If it ain’t broke, it doesn’t have enough power yet – The quest for speed.

This year we’ve had the pleasure of following one of our youngest members on his crusade to build a winning 300bhp turbo wheelie bike based on a GSXR1100 Slingshot from the 1990’s. We all watched in amazement as the master plan took shape and we rode the roller coaster with him throughout the year.His determination and focus was such that  it soon became clear he was either going to break a record, break his engine or break himself.

Fortunately he managed the first 2 and not the 3rd. Here’s Kev Kearsley’s round up of  his 2016 campaign. He went into this  year as the Kid Kearsley but nobody can deny that he came out the the other side Da Man!

The Quest for Speed

Kev Kearsley

Ever wake up and think I’m going to do 200mph today? Tuesday was one of those days.

The Top Speed Tuesday put on by Straightliners at Elvington marked the last event of the year for myself, and what a year.

With numerous top speed days for tuning the bike for the Wheelie Comp, seeing a failed 194mph kilometre wheelie for dropping it a few metres short of the required distance.

A trip to Pendine sands in South Wales where I set two land speed records reaching 174mph on sand.

Hundreds of miles on the road two up

A track day at Oulton Park in the soaking wet, 300bhp on summer race tyres in the wet is not advisable Kid.

A few static displays at various motorcycle shows to fly the OSS banner including Donnington where my alter ego Rene took the old girl for a few laps of the track.

Many visits to RTR motorcycles for dyno runs, one off which was for the OSS dyno day where the bike made 300bhp.

So all in all a good year! Just think of the stress that engine has had doing all that, the only fault I got all year really was a leaky block so I’d say quite a reliable one.

Lets go out with a bang! I had that shit or bust attitude on.

It had been raining all Monday night making it look like the event would be cancelled, that gut wrenching feeling driving to the track in the rain for 2 hours thinking this ain’t gunna happen today. The rain stopped thankfully and after waiting a few hours to allow the track to dry we were given the all clear to attack the track.

The bike is, as a few of you know, made for wheelies, this means a short 55″ wheel base and big horsepower, not an ideal combo for Land Speed Racing.

Time to do the job. I was waved off by the starting Marshall after sat staring down a 3km runway. Short shifting 1st, 2nd, 3rd into 4th with a little wheel spin as the track was cold and still damp, into top gear and the bike is now naturally wanting to wheelie up in the air, feathering the throttle on and off to try keep the front wheel planted was an impossible task.

kk-speed-1I felt gravity some what take over just shy of the line and I managed to pin the the throttle open all tucked in with my chin on the tank as I had no fairing to hide behind.

kk-speed

Made it. Still alive. Slowly throttle off as not to upset the bike, heart beating, did it do 200?? That drive back to the pits and the timing office seems to take forever.

203.8mph! On an unfaired 30 year old motorcycle with a well and truly abused engine.

kk-times

Thank you to all involved over the past year for parts, advise and food.

Use the link below to view the onboard action.

https://drive.google.com/file/d/0B0QcmiqJi-rISzdsMzdYTkJscU0/view

 

Don’t fear the fibre

There comes a time for many early GSXR owners when replacement plastics are required, leaving us with the difficult decision of chasing a wallet-blinding original in pocket-driven condition or going after market.

We are pleased to assist in making that after market decision that bit easier by welcoming Fiberman – Fiberbike Modifications – to the trader section.54ipped direct to you from Ireland, Fiberbike Modifications – here’s a list of some of the pieces currently available.

  • 1985  GSXR 750F solo seat cowl
  •  1986 – 88 GSXR solo seat cowl
  •  1985 – 88 GSXR Soloman seat unit
  • 1988 – 90 GSXR solo seat cowl
  • 1990 – 92 GSXR solo seat cowl
  •  1985 – 88 GSXR 3/4 fairing
  •  1991 – 1992 GSXR clock shroudslabby-34-fairing

Keep your eyes peeled for a competition coming up shortly to win a Fiberbike Modifications slabside seat unit of your very own.

In the meantime, why not head over to the Trader Section for more information on what Fiberman could do for your Old Skool Suzuki? Click here for the Trader’s Thread.

A Look At The Bike That Started A Revolution

The Champ And The Kid
A Look At The Bike That Started A Revolution
By David Swarts

1Kevin Schwantz checks out the 1986 GSXR750 while Ben Spies uses the
2000 GSXR750 to shadow one of his racing idols.

“Lighter is better” seems to be the latest big thing in sportbike design. In the rush to embrace this recent “new” trend toward lighter and lighter sportbikes, it’s easy to forget that shockingly low weight was a key feature of the 1985 Suzuki GSXR750, a bike brought to life under the direction of Etsuo Yokouchi and credited with creating the racer-replica category. Although most of the world got the GSXR750 in 1985, the United States had to wait until 1986. The 2000 GSXR750 therefore marks the 15th anniversary of the model line in the U.S. Over the years the GSXR750 has taken over 750cc production-based racing and has now been re-born stronger than ever to start a new century of competition on the racetrack and the dealership floor. Roadracing World decided to re-visit this historic line of motorcycles from behind the bubble, taking a fleet of various year-model GSXR750s to Henderson, Texas’ Oak Hill Raceway with former 500cc World Champion Kevin Schwantz, now 35 and originally from Houston, and new young gun Ben Spies, 15, from Longview, Texas. Comparing the perspective of the champ and the kid should prove enlightening. “The main concept of this machine is born on the circuit, and returned to the circuit,” were the words of Yokouchi. Yokouchi was a strong advocate of racing and high performance, and his design team set out to take what the company had learned through racing, particularly endurance racing, and apply it to a revolutionary streetbike. Yokouchi was also well known for demanding perfection from his design team and for rejecting design details that didn’t meet his expectations.

2The original, cradle-type frame used on the 1986 GSXR750.
Compared to the steel frames used by other manufacturers,
the GSXR750 frame’s weight of 18 pounds was astounding.

Aluminum frames were already around in the early 1980s and in theory an aluminum frame was lighter and stronger than the steel-tube units that were the status quo. The problem was producing an aluminum frame that could handle relatively high horsepower and in a cost-effective manner. Suzuki engineers learned to incorporate aluminum castings along with extruded tubes to reduce the number of parts needed to make a frame from over 90 on a steel example to 26 on the GSXR750. Suzuki’s engineers also developed their own unique alloy, which eliminated the need for a final heat-treating process. In 1983, Suzuki produced the first production bike with an aluminum frame, the two-stroke RG250. In 1984, Suzuki followed that up with the domestic-market, alloy-framed GSXR400. Then, at the 1984 IFMA motorcycle show in Cologne, the world got its first look at the GSXR750.

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The original GSXR750, with an aluminum alloy frame and unbelievably low weight.
The inspiration for the GSXR750 was the 1982 Endurance World Championship-winning GS1000R XR41 works racer. The aluminum frame of the 1985 GSXR followed the lines of the racer’s steel tube frame. The streetbike’s dual headlights were a feature only used previously on endurance machines. The GSXR750’s racing heritage was also the reason why it sported an 18-inch front wheel while 16-inch fronts were in fashion. Why? Simply because during an endurance race pit stop, it was easier to remove the calipers from the rotors on an 18-inch wheel. That exotic aluminum frame, meanwhile, weighed in at a mere 18 pounds, 19 pounds fewer than the 1985 GS750’s steel tube frame, and only cost $100 more to produce. Another key factor in the light weight of the original GSXR750 was the use of oil cooling. An air-cooled engine’s performance was limited by heat, but Suzuki engineers felt water-cooling added too much weight and complication. Why not just use the oil that’s already in the sump to cool the engine along with traditional air-cooling? The Suzuki engineers identified the most critical areas to be cooled inside the engine, increased the oil capacity, developed a dual-stage oil pump for their unique needs, and called their creation Suzuki Advanced Cooling System (SACS). The first part of the oil pump circulated oil to the engine’s moving parts like normal while also spraying the undersides of the pistons. The second stage sent oil to high-volume nozzles that sprayed the critical areas on the topside of the combustion chambers. The new cooling system helped make horsepower by allowing the use of smaller, lighter pistons and a higher compression ratio. Suzuki engineers also drew from off-road racing experience, incorporating the flat-slides used in RM motocrosser carbs into the GSXR750’s CV carbs, improving throttle response and fuel atomization. The GSXR750 also featured the Twin Swirl Combustion Chamber (TSCC) cylinder head design introduced on the 1980 GS1100.

