If you like to play Gran Turismo or Forza Motorsport, you’ll know the Tsukuba circuit. It’s hugely popular with the street tuner guys, who use it for ‘time attack’ sprints—and it’s also home to some of Japan’s biggest motorcycle races, second only to the Suzuka 8 Hours.
In May and November every year, the circuit hosts the famous ‘Taste of Tsukuba’ races. These are open to classic race bikes, and the array of the machinery lined up on the grid is mouthwatering. And when racing restarts in Japan later this year, one of the bikes on the grid will be this freshly built Suzuki GS1200SS.
It’ll be piloted by American Jason Fullington, an old friend of Bike EXIF since the days when he worked at ICON Motosports in Portland, Oregon. For the past ten years he’s lived in Japan, and spends his weekdays running the importer AFG Motosports. At nights and weekends, he’s testing road bikes for global magazines, building race bikes for himself, and hitting the local tracks.
Jason’s latest track weapon is this GS1200SS, which is configured to run in the Formula Zero class at Tsukuba. That means it’s a very cool mix of old and new tech, and right up our street.
“There is some modern technology, but Taste of Tsukuba bikes are mostly ‘historical’ machines,” Jason tells us. “If you are a motorcycle lover of the old school, this event is the absolute best in Japan. The races draw in celebrity riders from around the world, including greats from WSBK and MotoGP.”
With 100 horsepower on tap and a dry weight of around 460 pounds, the stock GS1200S is an excellent choice for a fun track bike. “It took me several years to master the Tsukuba circuit on my Aprilia RSV4RF, so I was ready for T.O.T. battle,” says Jason. “But finding a spec T.O.T. machine for sale is almost impossible. So you must make one from scratch, and the older bikes in Japan have a price premium.”
Then Jason had a stroke of luck. At the circuit, he met local riding legend Hiroyuki Funaki, who owned a GS1200SS modeled to look like the Suzuka 8 Hours GS1000s from years past. “I told him how much I loved that bike. Then the following day Funaki-san messaged me, and said, ‘Do you want it?’ My jaw hit the floor.”
Jason picked up the Suzuki the next day. And because the May T.O.T. race was cancelled due to COVID19, he had time to turn the GS1200SS into the ultimate retro race bike. “I wanted to give it the most top-level spec possible. I had the time, industry friends, and a chief mechanic all at the ready.”
Jason has installed new bodywork from Katana Kaji and Magical Racing, based on his dream bike: the late 80s Suzuki GSX-R750RK limited edition. “The layout for the paint and graphics was done by Icon Motosports’ ace designer Kerry Miller. I also have two sets of practice fairings, which have paint mimicking the red, white and black Suzuka 8 Hours Yoshimura GS1000.” The neat seat pad came from the Italian specialist RaceSeats.
Starting from the front, Jason sourced a set of forged JB-Power Magtan rims from Bito. The suspension has been upgraded too, using new internals installed by Junpei Ohba of S&E Precision—a world-class Öhlins suspension engineer.
For braking, Jason has chosen the highest pedigree of racing-specific Brembo kit, without compromising the nostalgic look of the bike. It’s hooked up via Stäubli quick disconnects and custom-made HEL brake lines, which flow the stopping juices from a Brembo race brake master cylinder mounted on Battle Factory clip-ons. The CNC’d brake mounts and triples were all custom fabricated specifically for this bike.
The cockpit is dominated by an AiM Solo DL2 digital display, which also handles data logging via two GPS satellite constellations and a built-in database of 2,000 racetracks. On a more analog note, Yoshimura supplied the oil pressure gauge, control switches and buttons. And there’s a modern-day carbon lever guard, and an ACTIVE quick throttle.
Going to the clutch side we have an adjustable Brembo RCS19 to actuate the slave cylinder from K-Factory (who also furnished a custom sprocket guard). Jason’s also upgraded the clutch with a heavy-duty race-specific clutch and basket from F.C.C.
Oil cooling duties are handled by a 13-row set up from PLOT, and under the gas tank cover is a SuperBike83 inner race tank that feeds high-octane juice into the Mikuni flatslide TMR40 carbs. The ignition and spark are controlled by a trick AS UOTANI SPii Advanced kit, but the charging system has been removed.
The internals of the 16-valve, 1,156 cc inline four engine are currently unmolested, and perfectly fine. But in the future, Jason will add Yoshimura cams and valves for a little extra fillip.
Breathing is via handmade headers and a mid pipe from NOJIMA, with gases exiting through the beefy 60mm outlet of an SC-Project GP-M2 can. Power hits the back wheel via DID ERV racing chains “and a good selection of sprockets, both front and rear, depending on my mood and how I’m performing!”
The ultimate trick part, though, is a one-off custom swingarm from Mr. Numari at Super Build Maximum. “His fabrication talents have been used at the highest levels of motorcycling,” Jason enthuses. “It’s an honor to have his craftsmanship (and artwork, if you will) on my machine.”
Just above the swingarm are fully adjustable Babyface rearsets—better known as Sato Racing outside Japan. “We had to custom-make the base block because there’s no specific kit for the GS. We modeled it on a set intended for a Ducati Monster M1100.”
The Suzuki is now finished and ready to roll, but it’s a waiting game. “I’m patiently awaiting the reopening of the track to test her out, and prepare myself for the battles in November,” says Jason. “Podium or not, just to race in this prestigious event is an honor for this ole boy from North Carolina!”
Given Jason’s racing pedigree and the specs of this incredible machine, we’re banking on a podium finish.
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