuel Injection and Emissions Control
The GSX-R features a repositioned engine management computer (also known as the Engine Control Module, or ECM) to allow the wiring harness to be simplified and made lighter. The ECM operates a state-of-the-art Suzuki Dual Throttle Valve (SDTV) closed-loop fuel injection system, an advanced ignition system and several emission control systems, producing better throttle response, smoother power delivery, improved mileage and reduced emissions.

At the heart of the SDTV system are two linked, double-barrel downdraft throttle bodies, each cylinder getting its own tapered barrel carrying two butterfly valves and two compact fuel injectors.

The primary butterfly valve in each throttle body is linked directly by cable (which provides a positive, instantaneous connection between the rider and the machine) to the throttle grip operated by the rider.

The secondary valve is controlled by the ECM, which monitors engine rpm, primary butterfly valve position (or how much throttle the rider has selected) and gear position, then opens or closes the secondary butterfly valve incrementally to maintain the ideal intake air velocity for improved cylinder charging and more efficient and complete combustion. The result is more linear throttle response, increased torque and reduced emissions.

The latest fine-spray injectors each have 8 small holes for improved fuel atomization, which contributes to more complete combustion. The primary injector for each cylinder operates under all conditions, and the secondary injector adds more fuel during high-rpm, high-load operation.

The primary injector for each cylinder has been repositioned at a shallower, 35-degree angle from the throttle-body centerline, spraying atomized fuel below the primary butterfly valve and directly down the intake port, improving throttle response. Each cylinder's secondary injector is mounted at a 15-degree angle and is aimed to bounce sprayed fuel off the secondary throttle valve, improving atomization and combustion efficiency while also contributing to more linear throttle response.

The amount of fuel delivered by the injectors is determined by the ECM, and is controlled by injector on-time. The longer the injector is turned on and is spraying fuel, the greater the volume of fuel delivered to the cylinder.

Primary injector on-time is calculated based on engine rpm, intake pressure (vacuum), throttle position and readings from a sensor built into the exhaust system; the sensor monitors exhaust gas composition and allows the ECM to adjust fuel delivery for more complete combustion, reducing hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) emissions. Secondary injector on-time is calculated based on throttle position and engine rpm.

A new, technologically-advanced, transistorized ignition control circuit developed in MotoGP racing and built into the ECM offers finer calibration and maintains more precise and stable spark timing, across the range of engine temperature.

The system uses an individual ignition coil built into each spark plug cap and fires 10 mm NGK spark plugs. Each plug has a fine, iridium-alloy electrode that produces a hotter spark (resulting in more complete combustion and improved throttle response), and delivers about double the service life of a conventional spark plug electrode.

An automatic Idle Speed Control (ISC) system is controlled by the ECM, reading coolant temperature and regulating the amount of air fed into the throttle body idle circuits when the engine is started in cold conditions. The ISC system improves starting, reduces cold-start emissions and stabilizes engine idle under varying conditions.

Suzuki's proven Pulsed-AIR (PAIR) system is controlled by the ECM and injects clean, fresh air from the air box into the cylinder head exhaust ports, reacting with unburned HC and reducing CO emissions. The amount of clean air injected into the exhaust ports is calculated based on throttle position and engine rpm.

A catalyzer, or catalytic converter, is built into the exhaust chamber mounted underneath the engine, to further reduce HC, CO and NOx emissions. The effective engine management and emissions control systems make the new GSX-R models cleaner-running.

S-DMS Rider-Selectable Mapping
The Suzuki Drive Mode Selector (S-DMS) system built into the ECM allows the rider to use a button mounted on the left handlebar switch module to select one of two engine control maps, regulating the fuel injection, secondary throttle valve and ignition systems. The two maps are designated A and B, with Map A delivering full power and acceleration and Map B producing more moderate acceleration.

The S-DMS system allows the rider to select a map to suit various riding conditions and personal preference on the road, for example choosing one map for highway cruising and the other map for tight country roads.

The two available maps were also developed using racing experience. Switching from one map to the other is instantaneous, making it possible for the rider to use one map on one part of a racetrack and then select the other map for another part of a racetrack, useful in case of localized rain in only a few corners.

The system also allows the rider to switch from Map A to Map B to suit conditions at the end of a long race when the rear tire is worn, to use Map B when scrubbing in a new rear tire, or to choose Map A for a high-speed racetrack and Map B for a tighter racetrack.

The Latest In Fully Adjustable Racing Suspension
For the first time, the Suzuki GSX-R750 comes with the revolutionary, race-developed Showa Big Piston Front-fork (BPF) inverted front suspension system. Conventional inverted front forks use a cartridge assembly that fits inside the fork leg on each side and typically incorporates a 20 mm piston to control damping.

The advanced BPF design eliminates the separate internal cartridge assembly inserted into each fork leg and instead uses a single, 37.6 mm piston riding against the inside wall of the 41 mm inner fork tube.