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The first GSXR750 was powered by an air/oil-cooled Inline Four.
This drawing shows how a high-volume flow of oil was routed through
the cam case and across the top of the combustion chambers,
carrying away heat.
The new 1985 Suzuki GSXR750 had a claimed dry weight of 388 pounds (2.0 pounds under the AMA Superbike minimum weight limit of the time) with 106 claimed horsepower. Both numbers proved to be a little different when the bikes reached the hands of journalists and were weighed with fluids and run on independent dynos, but the numbers remained a landmark for power-to-weight. Magazines reported about 80 horsepower at the 140/70VR-18 rear Bridgestone with the bike tipping the scales at 423 pounds with oil but no fuel. Although the power was about 5.0 horsepower behind the class-leading Yamaha FZ750, the Suzuki weighed about 55 pounds less than the Yamaha and nearly 100 pounds less than the Honda VF750F Interceptor. In terms of straight-line speed, the Suzuki made up for its less power with less mass and equaled the Yamaha in the quarter mile and top speed. When it came time to tackle a curvy road or racetrack, the Suzuki’s suspension allowed the GSXR750 to pull away. The Suzuki featured a NEAS/PDF anti-dive system on the front forks (aka New Electronically Activated Suspension/ Positive Damping Force); the system was activated when the brakes were applied and restricted an oil passageway in the forks to reduce nose dive. In back, the GSXR750’s steel-bodied shock worked well through a Full Floater progressive linkage, but it quickly overheated and faded. Maybe the most important feature that came with the original $4499 GSXR750, and continues through the 2000 model, was the Suzuki Cup contingency program. This support program helped start the careers of many racers with millions of dollars in cash payouts and a highly publicized final round each year. When you mention Suzuki and racing in the same sentence, the name Kevin Schwantz usually appears before the period. Schwantz has had a big impact on the sport, his career spanning early days as a flat-tracker and trials rider to club road racer to Yoshimura Superbike pilot to Daytona 200 winner to 1993 500cc Grand Prix World Champion. Schwantz’s Grand Prix Number 34 has been retired by the FIM and a corner of the Donington Park road course has been named for him. Roadracing World Editor John Ulrich had a big influence on launching Schwantz’s professional career when Schwantz was 19 years old.

5Kevin Schwantz en route to winning the 1988 Daytona 200 aboard a
Yoshimura Suzuki Superbike.

To contrast Schwantz’s vast racing experience overall and first-hand knowledge of several GSXR750 models, we picked one of the youngest professional racers anywhere. At 15 years old, Team Valvoline EMGO Suzuki’s new signing Ben Spies is about as young as they come. Spies’ credits include several CMRA regional Championships, several CMRA lap records, the 1999 WERA Formula Two National Championship, and limited experience on production-based racers. Beyond that, Ulrich says that Spies has the same type of natural talent that caught his eye when he first saw Schwantz in 1984.

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Ben Spies was excited after riding the 2000 GSXR750 and immediately started
plotting his AMA Supersport debut. The only catch is that he’d have to wait until he turned 16.
The motorcycles for our racetrack party were sourced mostly from members of the Central Motorcycle Roadracing Association (CMRA). There is a lot of motorcycling history in Texas. Subjective testers of the day were impressed with the original GSXR750. In February 1986, Cycle reported, “…the GSXR steers with remarkable lightness, handles even sand-strewn, bumpy corners with confidence-inspiring predictability and accuracy. Crisp carburetion makes throttle transitions smooth and controllable,” and “�a feel of mechanical unity is at the core of the GSXR,” and “Significantly, less weight allows the bike to perform-engine-wise-at the same level as the more powerful FZ. This Suzuki convinces us that the future is low mass. The puzzling thing about the GSXR is its ‘racebike’ format. The GSXR’s riding position demands total commitment from the rider, and maybe that’s why Suzuki labels the GSXR a racebike for the streets.” For 1987, the GSXR G-model got bigger carbs (31mm to 34 mm), bigger brake rotors (296mm to 310mm), new header pipes, and slightly more power for $400 more or $4899. In 1987, Yoshimura Suzuki’s Kevin Schwantz took second in the AMA Superbike Championship by winning five of nine races, taking two second-places, but DNFing (crashing) while leading at Daytona and Laguna Seca. After riding David Wilson’s 1986 GSXR750 for our test at Oak Hill, Schwantz said, “I’m pretty surprised at how it handles. It seems like it does all of the basic stuff pretty well. It’s been 15 years, but I seem to remember them doing a lot stranger things when I rode them before. I had some good memories of the ’86 model, some bad ones, too. This one’s not bad. It’s a pretty decent bike.” After a second ride where he and Spies mixed things up a bit between the 1986 and 2000, Schwantz added, “The first ride was just making sure everything was normal on it. The second ride we started to have a little fun. It feels like it does the basics really well. It wasn’t doing anything really silly. I think you could have some fun riding it, and maybe some fun racing it. I don’t remember racing the ’86s that well. I always remember struggling to get it to handle the way we wanted it to. It feels like if you pushed it a lot harder, you’d come to do a fair bit of adjusting suspension-wise. Nothing that you couldn’t make work anyway. It does feel remarkably light. I can’t remember what the weight was on them back in ’86. I just remember we had to run a bunch of lead on the bottom of them to make them legal for AMA racing. It’s gonna be interesting to get on the 2000 and see how much more power there is. The weight should be pretty close, so the big difference will be the power.” Spies wasn’t born when this motorcycle was in the showrooms. After his first ride on the 1986, Spies said, “Wow! I just rode a time machine! Actually, I was surprised. I thought that it was going to be really hard to ride. The biggest thing that I noticed was that the power and carburetion wasn’t as good as my racebikes. Once you were in a corner, you had to keep pulling the bike into the corner. I was surprised. It doesn’t handle that bad, and it had pretty good power for something Fred Flintstone might have raced. I would have to pass if somebody asked me if I wanted to race this bike, well, maybe just for fun.”

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Teenage Texan Ben Spies backs what he called “the time machine”
down the hill leading into turn five at Oak Hill Raceway.
Spies was not yet born when this 1986 GXR750 was built.

 

Owner Wilson enjoyed watching Schwantz ride his bike, saying, “It’s exciting. I’m enjoying it. I’m enjoying watching him on the bike. There’s nothing like meeting a 500cc GP World Champion face-to-face, then having him ride your bike on the track.” Wilson’s bike was in stock, street condition except for a Yoshimura exhaust, a jet kit, a steering damper, and Avon tires on the 18-inch wheels. Suzuki engineers completely re-thought every bolt of the GSXR750 for 1988. They started with a new frame to replace the old unit, which was prone to flex too much under racing conditions. In fact, Schwantz’s 1988 GSXR750 Superbike’s frame had pieces from another GSXR’s frame cut and welded onto it to serve as bracing. The 1988’s new frame was patterned after the 1987 Suzuka 8-Hour racebike with the upper beams being thicker and splayed wider. The steering stem grew from 60 to 80mm while the swingarm pivot was now cast into the frame instead of welded on. The larger 43mm forks featured “..more adjusters than an insurance convention,” according to Cycle World’s Paul Dean. A first for a mass-produced streetbike, the forks featured adjustments for spring preload, compression and rebound damping in a time when most bikes were lucky to get forks with adjustable air pressure. The GSXR750J-model’s chassis also featured a new gas-charged rear shock, a more progressive shock linkage, a 2.0-inch shorter wheelbase, and steeper steering geometry. The highlight of the new chassis had to be the huge-for-the-day, 3.50-inch front and 4.50-inch rear 17-inch hollow-three-spoke wheels, with Michelin Hi-Sport radial tires developed specifically for the GSXR750.

The new frame cradled a new short-stroke engine. The bore/stroke went from 70×46.7mm to 73×44.8mm. The redline went to a sky-high 13,000 rpm, higher than Schwantz’s 1987 Superbike’s motor spun! Changes included a bigger airbox, a new Suzuki Condensed Air Intake (SCAI) system feeding fresh air to the airbox, bigger valves, new cams with more lift and duration, higher compression, 36mm “Slingshot” carbs (up from 34 mm), dual-electrode spark plugs, a new digital ignition, a 4-into-2 exhaust system, more oil capacity, a larger oil cooler and higher-flow oil lines for improved cooling, and it all worked to raise power to 90 horses. The new powerplant was moved 12mm lower to reduce the center of gravity. A new fairing reduced drag by a claimed 11 percent with internal streamlining to help keep the rear shock cool. The wider frame allowed the reshaped gas tank to carry the same amount of fuel, but lower. The new bike was 3.3 inches lower from the top of the fairing bubble to the ground. The result was a motorcycle that looked and felt more compact, made much more horsepower, but weighed a whopping 40 pounds more. The extra weight came from the engine (11 pounds heavier), frame (15 pounds heavier), plus the wheels, tires, and exhaust. Suzuki engineers felt that the added weight was necessary and worth it, given the much improved chassis. In fact, the extra weight actually lowered the power-to-weight ratio with the ’88 versus the ’86. Unfortunately, the new chassis had a lack of cornering clearance even at a moderate pace on the street, and it was hard to improve the engine’s power output to race levels.

The lower engine position, the new exhaust, the extra weight, the 17-inch wheels and lower- profile tires all contributed to the lack of cornering clearance. The band-aid fix was maxing out the shock’s spring preload, but this forced a compromise chassis set-up. The racer fix was to fit a 4-into-1 exhaust with a high pipe, pulling the fairing lower in tighter if not removing it altogether, and most importantly, fitting a shock with adjustable ride height. With the original long-stroke configuration, the Suzuki made decent low-end and midrange power out of the box. Race tuners quickly were able to develop the top end power that they wanted. The new, more oversquare motor came with a top-heavy powerband and little else. Unfortunately, engine builders were not able to tune the new motors to the power levels of the old long-strokers, and to make matters worse, the combustion chambers were prone to cracking and losing pieces of aluminum around the valve seats. But although he was down on power on the Daytona banking, Schwantz felt the new chassis could make up the lost time and then some through the infield and the old, short chicane. Schwantz took the Pole and won the 1988 Daytona 200 in his last AMA Superbike ride. (In the last 20 years, Suzuki has won the Daytona 200 exactly three times. In 1981, Wes Cooley rode a GS1000 to victory. In 1988, Schwantz got the job done. Mat Mladin made it three this Spring.) Also in 1988, Doug Polen won the AMA 750cc Supersport Championship, the GSXR750’s first. Polen was followed in the 1988 750cc Supersport points standings by a fleet of Team Hammer Support riders, including Scott Russell, David Sadowski, Russ Paulk, Mike Harth and Jamie James. The February 1988 issue of Cycle reported “�the new bike did everything more quickly and easily than the old: Stop, go, turn and drag the ground,” adding that the bike “�really forces a compromise between optimum suspension settings and maximum ground clearance.” For the third year, journalists complained about the racer crouch seating position and engine heat getting to the rider.

However, the GSXR750 often got better street ride rankings for its very adjustable and compliant suspension and wide seat.When I asked Steve Findley how he deals with the ground clearance problem on the 1988 GSXR750 he brought to Oak Hill for our track day, Findley said, “I put a different shock on it, but mainly I lay it over until I see sparks. That’s as far as it’s going over. It handles real well for what it is. It’s a lot of fun to go out and ride. It still makes good power. I’ve got a newer one to race, and this one to play on.” Findley regularly races his GSXR750 with the CMRA. So it was no surprise that this machine featured some race hardware including Michelin Pilot tires. After riding the 1988, Schwantz said, “It feels a little bit different than the ’86. The biggest improvement between the two is the power. This bike feels more like a racebike. It doesn’t have that plushy, streetbike-ish feel. It works well. No problems getting around out there. I think my knee even hit the ground a few times. It does remind me of the ’88 that I used to win the Daytona 200. From the ’87s to ’88s, the bikes that my teammates were racing anyway, the ’88 had a little different feel to it. It was more aerodynamic. I think that paid dividends in the 200. This bike was all pretty respectable. I wouldn’t mind racing it for a weekend.” Spies added, “It was a lot different that the ’86. It was more jacked-up in the rear, It felt good. It handled good. I was having fun on it. The higher rear end made it steer quicker than the ’86. It felt more like a modern racebike. It was probably a little heavier than the ’86, but I wouldn’t guess by much. I didn’t really feel it out there. The ’88’s power range was smoother. This bike didn’t feel that far from my racebikes.”

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Fighter pilots and motorcycle racers both talk with their hands.
Here, young gun Ben Spies confers with former World Champion Schwantz.
 

The complaints about the ’88’s ground clearance problem were so severe that Suzuki engineers reacted in the very next model, the 1989 GSXR750K. For $600 more ($5799), Suzuki engineers moved the shock’s top mount 4 mm lower and installed 6 mm longer fork tubes to relieve clearance problems. Stainless steel covers for the exhaust canisters, revised transmission gear ratios, a lower secondary gear ratio, a four-way adjustable brake lever, and a competent challenger from Kawasaki were all new for 1989. In Cycle World’s July 1989 comparison, the GSX-R was cheaper, 14 pounds lighter, slightly stronger on the brakes, had a much better suspension, and won. Kawasaki’s engine, however, produced a wider, more forgiving powerband. Kawasaki’s first shot at the GSX-R came pretty close to the mark, but then again, they had three years to take aim. The 1989 GSX-R continued to perform in the hands of racers. Jamie James won both the AMA Superbike and 750cc Supersport Championships for Yoshimura Suzuki. Doug Polen won the 1989 All Japan F1 Championship on a GSX-R as well.

From first glance, the 1990 GSXR750L-model didn’t appear to be much changed. An enthusiast might notice the new stainless 4-into-1 exhaust and the rear shock’s remote reservoir. The truth was that the bike was thoroughly revised from 1989. The frame was improved again. The main sections were splayed wider while the steering head braces, running to the front frame downtubes, were repositioned to make room for a new, larger oil cooler. A longer swingarm with thicker walls was also added, extending the wheelbase from 55.1 inches to 55.7 inches. The rear wheel grew to 5.50 inches in width and the rear tire from 160 to 170. Suzuki engineers had to lengthen the transmission output shaft by 3mm to get the chain around the new tire. The rear shock not only got the reservoir but a new aluminum body and more adjustability. The front rotors were now slotted and thicker instead of drilled and thinner. The biggest news was that Suzuki engineers had gone back to the original, long-stroke engine layout for 1990 while maintaining the short-stroker’s power and redline. Piston speed was now up to where only racing motors had dared to go before, but Suzuki engineers had learned a lot about how to make connecting rods since 1985. Now, the rod bolts threaded into the rods themselves rather than using an external (and heavier) nut and bolt arrangement. The new rods, as with many of the 1990’s parts, were carryovers from Suzuki’s limited-edition 1989 GSXR750 RR. Included in those parts were smaller, lighter pistons than in the 1986/1887 with a new Alumite coating. The combustion chamber now had a more domed shape. To help prevent cracking of the area between valves, spark plugs shrunk to 10mm. The oil cooling system was once again improved. A curved oil cooler from the GSXR1100 allowed more surface area without more frontal area, increasing heat dissipation by 48 percent. A new, deeper oil sump helped prevent windage loses. Suzuki’s 49-state GSXR750s got 38mm carbs (California models had the same 36s) with a non-functional power jet that tuners soon made functional. The new 4-into-1 pipe improved ground clearance but definitely restricted power. The $6199 1990 model made 11 percent more power than the 1986 and weighed 6.0 percent more. The GSXR750L-model weighed 494 pounds fully wet. In the hands of journalists, the 1990 GSXR750 broke into the 10-second bracket at the drag strip while topping 150 mph on a long-enough road. The GSXR750’s main competition was again the Kawasaki ZX-7, but magazines regularly tested these two against the expensive, limited-edition Honda RC30 and the non-U.S.-legal Yamaha FZR750RR/OW01. Even in this lofty company, the Suzuki usually won high praise on the street (for suspension compliance, not ergonomics) while turning the quickest time in the quarter-mile for the least amount of money. With Kawasaki inching closer, Suzuki began to stumble in 1991. The 1991GSXR750M looked very different from the outside. The all-new bodywork grabbed a lot of attention. A slimmer tailsection and headlight cover reduced drag by a claimed 2.3 percent. The Suzuki’s inverted Showa front forks were a first on any streetbike and were credited with better handling especially under braking. Another change worth noting was made inside the cylinder head. From a set-up with a single cam lobe and single forked rocker arm actuating a pair of valves, Suzuki went to individual cam lobes working individual rocker arms. The old forked rockers were now considered too massive while being too flexible at very high rpm. Valve lash went from being adjusted by heavy screws on the rocker arms to small, simple shims.

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Although he was hesitant at first, Kevin Schwantz stayed out on the
1991 GSXR750 the longest. The holes in the fairing on this example carry
projector head lamps for street riding.
 

The engineers also revised porting, installed the GSXR1100’s stiffer valve springs, reshaped the combustion chamber, and changed cam timing slightly. After all this work, Suzuki claimed no power gain, only that peak power could be held for longer with better high-rpm control of the valve timing. The ’91 did gain a few horsepower, now up to 94-ish, saw 2.0 more mph in top speed, no improvement at the drag strip with Cycle World at the controls, but more importantly gained another 20 pounds and now weighed 514 fully fueled. Where did the weight come from? The new bodywork, the new forks, the glass headlight cover, an OEM steering damper, and the reinforced frame downtubes. The Suzuki was now the heaviest bike in its class behind the Kawasaki ZX-7, ZX-7R, and the Ducati 851. Still, the Suzuki was second to only Kawasaki’s expensive limited edition ZX-7R in terms of power and quarter-mile times and won Cycle’s comparison on the strength of its street manners and lower price over the second place ZX-7R. Cycle reported, “�the least expensive bike in this test is also the most impressive,” and “�it remains the weapon of choice for the street, offering superior suspension performance, and near-parity in acceleration with the class’ hardest runner, all in the class’ best-rounded, and most accessible package.” That same ZX-7R marked an end to Suzuki’s dominance in AMA 750cc Supersport racing. Starting in 1990 through ’91 and ’92, Kawasaki’s Scott Russell and Doug Chandler went on a 26-race winning streak. Yoshimura did not even bother to field a team in 750cc Supersport in 1991 or 1992. Our 1991 test bike, an ex-endurance racer now retired to the street, was provided by CMRA racer Chuck Catlett with a motor by Tracy LeBlanc. The bike featured high compression pistons, a Fox shock, pipe, jet kit, and some shagged-looking Michelin slicks. Schwantz gave the slicks a long look before heading out onto the track.As Schwantz rode each of the bikes, the owners would just glow like proud fathers.