The larger BPF piston and valving shims produce more effective, more accurate and more linear damping performance. The more controlled compression damping is especially noticeable during hard braking and at corner entry, delivering better feedback to the rider.

The BPF design also has minimized change in internal fork pressure throughout the stroke, improving response to small bumps and racetrack surface imperfections. And because the fork springs are relocated to the bottom of each fork leg where they are completely submerged in oil, foaming is reduced and damping performance remains more consistent.

Because the piston is located above the fork springs, maintenance on the racetrack takes less time. Rebound and compression damping can also be externally adjusted, using convenient screws built into the fork caps

The BPF forks installed on the newest GSX-R750 are 1040 grams lighter than the conventional cartridge forks used on the previous model. The weight reduction is helped by the use of an external nut to secure the redesigned and lighter front axle, versus screwing the previously used front axle into a reinforced boss built into the fork leg.

The single Showa rear shock features externally adjustable rebound and compression damping, along with adjustable ride height. The threaded spring seats used to adjust preload are now made of anodized aluminum alloy instead of steel, reducing weight by 90 grams. The spring itself is also 200 grams lighter and a new shock linkage is 490 grams lighter.

Suspension response is also improved by a 550 grams reduction in unsprung weight, thanks to a 210 grams lighter front and 190 grams lighter rear cast aluminum wheel set and a 150 grams lighter rear sprocket drum assembly.

Unsprung weight-which is the weight of the components between the suspension (or springs) and the pavement-has a huge effect on each wheel's ability to stay in contact with the racetrack surface. More contact means more traction, which is especially important when accelerating out of a corner on the racetrack, or when trail-braking into the apex of a corner on the racetrack.

An electronically controlled steering damper uses the ECM to monitor motorcycle speed and adjusts itself for lighter steering at slower speeds and in parking lots, and delivers more damping force at racetrack and highway speeds.

Fully Floating Front Disc Brakes, with Radial-mount Brembo Monoblock Calipers and Adjustable Controls

The new Suzuki GSX-R750 comes with 310 mm fully-floating front brake discs and new radial-mount, four-piston Brembo monoblock calipers. The 32 mm caliper pistons are staggered to promote even pad wear, the trailing pistons offset relative to the pad centerline.

The monoblock design of the new calipers makes them lighter, and their more rigid construction and increased piston area improve braking performance by providing the rider with more consistent power and better feel at the lever.

The front brake master cylinder uses a 17.46 mm radial-mount piston. The position of the front brake lever relative to the handlebar is 6-way adjustable, using a convenient adjustment wheel. Combined, the new front brake calipers and associated hardware are 405 grams lighter than the system used on previous models.

The single 220 mm rear disc works with a new, lighter Nissin single-piston caliper that is 325 grams lighter than the caliper used on previous models.

Adjustable footpegs can be moved into a choice of three different positions in a 14 mm horizontal and vertical range, contributing to rider comfort with a more relaxed seating position on the street or allowing more cornering clearance and a tighter tucked-in position on the racetrack.

The rear brake pedal and master cylinder move together with the right footpeg assembly, and the shift lever linkage can be adjusted to accommodate changes in the left footpeg position.

Sophisticated Instrumentation, Featuring A Built-In Lap Timer
The new, more compact and lighter instrument cluster installed on the GSX-R750 now comes standard with a built-in lap timer/stopwatch and a programmable, sequential engine rpm indicator system. Both those new features can be useful at track days or during club-racing weekends.

The lap timer/stopwatch can be conveniently triggered using a button on the right handlebar switch module. The engine rpm indicator system's four LEDs can be programmed to go off at four different rpm settings, with a choice of a solid or blinking light. LED brightness is also adjustable.

The centerpiece of the instrument cluster is an analog tachometer, with an adjacent LCD panel offering digital speedometer, odometer, dual trip meter, reserve trip meter, clock, coolant temperature/oil-pressure indicator, lap timer/stopwatch, S-DMS indicator and gear position indicator displays.

Other LED lights built into the cluster include neutral, high beam and turn signal, fuel level and FI indicators.

A rolling-code anti-theft immobilizer system is standard in selected markets, with an additional LED indicator light built into the instrument cluster.

Lighter, Simpler Bodywork With Improved Aerodynamics
Both the new Suzuki GSX-R750 features exciting, aerodynamic styling and are even more streamlined and even more compact. The wind-tunnel development of the new model bodywork was done with a rider in place, because a motorcycle won't move very far or very well without a rider.

The work centered around giving both new GSX-Rs smaller, simpler and lighter bodywork, without losing any aerodynamic efficiency.

The bodywork is shorter front to rear to match the shorter wheelbase, but front overhang is also reduced by 55 mm and rear overhang is reduced by 35 mm. Seat height remains a relatively low 810 mm, and the top of the redesigned 17-liter fuel tank is lower, allowing the rider to tuck more completely.