Catlett was no different, saying, “It’s absolutely wonderful to have Kevin Schwantz ride my bike. I didn’t realize it was so fast. He and Ben have been saying good things about the other motorcycles so far. I’m just keeping my fingers crossed that they’ll say something good about this one.” Schwantz knew that we weren’t concerned with lap times and was riding casually fast most of the day. However, Schwantz took extra time getting up to speed on the ugly tires. But once up to speed, Schwantz kept the ’91 out for the longest. The thinner-than-you-think Schwantz came in finally and said, “It’s definitely a different feel than the ’86 and ’88. It feels like you’re sitting more on top of everything. You’re not sat down into the bike as much. It’s a little bit different feel. It took me a while to get comfortable with it. All-in-all, it feels that there’s been improvement as the bikes have progressed. It feels like this bike could do more of what you wanted once you really started to ride the thing hard. It’s more of a comfortable, modern-day feel as to you sitting on top and maneuvering it a lot better. I was pretty happy. I didn’t really notice any increase in weight. Maybe it helps here at Oak Hill, a little heavier bike helps soak up those bumps a little better. Maybe that’s why I was more comfortable on it, too. Each bike has its own little things that it does good. This one feels better on the brakes than the ’88 that I rode. They didn’t have the initial bite, but they felt like they would stop you quicker more comfortably. The inverted forks could very possibly have helped the feel on the brakes. I like the suspension on this bike. The ’88 may have been a little harsh for me. I liked the feel of this bike as much as the ’86. The rear tire was a little bit greasy, though.” Spies’ comments weren’t quite as detailed. The teen said, “The ’88 and ’91 weren’t two totally different bikes. They both handled about the same. The ’91’s power came on a little lower. It didn’t hit as abrupt as the ’88’s power. The brakes I thought were about the same. This bike wasn’t farther away from the ’86, and it wasn’t much closer to my bikes. I still like my ’99 racebikes the best.” While the world got a water-cooled GSXR750 in 1992, the U.S. had to make due with bold (and I do mean bold) new graphics, an unintentional power increase to near 100, a $200 higher price at $6699, and an overweight and under powered liquid-cooled GSXR600 little brother. There had been meetings at Suzuki about a radical redesign to a twin-spar frame/downdraft carburetor layout, but the proposal was reportedly shot down by marketing guys saying that it would be a “me too” design and “it wouldn’t look like a GSX-R.” I wonder where those guys are now. In their defense, the GSX-R was still selling well. The 1993 U.S. model went through a major change. Finally, Suzuki engineers gave up their losing battle with the heat-versus-power trade-off and went to water-cooling. The results were actually less horsepower in street trim, more power in race trim with a successful return to 750cc Supersport racing, and the heaviest GSXR750 ever. Suzuki engineers didn’t just abandon their much-beloved oil cooling, though. (In fact, Suzuki has current streetbikes with engines derived from the original GSXR’s oil-cooled engine.) They retained the first stage of the oil pump that circulated oil through the engine as well as sprayed the undersides of the pistons. The rest of the cooling system was over-engineered to help racing efforts which had been hurt the most by the oil cooling system’s shortcomings. The new cooling system had twice the cooling capacity of the 1992 model’s air/oil-cooling system. Suzuki engineers worked hard to upgrade and take advantage of the cooling system. The valve train lost its rocker arms altogether now, letting the cam lobes work directly on valve buckets. The included valve angle was narrowed to 32 degrees from 40. Better heat control let the compression ratio rise to 11.8:1 from 10.9:1. The pistons got lighter, and the valve stems grew slimmer. The engine was narrowed by 57mm thanks to reduced cylinder pitch (the space between the bore centers), a shortened crank, and a new gearbox using narrower, large diameter gears riding on finer pitched shafts. The smaller engine could now be mounted lower to improve the center of gravity and front weight bias without the fear of ground clearance problems.

10

Kevin Schwantz can make any bike go fast, including the first water-cooled GSXR750.
Besides having water cooling, the 1993 model also set a record for GSXR750 weight,
weighing over 550 pounds fully fueled.
 

Once again Suzuki engineers tweaked the chassis. A new pentagonal-section frame increased rigidity 5.0 percent. A new asymmetrical swingarm was more rigid while allowing the exhaust pipe to tuck up for more ground clearance. The aluminum subframe was now removable. The steering geometry was quickened while the wheelbase was lengthened. Suzuki brochures claimed that the frame and swingarm were lighter, but the GSXR750’s weight was now 553 pounds wet, a full 100 pounds more than the original 1986 GSXR750 and the 1993 Honda CBR900RR released just a few months before! The new bike was fundamentally identical to the 1992 GSXR600 which was itself basically a de-bored 1993 GSXR750. It cost $7299 to have a water temperature gauge on a GSXR750 in 1993. Unfortunately, the Suzuki men didn’t get much in the way of results for their efforts. Power was down about 5.0 horsepower, to 95. Most tuners felt the culprit was in the cam timing. Other rumors said that there were problems with the new single-spring valve train forcing the bike to be de-tuned at the factory. Yoshimura’s tuners liked the bike just fine and returned to 750cc Supersport racing to win the 1993 AMA Championship with rider Britt Turkington’s four wins and nine podiums. AMA Superbike pilots Donald Jacks and Thomas Stevens had less fun. Stevens said, “I’ve never ridden so hard to go so slow.” In a 1993 comparison between the Yamaha YZF750SP, the Kawasaki ZX-7, and the GSXR750WP-model, Cycle World wrote, ” The Suzuki’s dyno numbers are a disappointment,” and “�liquid-cooling has not brought an increase in performance. Even with its power deficit, the GSXR wasn’t that far off the pace�” and “�on the street, its suspension was the most comfortable. The ZX is quicker, faster, better on the racetrack than the GSXR, and easier to ride at speed.” The YZF was excluded from the results because it wasn’t available in the U.S. yet.
11

Marketing concerns delayed Suzuki’s switch from the original
cradle-type frame to the twin-perimeter-spar frame introduced for 1996.
Here, Ben Spies rides a 1993 with a cradle frame while
Kevin Schwantz tries a 1999 with a spar frame.
 

Randy McSpadden’s 17,000-mile 1993 GSXR750 was one of the cleanest and closest-to-stock of all of our test bikes. The only non-standard parts were EBC brake rotors from Marietta Motorsports to replace the warped stockers. Schwantz went first and came back, choosing his words carefully, to say, “It felt the heaviest of everything I’ve ridden so far. It’s hard to get it to fall off into the corner. It wants to stay stood up. It feels like this bike, in box stock trim, you had to force the thing to make a turn. Of all the bikes thus far, this was the most difficult to ride, to try and ride quick anyway. The suspension’s nice and plush. The brakes work good. The power feels good, if not better than, everything I’ve ridden. It’s more difficult to ride because you have to manhandle the thing. It feels like the ’86, as you are sitting in it. It lost the feel and maneuverability they gained in ’91 by sitting on top. It feels more like a sport tourer, like a road bike, not something you’d want to take to the track. It would be a difficult piece to race. I think you would notice the 25 pounds they removed for 1994 in the acceleration and the handling of it. I’m not sure it doesn’t need more than 25 pounds of a diet, though.” Then the 1993 World Champion joked, “Suzuki obviously focused their efforts more on their two-stroke projects than their four-stroke projects in 1993.” After only four laps Spies came in looking pale and asked if he had ridden the 1993 enough. Spies had a hard time softening his comments for the benefit of McSpadden, saying, “That sucked! Er, um, I mean, it’s not as good as the other ones. I wouldn’t race it. You can’t turn it. It’s heavy, and it just doesn’t want to turn. I have no clue what changes Suzuki made, but you have to pull it down. If you get back up in the seat, it stands back up. It might be able to wheelie, though. I wouldn’t have been happy if I had been riding for Suzuki in 1993. Maybe when the race teams got it, they could make it pretty good. As far as a streetbike, taking it to the racetrack, I don’t think it’s that good of a bike out of the box. It might be an alright streetbike. It’s stretched out pretty good and comfortable, but it’s not the hottest thing on the track. This ranks last. It’s the worst. The ’86 handles better than this. Suzuki must have been paying all of their attention to Schwantz in Europe.”

Suzuki engineers heard the press’ cries and reacted accordingly while bigger plans developed. The $8099 1994 GSXR750SPR-model went on a diet, losing about 25 pounds via reduced frame wall thickness, new magnesium valve and engine covers, lighter brake rotors, hollowed transmission shafts, and machined transmission gears. But the GSXR’s diet didn’t preclude some new goodies. The forks grew from 41 to 43mm but with thinner walls to help the weight problem, the rear tire widened to a 180, the front brakes sprouted six-piston calipers, and the swingarm got a bridge-type brace. The engine tolerances got tighter, squeezing about 5.0 more horsepower, once again just nipping the 100 mark. In 1994, the GSXR 750 faced class competition from the Ducati 888 LTD, Honda’s RC45, the Kawasaki ZX-7, the Kawasaki ZX-7R and Yamaha’s YZF750R in the June 1994 issue of Cycle World. The GSXR was the least expensive, fastest in the quarter-mile at 10.7, tied for last in top speed at 155 mph, second-heaviest, next-to-last in braking distance, next-to-last in roll-on acceleration, third most powerful on the dyno, but next-to-last in Willow Springs lap times. But in the hands of Tom Kipp, the 1994 GSXR750 won the AMA 750cc Supersport title, the model’s fourth crown in seven years. There were no changes but a $400 price increase to $8499 for 1995. In 1993 Sportbike reported, “The original GSXR reversed an earlier cycle of weight growth. It will happen again, and perhaps Suzuki will be the instigator, or perhaps not.”

About that same time, Suzuki engineers were having a meeting that started the program that resulted in the 1996 GSXR750T-model. Marketing gimmick or truth, Suzuki engineers said that they used the size and aerodynamic shape of Kevin Schwantz’s 1993 500cc Grand Prix World Championship-winning RGV500 as a starting point for the design of the 1996 GSXR750. The new model’s twin-spar perimeter frame was twice as stiff and 5.0 pounds lighter than its predecessors! A 55.1-inch wheelbase, 24 degrees of rake, and 3.9 inches of trail were chassis numbers straight off Schwantz’s racebike. Lightweight forks, a braced swingarm, a piggyback-type shock, lighter wheels, lighter brake rotors, and a two-piece removable subframe completed the most race-ready chassis to date. Weight reduction efforts went so far as to reduce the number of fasteners used on the bike by 10 percent, saving over 2.0 pounds. Suzuki engineers claimed that with the weight reduction and horsepower increase, they had their best power-to-weight ratio ever at 3.1 pounds/horsepower. The new GSXR750 weighed 451 pounds fully wet or about the same as the 80-horsepower 1986 GSXR750. The new frame allowed for a conventional engine location, and the utilization of downdraft carburetors.

Suzuki engineers started with a clean sheet here as well. Gone were the cylinder liners and in their place were nickel-silicon-carbide-coated siamesed aluminum cylinders saving weight while reducing cylinder width and depth from front to back. Moving the cam drive to the right side reduced crank bearings from six to five, also reducing engine width. Overall, the new engine was 1.2 inches narrower. The engine’s front-to-back dimensions were reduced by a triangular arrangement of the crank and transmission shafts and a horizontally split, three-layered crankcase that allowed access to the transmission without disturbing the crank. With the new engine forward and the valve angle narrowed, the intake tract was severely straightened. Lift the hinged fuel tank, prop it up on its rod, remove the air box, shine a light down the Suzuki Electronic Enhanced Carburetion-controlled 39mm carburetors, and you could see the valves. Suzuki engineers claimed 127 crankshaft horsepower from the new, oversquare 72x46mm motor. Although readings varied widely from bike to bike, horsepower at the 6.0-inch rear wheel with 190-section tire ranged from 110 to 118 with 110-112 being typical. But some of those 118-horse engines didn’t last long. Either the engine blew or was slightly detuned with a thicker head gasket when Suzuki recalled the GSXR750T for inadequate piston-to-valve clearance. Of course, all the horsepower numbers were recorded without the benefit of the very effective Suzuki Ram Air Direct (SRAD) system.

Everything was wrapped in lightweight, aerodynamic bodywork with a distinctive anti-draft tail section. Suzuki then blew everyone away by offering this incredible new package for only $8999. Yoshimura’s Aaron Yates and Pascal Picotte blew everyone away in AMA 750cc Supersport competition, also. Yates made it five titles in nine years for the GSXR750. What a difference a couple of years can make. In May ’96, Cycle World had an “Ultimate Sportbike Challenge” comparing the new GSXR with Kawasaki’s all-new ZX-7R, Yamaha’s YZF750R, Honda’s CBR900RR, and Ducati’s 916. Once again the GSXR cost the least, but now it also weighed the least, had the fastest top speed, went quickest at the dragstrip, was best on the brakes, second-fastest at Willow Springs by 0.02 second to the Ducati, and third in roll-on acceleration. Kawasaki’s new bike was close to the new GSXR750 in power but weighed 65 pounds more. Due to the rule structure in AMA 750cc Supersport, Muzzy Kawasaki felt that the ZX-7R was so uncompetitive that the team withdrew from the class mid-season. The 1996 GSXR750 made 750cc Production/Superstock/Supersport classes everywhere a Suzuki spec-class from 1996 to present. Cycle World called it , “�the Suzuki GSXR750, the closest thing yet to a street-legal GP bike.” Motorcycle Consumer News wrote, “�open-bike power, middleweight handling and superb attention to detail, it’s really in a league of its own, and the unquestionable winner here.” Racetracks became infested with the new GSXR750.

As a streetbike, the new Suzuki was actually one of the more ergonomically comfortable GSXR models. A lack of midrange power hurt the Suzuki’s street performance slightly, or at least was the only nit to pick. The GSXR became the V-model at $9199 and unchanged for ’97 except for the birth of its little brother, the GSXR600. Jason Pridmore won the AMA 750cc Supersport title for Hyper Cycle that year while Peter Goddard and Doug Polen took the World Endurance Championship including 24-hour wins at Le Mans and Spa. This was the GSXR750’s sixth AMA Supersport and third Endurance World Championship. At the press intro of the 1998 GSXR750 at Road Atlanta, Suzuki’s Press Relations Manager Mark Reese said, “We’re at a point on high performance models where we’ve basically reached a limit with carburetors and emissions requirements.” Suzuki added a fuel injection system featuring the same Mikuni injectors, Denso engine control module (ECM), and sensors as the 1997 TL1000S, with a single injector per cylinder and 46mm throttle bodies. The factory aimed for a 5-horsepower gain and most dynos showed the new power output to be around 115. Other changes included cams with more lift and duration. Exhaust revisions and a flapper valve in the airbox were aimed at improving the midrange. The fuel injection system and associated electronics added weight, but weight savings came from reducing the primary drive gear width by 1mm, the #530 chain to a #525, “narrow waist” crankcase bolts, and individual coil/spark plug caps. Weight still grew by 8.0 pounds, to about 459. Brake rotors grew in thickness to help racers who had to replace the thinner ones nearly every race weekend. The rear shock’s link mount was strengthened. A non-adjustable steering damper was added.

The 1998 bike also got revised spring rates and damping. The rear shock got a further improvement thanks to knowledge borrowed, once again, from Suzuki’s RM. A metering rod expanded and progressively restricted a damping orifice to maintain damping characteristics as the shock heated and the oil thinned. The biggest complaint about the new GSXR750 concerned the abrupt off-on throttle response of the fuel injection system. Aftermarket companies provided command modules that could be plugged in to alter the computer’s fuel and ignition mapping to tune out the off-on throttle problem and to tune in a new exhaust system. Richard Alexander won the 1998 AMA 750cc Supersport title in the last race of the season over Steve Rapp. The GSXR750 got bold new graphics for 1999 and its eighth AMA 750cc Supersport Championship in 12 years from Chaparral’s Tom Kipp. Since the 1996-1999 GSXR750 had no true 750cc peers, magazines started comparing the bike against bigger machines. Cycle World pitted the 1998 GSXR750 versus the Kawasaki ZX-9R, the Honda CBR900RR, and Yamaha’s YZF-R1 in April, 1998. CW reported, “�are far as modern sportbikes are concerned, the trend began in 1985 with the revolutionary aluminum-framed Suzuki GSXR750,” and “All of a sudden, the GSXR feels kinda uncomfortable on the street, kinda heavy-handling on the racetrack and seriously hurting for midrange power.” From the same test, Mark Cernicky commented, “�the fuel injection on the new bike is terrible. It surges at steady rpm, and has an on/off feeling exiting slow corners that makes you feel jerky even when you’re being as smooth as possible.” Nick Ienatsch added, “I don’t like the steering damper’s effect on slow-speed handling.”

The GSXR750 still was quicker and faster than the CBR900RR while being within 0.3-second and 5.0 mph of the other bikes and cost about $800 less. For our test we had arranged both a 1996 and a 1999. Unfortunately, our 1996 didn’t make it. Since the 1996 through 1999 are nearly identical chassis-wise, we just jumped to our 1999 brought by Scott Crawford. You would think a man like Crawford, who qualified fifth-fastest in the 1999 600cc Suzuki Cup Finals, would have a heavily modified street ride but just the opposite is true. Crawford got the bike we tested from a friend who needed money bad, for just $900. Crawford picked the crashed bike up off the ground, replaced the destroyed stock canister with an aftermarket slip-on, spooned on some Dunlop D207 GP tires and started riding it to work. After riding the 1999 immediately after the 1993, Schwantz said, “It’s night and day! Just talking to some of the guys around here, I think Suzuki concentrated on what a streetbike (comfort, cush, plushness) needed to be in ’93. Because it definitely doesn’t work around the racetrack. Of course it’s stock, and I’m sure you could make some adjustments, stiffen everything up a little bit, put a bit more ride height in the rear, and maybe make the thing handle better. It takes an effort. You’ve got to take the thing into a corner, and then you’ve got to hold it down. Not a lot of fun to ride around a tough, bumpy, tight racetrack like Oak Hill. The ’99 is a night-and-day difference. It does everything really good. It turns in. It stops. It finishes the corners. Even some of the early production stuff, the ’86 and ’88, didn’t have the power to finish the corner. The ’99 does everything well.” Spies said, “The bike has a lot of power. I was surprised. (Crawford) says there’s not much done to it, but it runs real good. I think this overall deal is a really good package. It handles good, and it’s got plenty of power. It handles better than any stock suspension bike that I’ve been on. It wasn’t dancing and bouncing around. It was pretty planted for it being bone stock. This is pretty much identical to my bike except it has 150 more cc, but it turns in and handles a lot like the ’88. The ’86 you sat way down low in it. This one you’re up high like a racebike.”