The simplified bodywork uses fewer, thinner parts and panels with less overlap and fewer seams, requiring fewer fasteners and clips, while still passing strict Suzuki quality and durability tests.

A new combination of smooth, curved lines with sharp edges and special attention to improving air flow along the side panels and lower cowling paid off by making it possible to significantly reduce bodywork surface area, saving even more weight.

Returning to a vertically-stacked dual headlight layout helped save additional weight without any performance penalty. And when the engineers were finished, each set of new GSX-R750 bodywork and associated external parts weighed an astonishing 35% less (a full 3,400 grams) than the equivalent parts used on previous models.

Lighter Weight Equals Better Performance
The importance of reducing curb mass by 8 kilograms for the new GSX-R750 cannot be overstated. The integrated design team of talented Suzuki engineers analyzed every engine, chassis and electrical part, component and assembly. Could it be made lighter, smaller, simpler while maintaining strength and durability?

It was detailed, painstaking work, and the result was better overall performance. On the racetrack, less overall weight contributes to harder acceleration, stronger braking, quicker handling. Which can make the difference in getting to the finish line sooner.

The Total Package
Designing a Supersport to Own The Racetrack isn't simply a matter of bolting together parts. It takes a total package, every feature contributing to helping the rider turn faster laps around the racetrack.

Consider the scene at a racetrack near you: The rider swings a leg over the latest GSX-R and warms up the engine. Clicking the bike into gear, he heads out onto the course, quickly upshifting through the close-ratio six-speed transmission and accelerating hard toward turn one.

At just the right point, the rider brakes hard and downshifts rapidly, the powerful, radial-mount Brembo front brake calipers scrubbing off speed while the GSX-R's back-torque-limiting clutch and BPF front forks help keep the wheels in line as the rider turns into the corner. Just past the apex, the rider rolls on the throttle and accelerates quickly over ripples in the track surface, the effective suspension and an electronically controlled steering damper helping the GSX-R smoothly follow the rider's selected exit line.

It could be during a track day for fun and excitement, or during a national race weekend for purse money and championship points. It is the product of Suzuki's integrated design approach, and the goal of every GSX-R: Own The Racetrack.

MCN Review
After years of gentle evolution Suzuki has gone to town on its 2011 GSX-R750. Weighing in at 190kg, fully-fuelled and ready to go, it’s a massive 8kg lighter than the old model, giving the 148bhp GSX-R750 a mouth-watering power-to-weight ratio.

The 750’s rolling chassis and bodywork is completely new, but it doesn’t get the GSX-R600’s radical engine overhaul and the resulting 1kg extra weight reduction. Aside from minor revisions to make it breath more easily, the 750’s motor is essentially the same as before, but it now promises to spin up faster and make more low and midrange power. Suzuki claims it’s 10% more fuel efficient too. It still has the perfect mix of power and handling, but thanks to the lighter weight, acceleration is now more towards a superbike than a 600. It doesn’t have the new close-ratio gearbox fitted in the 600, so feels longer-legged in the higher gears on track, but will it will make for a less frantic machine on the road.

It’s fun, fast and handles beautifully, but crucially it’s very easy to ride fast, unlike a bigger sportsbike. Pound-for-pound we reckon it’s one of the best sportsbikes you can buy.

Engine
Unlike the 2011 GSX-R600 there are only minor changes to the 148bhp, 750cc inline-four-cylinder motor. It now has pentagonal-shaped ventilation holes in the block, instead of round, which they say reduces pumping losses inside the engine and creates more bottom end power.

The primary injector nozzles are changed from 41 to 35 degrees inside the throttle bodies. The gearbox remains the same. A revised, more efficient ECU has been moved from under the seat to the top of the airbox to save weight on the length of wiring loom.

Blip the throttle and you still get that angry, metallic GSX-R rasp from the airbox and exhaust. The revs spin up almost as quickly on the move, racing through the gears, as it does at a standstill. The GSX-R750’s performance is as much as you’ll ever need on the road or track.

It’s still civilised, comfy and thanks to adjustable footpegs, roomy enough for tall riders too. The suspension is plush on the move and there’s lots of adjustment for track riding too. Showa Big Piston Forks give lots of support and feel, while Brembo Monobloc calipers are a big improvement over the old model’s brakes. They still fade on track, but not as much as before. With much less weight to lug around, the GSX-R750 is a joy to ride fast. It loads you with feedback and flatters your riding. There are few bikes that can cover ground as fast and are such fun at the same time. The new chassis has a 15mm shorter wheelbase, so steering is even lighter than before. In the real world, the GSX-R750 is every bit as fast as a 1000.

Equipment
Compared to the latest 1000s, the GSX-R750 is sparsely-equipped, but that’s the way it’s supposed to be: it’s light, simple and fast. It does have a speed-sensitive, electronic steering damper and two power maps, which are easily switchable from the left bar. There’s a new dash, which incorporates a gear position indicator and lap timer and of course those Showa forks and Brembo brakes.

Source MCN