Then we asked Spies to re-think his early response that the ’88 and ’91 were pretty close to his modern racebikes, and Spies said, “Yeah, they’re still pretty close except for the power and the way they look and all.” Crawford, who knows Spies from CMRA racing, heard this and joked, “I think Ben had too long of a lunch break. I had a bunch of those old ones, and they’re nothing compared to the new ones. The ’96 had it all over the old ones, and the fuel injection just makes it that much better.” During the owners’ riding sessions, Crawford looked so fast that Schwantz asked for a stopwatch to put on him. We also asked Schwantz about the resemblance (Suzuki claimed) between his RGV500 and the ’96-and-up models. Schwantz said, “I see it to a certain extent. It feels like my bike was a lot more nimble than these bikes obviously. The ’99 wants to do things that the Grand Prix bike did in ’93 when we won the World Championship. It doesn’t feel like it does anything really wrong. It stops, it turns, it lets you get the thing on its side, it lets you get back if you miss the apex of some corners, in all it’s a pretty forgiving motorcycle similar to the GP bike. And it’s real adjustable, allowing it to work at a lot of different racetracks. The ’99 gives you a real confident feel. It’s real balanced and a lot of fun to ride.” Some may say that the GSXR750 has no competition and ask, “Why bother to change it?” Although the 1996-1999 GSXR750s have cornered the market on most racetracks and in 750cc sales numbers, the fact is that Suzuki built this machine for the same purpose today as they did in 1986-to win National and World Superbike races. In those categories, the GSXR750 has a lot of competition especially from all of the V-Twins. Even though Pier Francesco Chili put the GSXR750 on top of the box a few times in 1999 World Superbike competition and Mladin won the 1999 U.S. Superbike Championship, for 2000 Suzuki engineers again remade the GSXR750 while keeping the price at $9399. The Suzuki men shaved every gram of weight off of the new model while making it smaller, better handling, and more powerful for street riders and racers. Although it looks about the same, the frame of the 2000 model is all-new. The 4.0-pound-lighter frame is smaller to carry the 4mm-shorter (top-to-bottom), 8mm-narrower, 15mm-shorter (front-to-rear), and 11-pounds lighter engine. The swingarm lost 800 grams while being lengthened. The swingarm grew 20mm while increasing the wheelbase only 15mm thanks to the shorter engine. To keep the quick steering, the rear wheel was reduced to 5.50-inches, carrying a 180 tire while the front end geometry stayed the same. Front weight bias has gone from 50/50 to 51.4 percent front/ 48.6 percent rear. The front brake rotors are lighter with four-piston calipers (with aluminum pistons) replacing the six-piston calipers used since 1994. Lighter wheels, bodywork, shock, and forks complete a chassis that is 18 pounds lighter than the 1999 model’s.

12

The 2000 GSXR750’s perimeter-twin-spar frame,
made in the image of 500cc racebikes.
 

The 2000 GSXR750, at 428 pounds fully fueled, now weighs less than the original 1986 model. Weight was removed from the engine by lightening the rods, crank, valve springs, cams, alternator, head casting, and wrist pins. Now the Suzuki’s cylinder is cast as one piece with the upper crankcases, saving weight and adding strength. Suzuki engineers also eliminated external oil lines, routing the oil through passageways cast inside the cases and head. But the biggest improvement to the engine, and the entire bike for that matter, comes in the form of the revised fuel injection system. Anyone riding the two bikes back-to-back can feel the difference. Suzuki engineer Kunio Arase developed a fuel injection system that works like a digital CV carburetor, using a second set of butterfly valves controlled by a more-powerful ECU. While the rider opens the primary throttle butterfly valves with the twist grip, the ECU opens the secondary throttle primary valves progressively to maintain intake velocity. The result is the elimination of the off/on throttle abruptness, exponentially increased midrange, and a measured 126.6 rear-wheel horsepower on a Dynojet Model 200 dyno, in the hands of Roadracing World.

13

The 2000 GSXR750 engine. It’s water-cooled and is lighter and smaller
in every external dimension when compared to the original GSXR750 engine.
It also makes a lot more horsepower.
 

Normally racers get access to their bikes before they are in showrooms to make the early season races. Word is that Suzuki purposely prevented this in 2000 because the new bike, out of the box, is better than most developed 1999 racebikes and would therefore give an advantage. Schwantz said that he could take a stock 2000 GSXR750 with all of the street gear (including lights, turn signals, mirrors and standard tires) and beat his pole position time from the 1988 Daytona 200, which was 1:55.1 running the slower, short chicane. Schwantz had ridden a 2000 GSXR750 a few times before arriving at Oak Hill but was still impressed after lapping Oak Hil. ” It’s amazing what a good production bike can do as far as getting that enthusiasm, going out and riding, and having fun,” Schwantz said. “I just get a little more used to it every lap. Of all of the riding we’ve done today from the ’86 to the ’88, the ’91, the ’93, the ’99, I think they’ve picked up all of the good traits, as little as they may be, of all of the GSXRs and got them maybe all in one package. It’s a really fun bike to ride. Also consider the fact that I haven’t been on a production bike in�forever. It’s a fun bike to even ride slow. Then you can progress to getting faster and faster on it. It stayed as much fun to ride, and it still did everything good from slow to, well, not top-level competition, but respectable times for an old man anyway. The suspension works great. If I were gonna race it regularly, I’d probably make an adjustment here and there. Straight out of the box, it’s still a remarkable bike to ride.”

14

Ben Spies leads on the 1986 GSXR750 while
Kevin Schwantz watches from the seat of the 2000 GSXR750.
 

I must say that, (and I think that I speak for everyone in attendance at Oak Hill that day because they all stopped what they were doing to come watch with many cameras rolling), that it was worth everything it took to make this test happen just to watch Schwantz ride hard laps on the new GSXR750. We knew he was riding hard because he ran off the track twice. Schwantz explained, “Just going in, getting in a little hot, and going to use a little rear brake, just set the back end off hopping. Maybe backing it in was the answer to the problem. Both times it gave a good kick, and I had to get off of the front brake to get the thing back in line. It caused me to go in the grass a couple of different times. Hey, you’ll never find where the limit is unless you keep trying harder and harder.” Roadracing World was also doing a big-bike comparison with Michael Martin, Mark Junge and Grant Lopez on race tires that same day at Oak Hill. Schwantz’s fastest lap on the 2000 GSXR on street tires without one single adjustment was only beat by two of those men, and one of those only beat the time on one of his laps. After riding what will soon be his new racebike, Spies said, “The new bike is unbelievable! It handles so good. It only had street tires on it today, but it worked well enough that you could get on the gas and see how it did. It has so much power for a production bike. Suzuki really nailed it on this one. (Comparing the ’99 to the ’00) The 2000 definitely has more power, but you can’t even compare the handling. The 2000’s that good. You have to be careful getting on the throttle because it’s real jumpy. Other than that, it’s a perfect bike. The brakes are awesome on it. Compared to the 1986, it has changed a lot! The biggest differences are probably the carburetion, the handling, and the suspension. Of course, they changed the frame and geometry and all, but that’s scientific stuff. But the ’86 was a good bike.” Spies then borrowed his mom’s cell phone to call Valvoline EMGO Suzuki teammate John Hopkins, to tell him about the new bike. This article took months of preparation and too many hours of research to count. Through the effort, I learned a lot about the incredible evolution of the Suzuki GSXR750 model line. I hope that I have been able to do justice to a truly historic motorcycle. I also hope that in 15 years we can do it all over again with Schwantz, Spies, the next rising star, and the 2015 GSXR750. How much better will that Suzuki be?

Discuss this article here.

 

 

 

 

 

 

Fitting a 916-style Steering Damper

By Banoffee.

My slabby has a lively front end, so I’ve been wanting to fit a steering damper for ages. I even acquired the period Daytona fitting kit and damper however couldn’t get that to work with my USD front end. So, seeing as I wasn’t keen on modifying the frame to take a bolt-on side mounted damper the only option left was a 916-style fitment. Seeing as I’m running an Ohlins rear shock, the damper had to be Ohlins to match of course!

Basic theory:
Whilst steering damper manufacturers don’t list fitting kits for oldskool bikes, it’s actually a simple matter of taking the measurements and then doing some research to find a suitable kit (or parts from several kits).

The measurements: (Note – some measurements are taken with internal vernier edges, some external. These are just shown to illustrate, you should of course check your own measurements carefully!)

A: Yoke nut centre to tank front mount centre

AB: Top of tank mount to top of top yoke

BC: Between centre of tank front mount bolts

CD: Between LH lock and centre (then multiplied by 2)

DThe research:
I took a tape measure with me to bike meets, bike shops etc to measure up more modern bikes (with owners permissions of course when they were about!) and also bothered a few people selling kits on ‘that auction site’.

My bike:
(750G with 400gk76a USD front end)
A: approx 50mm
B: approx 60mm
C: approx 50mm
D: approx 60mm

Things to note:
On my slabby, the damper is quite close (5-10mm) to the tank. Double, triple check all measurements to ensure it won’t foul anwwhere.
Source the fitting kit before buying a damper so that you can mock up and modify if necessary. Setting a good search on ‘that auction site’ makes this surprisingly easy and cost-effective.
For the damper stroke, obviously err on the side of slightly longer but not too long as it will look unbalanced.

The result:
I picked up a 2000-model H*nda Firebl*de Harris fitting kit from ‘that auction site’ for a whopping �20. Measurements were near-perfect as a 1-2mm on the tank mount, etc. is just fine. Only slight drawback was 30mm lower ‘B measurement’ so I acquired a 30mm tubular spacer.

EMy ‘D measurement’ (remember to multiply by 2 of course!) meant an approx 60mm stroke damper so I ordered a 63mm stroke Ohlins damper from BikeStuff (cheers Rich!).
In the pics below you can see the finished result. I’ve lost a tiny amount of right-lock, however, eventually I’ll get a spacer made up to under the tank-mount part which will solve that. All-in-all I’m well pleased!

245

Frankenstein’s guide to oil cooled engines

Before anything, I would like to have it said that I wrote this in my best knowledge and do
not want to be held responsible for any mistakes. I’m confident about what I’ve seen and done,
but since I’m not the only one messing around with gixxers, I can hardly ever be sure that
the engine I find in a 89 1100R is really an 89 1100R. I’ve left the types before 88 out,
since I have not much experience with them.

Frankenstein@robbynitroz.nl

There are mainly 2 types of 750’s, the 88-89 short stroke, and the pre-88 and 90-91 long stroke.
(The 750F is basicly the same motor as the 88-89 short stroke, the B6 and GSXF600 are basicly
the same as 90 long stroke with a smaller bore).
1100R motors from 88-92 are similar to the 1100F and B12 motors. The 1100G is also similar,
but has an axle drive. They all have the same stroke, and only the B12 has a 1mm bigger bore.

Apart from the color, all the GSXR, GSXF, GSXG and Bandit ignition covers are the same (except
the 750RK).

The clutch covers are depending on the clutch operation, there are 3 possibilities:
(The dry clutch is left out, to avoid making it more confusing).
1.The GSXF600, GSXF750 and B6 have the clutch cable connected to a mechanism on the sprocket
cover, and the clutch is operated by a push pin through the primary gear box shaft.
2.The 750R has the clutch mechanism in the clutch cover (on the right side). The 88-89 clutch
cover is recognizable by a smooth clutch cover, the 90-91 has a bubble in the center. They are
very similar, but since the engines have a different clutch, I don’t think these covers can be
swapped, I haven’t tried though.
3.The 1127’s and B12 all have the clutch mechanism on the sprocket cover, like the 600’s and
the 750F, but then hydraulically operated. The mechanisms on the sprocket cover can all be
swapped, so it’s possible to put a cable operation from a B6, F6 or F750 on an 1127 (and v.v.),
although it might need some adjustment of the length of the pushrod.
This also means that, since the clutch covers on the 600’s, 750F and 1127’s are nothing but
covers, they can be swapped.

The startermotor covers from the 1127’s are all the same (The startermotor covers from the 1052
engines are not the same) The 1127 covers can be recognized by a kind of bubble, to accomodate
the bigger starter motor. The 600′ and 750’s have a smaller starter motor, and the top line of
these covers is straight. (I believe the 1052 motors also have this smaller starter motor and
cover). Covers can be swapped among the 600’s and 750’s, but an 1127 cover only fits an 1127.

The oil pan on all 1127’s are the same, but the B12 is different. The 750F and 750R 88-89 have
the same oil pan as the 1127’s. The 91-750R and B6 have a similar or same oil pan as the B12,
I’m not sure. However, it is possible to swap these oil pans, as long is you change the oil
pickup as well. Oil hoses on the 1127 pans connect at the front, the others at the bottom.

The valve covers are different depending on the cam chain type, and the cylinder head size.
The B6 cover only fits the B6, the B12 cover only fits the B12. The 750R-90 and 91 covers
are the same. All the 1127 and the 750R-88/89 cam covers are the same.

There a 3 main items which make the difference in crankshafts.
1. Stroke
2. Clutch gear
3. Camchain type

1. The 1127’s and B12 all have the same stroke. The 600’s and 90-91 750R’s have the same
stroke. The 88-89 750’s and the 750F have the same stroke.
The stroke is important because this directly reflects on the number on teeth on the
clutch gear (ie. the gear diameter).
2. All GSXR1127 crankshafts are the same. The GSXF and G have a helical
cut gear, so when using a GSXF1127 crank You will have to use a GSXF1127 clutch basket as well.
3. All GSXR’s (both 750 and 1127) have the same type camchain, but the B6 and B12 are
different. Since the cam chain is driven from the crankshaft, this means these crankshafts
are not interchangeable with GSXR crankshafts, unless you also change the cam chain, tensioner,
guides, cam sprockets, cam covers, cam guiding between cam shafts.

All the 3 items above have to match. Swapping a crankshaft with a type that has the same
stroke, clutch gear and cam chain is no problem. If you start mixing, you have to match
clutch to the crankshaft (and in some cases gearbox), or cam chain stuff to the crankshaft.

Connecting rods from B6, 750R-90 and 750R-91 can be swapped. 1127 rods are all the same.
I have used B12 rods in 1127’s; I found there was a minor weight difference, but they could
easily be matched. This difference might have been incidental.

I left out the dry clutches on purpose, since I have no experience with them.

The GSXR1127 89-on and B12 have a diaphragm spring, the GSXF/G have normal springs.
The GSXR and B12 have a straight cut gear, the GSXF/G have a helical cut gear.
Because of the different gear on the clutch basket, the clutch basket is not swappable.
Since the types with a diaphragm spring have a longer shaft to accommodate the bolt for the
central spring, these parts are also not swappable. It is possible to use the internal clutch
parts from a ‘normal spring type’ in the basket (or actually on the gear box shaft) from a
‘diaphragm spring type’, but you need to fill the space on the longer shaft. It is not
possible to use the diaphragm style clutch on a GSXF gear box shaft, since the shaft is to short.

The 88-89 750R have a large (actually the largest) diameter but relatively flat clutch.
Although the gear box shaft is the same, the 88-89 clutch can not be swapped with the 91
clutch because the crankshaft diameter (and consequently tooth count) is different.
Although the B6 clutch is the same diameter as the 91 750R clutch (since they have the
same stroke), there is not a lot to swap there since the plates are different and the
gear box shaft are differently machined.

Cylinders block with pistons from 1127’s can all be swapped. B12 block+pistons fit the 1127
as well, or only pistons+have your 1127 block bored.
88-89 750’s is same as GSXF750.
B6 and 90/91 750R have 18mm wrist pins, whereas 88-89 750R, GSXF750, 1127’s and B12 have
20mm pins.
Since the B6 and later 750R 90-91 have the same stroke, cylinder block dimension, and wrist pin
diameter, the 90/91 block+pistons can be swapped with the B6 stuff (although you’ll have to
check that the pistons don’t hit the head/valves).

The long stroke engines (ie. B6, GSXF600, 90/91 750R) have the same dimensions, just the
combustion chamber and valves in the 750’s is bigger. So somebody who want less power could
fit a B6 top on a 90 750R. Camshaft type on the B6, GSXF600 and 90 750R is forked rocker,
meaning 1 cam for each pair of valves. 91 750R has shim type with 1 cam for each valve.
If swapping the camshafts as well, the 90 and 91 heads can be interchanged.
Both the 90 and 91 750R top ends can be used on a B6, but since the B6 has another type of
camchain, it is needed to maintain the B6 cam chain tensioner, guides, cam sprockets, valve
cover etc.

The 750 short stroke engines 88/89 heads have the same outside dimensions as the 1127/B12,
but the combustion chamber is smaller (although the valves are the same diameter).
The 1127R-91/92 has the same style head as the 750R-91, but
not much to swap; 1100 valve spacing differs (so camshafts can not be swapped), 1100 valves
are bigger, outside head dimensions differ.
As mentioned, 750R-88/89 valves are the same as 1127/B12, exception are the 1127R-91/92 valves.
These heads have shim type adjustment, and therefore different cams and longer valves.

It is possible to modify a 1127 shim head to a forked rocker head. It’s quite some work, and
you’ll need the valves from the forked rocker head, the rockers, cam shafts. You’ll need to
make all the spacers yourself, or in fact I believe there is a company that has or used to
have a modification kit.

Cam shafts from the 1127F, 750F, 90-750R, B6, B12, 88/89 750R are theoretically all swappable,
but of course the profiles are different. The long stroke 750’s have a different tooth count
on the cam sprockets so they can not be mixed. B12 sprockets can only be used in the B12.
B6 sprockets can only be used in the B6. 1127F and 1127R sprockets are the same, 88/89-750R
sprockets are similar, but the timing marks are different. (Meaning they can only be used if
slotted and timed)

1127: Depending on the clutch type there are long and short shafts. Also the gears themsleves
from these boxes are different. It may be possible to swap a few gears between these boxes,
but the gearchanges might not be very smooth.
Apart from the clutch type, the 91-92 1127R has a double row bearing on the output shaft, and
therefore a slightly different crankcase (around the bearing area).

Gear boxes from all 750’s are swapable. I have no experience with swapping gears seperately.

The B6 has a different shaft, so it can only be used with it’s own clutch.

Although it might seem there are so many differences, a lot can be mixed, as long as the right
parts are choosen, a few examples.
(There are some basic guidelines to assemble an engine, like check compression, cam timing, valve
clearance etc., no matter what combo you’re making).

1. A 1052 crank fits in 88-89 750R and 750F cases, but a 1127 crank doesn’t (but the cases can
be modified to take the 1127 crank as well)

2. A 750R-90 or 750R-91 top end on a B6.
It’s actually very easy, and I think all the info you need is above. Both engines have the same
stroke, same wrist pin diameter. Theoretically, it would be possible to put only 750 cylinders
and pistons on a B6. However, the pistons are designed to fit the 750 head and since that also
fits, why not install a 750 head as well (with bigger valves). Since the B6 has another cam chain
the B6 cam chain tensioner, cam sprockets, cam chain guides and B6 valve cover need to be
used. Then there are 2 options: either go for a 750R-90 top end, which uses forked rockers
like the B6 does (so it’s possible to use either the B6 cams or the 750R cams), or go for a
750R-91 top end, which uses another type of rockers so it is not possible to keep the B6 camshafts.

3. A 750R-88/89 top end on a 750R 90/91 bottom end (or 86-87 bottom).
This is a bit more difficult, since it needs some more work and imagination then the plain
assembling of a B6/750.
The 750R-88/89 have a bigger bore, so the idea of this combo is to increase the capacity of the
engine. (You could also take this combo the ‘other way around’, and fit a 90/91 crankshaft + clutch
in a 88/89 engine.)
Since the dimensions of the heads are not the same, it is not possible to only put the 88/89 pistons
+cylinders on the 90/91; the head of the 90/91 would not fit the cylinder block. So the complete
88/89 top has to be installed on the 90/91. The wrist pins on the 90/91 are 18mm, on the 88/89 20mm,
so the small end of the 90/91 rods have to be bored to 20mm. Now the whole thing could mechanically be
assembled, but since the stroke of the 88/89 is smaller, the height of the cylinder block is smaller.
This has to be compensated by putting a spacer under the cylinderblock. (This spacer would very
roughly have to be 1/2 x the difference in stroke, but the only right way is to measure/calculate the
compression.

4. 750R 6 box in a 1127 motor
The only hard thing here is to have a hole drilled through the gear box shaft, for the pushrod.
The 750 6 boxes have a single row bearing on the output shaft, and the clutch does
not have a diaphragm spring. So the easiest 1127 engines to put a 6 box in are the ones with a
single row bearing on the output shaft, and no diaphragm clutch, ie. only the GSXF1127 engines.
In these engines the 6 box drops straight in, only the shaft has to be drilled.
Second easy would be an 1127R engine with a diaphragm clutch, but no double row bearing (88-90).
In this case the box would still drop in, but for the clutch one would have to use the inner
clutch parts from a GSXF1127 (with normal springs) and the outer clutch basket from the 1127R
(with a straight cut gear, not helical).
Most work is in a 91/92 1127R where one would have to match the clutch as above + find a
solution for the double row bearing (the solution is actually to turn the double row bearing
inside out, and make a little hole for the small pin).
Of course the shift drum and forks from the 6 box have to be used as well, but they drop in
any 1127 without problems.

5. 88-89 750R head or 750F head on a 1127 or B12
These heads fit as they are, and give higher compression, better ports, larger squish.
In the case of the 91-92 1127R you’ll need to use the 750 camshafts as well, since the
91-92 1127R uses shim type camshafts and the 750 head is forked rocker type. If you use the
91-92 1127R cam shaft sprockets they can be timed as in the manual.
In the B12’s case you could use the B12 or the 750 cams (although they have different profiles)
but will have to use the B12 cam shaft sprockets because of the different cam chain.
In the case of the 88-90 1127R you can use the 750 or 1127 cams, and use the 1127 cam sprockets
(timing ‘by the book’) or use 750 cam sprockets (timing to be done by yourself)

 

How-to fitting 3.5 GSXR front wheel into EF front end

Capitan Chaos site moderator, motorcycle mechanic and EFE addict shares some useful info on upgrading the front wheel on your EFE.

Here’s how:

– remove the bearings from the EFE front wheel, and take the tube which is in between them. Do the same with the GSX-R one.
– you will find out the EFE one is 16mm longer than the GSX-R one. It needs shortening 16mm.
– buy some bearings which fit in the GSX-R wheel and on the EFE spindle. I don’t remember exactly the sizes, but you need bearings with the ID of the EFE ones, and the OD and width of the GSX-R ones. They were off the shelf in the local bearings shop.
– the tubes in the bottoms of the EFE forks are now too short. Make some new ones which are 8mm (each) longer.
– the EFE speedo drive will fit after a little bit of material has been removed. Offer it up on the GSX-R wheel and you’ll see exactly where.

And now, with that nice 3-spoke wheel, it would be a shame not to upgrade the brakes as well.
The Slingshot Nissin 4-pots, and the later GSX-R models’ Tokico 4- and 6-pots all fit on the EFE forks, 90mm spacing between the bolts. But the Slingshot discs are too large.
Now Suzuki had thought about this and launched the GSX600F in the late eighties, this bike has brake discs that fit perfectly on the GSX-R wheel and are small enough to accept the more modern calipers when mounted in the EFE forks. All it needs is some small rings to space out the calipers a bit towards eachother.
Use the EFE caliper mounting bolts, they are longer than the GSX-R ones.

Captain Chaos

Discuss here

GSX-R engine mounts for GSX frames

Below are drawings of engine mounts to fit an early air-cooled GSX (round frame tubes) or EFE (square frame tubes) with a GSX-R engine. Both place the engine in the middle which is aesthetically best but may cause some problems with the exhaust headers interfering with the frame downtubes, which can be solved by using spacers or modifying the headers if necessary.
Engine mountsEnginemounts1 for a GSX1100 frame to take a GSX-R engine.
By “jonboy”

 

 

 

A Katana with the above engine mounts installed…

katanagsxr3

 

 

 

 

 

 

 

Engine mounts for a GSX1100EFE (GS1150) to take a GSX-R engine.
By “GJG”

Below are drawings from the engine mounts, as I used them a few years back. I built at least two EFE’s using these plates. They mount the engine pretty straightforward, like in the Katana I send you pics from a few months back. I also included the cutting contours in .dxf format, that could straight be fed into a laser.

Parts description:
PL-105 and 106: Take front rubber engine mount, and lower below crank. Need shims or bushes to compensate for offset.

PL-107 and 108: These should be welded in with the engine or cases in place, mounted with the previous mentioned plates. PL-108 is a bit long, and could do with a brace, taking sideward loads to the cross tube from the shock. The stock plate should be removed. The lower cross tube in the frame will need some cleaning up and removing of the stock lower rear plates, before taking PL-107.

PL-110 and 111: These make the removable, welded upper rear engine mount taking loads to the stock bolt holes/bushings welded into the side of the frame.

GSX1100 Laser drawings

How to repair cracked engine covers

How to repair cracked engine covers.

First you remove the cover from the bike ofcourse, and then you degrease it very thoroughly.

As with all cracks in every material you need to drill small holes at the end of the cracks. Do not drill exactly at the point where the visible crack stops because underneath the surface the crack already had gone further. So plot an imaginative line in the extent of the crack and drill the hole along that line a few millimeters from the end of the visible crack.

I used a Dremel tool, but you can use a normal drill with a grinding stone (though due to it’s weight it’s harder to control) to dig a trench along the crack.
Dig as deep until you’re almost coming trough on the other side. This will make it very easy to fill it with epoxy.

Clean the other (in)side using emery paper or a Dremel tool to make sure the epoxy will attach itself well.

Then you clean and degrease the cover very thoroughly and warm it up by laying it on a heat source like a radiator or geyser.

While the case is heating up we prepare the metal epoxy. I use “Bison” metal epoxy but I guess any well known brand metal epoxy will do just fine. Just follow the instructions that came with it carefully and be sure to mix it very thoroughly. As with all two-component substances mixing it thoroughly is most important, so don’t rush it!

When the epoxy is ready apply it to the cover. Make sure you push the cracks full of epoxy so no air bubbles are left in them. If you dug them out deep enough epoxy will come out on the others side.
Your cover will have a very large flat spot so be sure to apply enough material, better too much than too little.
Apply some epoxy to the inside too but it hasn’t have to be much, just enough to make it smooth.

Then you leave it to dry on a heat source, at least for 12h untill the epoxy has become very hard. It hasn’t got the same mechanical properties as aluminium though, more like a hard plastic.

Now you can file/sand it into shape and spray paint the cover (you didn’t intend to polish it, now would ya? 😉

Well, there you are… a good as new engine cover, ready to last untill the next crash!

1. Drill holes at the end of the cracks and dig the cracks out

2. Clean the inside of the cracks

3. Warm up the cover

4. Prepare the epoxy

5. Apply epoxy liberally

6. Epoxy on the inside

7. Let it dry for at least 12 hours.