Suzuka Style: Suzuki GSX-R1216 “Yoshimura”

Slabside Spendor: 1987 Suzuki GSX-R1100 from KOS’THOR… 

Hideo “Pops” Yoshimura is one of the most revered names in motorcycle racing history. Born in 1922 in the Fukuoka prefecture of Kyushu Island, he developed an early passion for flight. In 1936, a French monoplane making a record-breaking flight from Paris to Tokyo crashed in the mountains near his home.

“Thrilled by the news, Hideo took a half-day hike to see the crash site and vowed to himself to become an aviator. ‘That’s what I really want to be. I’ll be a fly-boy!’ It was the golden age of aviation and much of the world, including Japan, was plunged into the aircraft development race.” –Yoshimura Japan

A year later, at just 14 years old, Hideo left home for the Imperial Navy Flight School, where he survived a near fatal accident when the engine of his Yokosuka trainer caught fire. 

“Hideo jumped out of the cockpit into the sky and desperately pulled the ripcord. Nothing happened. His parachute failed to open. As he falls helplessly through the air, he had a vision of his mother’s face. Just as he was making peace with his certain death he felt a sudden impact. The chute finally deployed at few hundred meters from the ground.”

It took Hideo two months to recover from the accident, and his dreams of flying were shattered. However, he went on to become the youngest flight engineer in Japanese history — an auspicious start for a young man who would become world-renowned in the world of superbike racing and tuning. 

In 1954, Hideo founded his shop, Yoshimura Motors, where he specializing in hopping up motorcycles for young American servicemen stationed in Japan. The soldiers began calling him “Pops” — a nickname that would stick for the rest of his life. In 1971, at the beginning of the four-cylinder superbike era, he moved his business to California, and the rest is history.

Working closely with Suzuki, Yoshimura and his team won the inaugural Daytona Superbike race, the Suzuki 8 Hours endurance race, the AMA Superbike championships in 1979 and 1980, and continued to be a dominant force in endurance racing, AMA Superbike, and Motoamerica in the 1980s and 90s.

For vintage superbike devotees, the Yoshimura Suzuki endurance racers of the 1990s remain some of the most iconic superbikes ever. One such enthusiast is our buddy Yohann “Yo” Kostrzewa of France’s KOS’THOR, who built his business importing performance vehicles from the USA to sell in his home country. 

“Today, KOS’THOR has a strong presence in France and internationally within the Kustom Kulture scene. From custom motorcycle builds, cafe racers, drag bikes, and track bikes (I ride a ZX10R on the track), to restoring VW Buses and Bugs, drifting, and gripping with the Legend Car, KOS’THOR is involved in all areas. I’m not a professional, just a passionate enthusiast who lives and breathes his passion.” -Yo

You’ll remember Yo from his “Pro Street 51” GSX-R1100 Turbo we featured last month — a nitrous-injected, forced-induction monster capable of well over 300 hp. Not surprisingly, Yo’s GSX-R has been one of the year’s most popular bikes on BikeBound so far. 

A Real Catapult: 1300cc Suzuki GSX-R Slingshot Turbo

You might recall that Yo actually bought two 1100 GSX-R’s from a friend who was selling his bikes. The turbo bike had been wrecked and Yo could only salvage the engine, and this earlier model — a ’87 GSX-R1100 “slabside” — wasn’t in much better shape. 

“The first one wasn’t in very good condition, so I completely rebuilt it in a ‘SUZUKA Yoshimura’ style, with a 1216 Wiseco engine, racing carburetors, and endurance camshafts.”

Legendary UK tuner Dave Dunlop of Fast By Me Turbo Systems had already done the engine work, installing a 1216cc Wiseco big-bore kit with forged pistons and a set of racing cams. Yo removed the engine for a refresh, repainting it a combination of gloss and wrinkle black, then reinstalled the motor with Nology plug wires, Yoshimura digital multi-temp meter, and a racing heat shield for the Mikuni RS40 flat-slide carbs. 

The bike is now running a YSS rear shock and R6 rearsets, and Yo fitted an iconic Yoshimura Tri-Oval silencer to a Devil 4-into-1 exhaust system. The fairing is a Ricambi unit, which Yo modified and reinforced during fitment. 

“A friend painted the base black and red, then I added racing decals, and we clear-coated over them. I applied a yellow clear coat to one of the headlights for a vintage touch.”

Yo estimates the bike makes some 160 horsepower, and the clicking of those Mikuni flat-slides at idle sounds downright wicked.

“It really feels like you’re on a racing machine from the 90s.”

What an awesome tribute to Pops himself and the Yoshimura heritage. Below is our full interview with Yo about the build, including many more photos and details.

Suzuki GSX-R1100: Builder Interview

• Please tell us a bit about yourself, your history with motorcycles, and your workshop

My name is Yohann KOSTRZEWA, aka Yo, I’m 48 years old and I live in Lorraine, France. I’ve been passionate about motorcycles since I was very young. I started modifying my first bikes at 18, after getting my license. My first custom build was an 1100 ZRX pumped with NOS — a real road wrecker.

Very quickly, I also developed a passion for American V8s, and I acquired a 1967 Camaro Prostreet, registered with the NSRA, which I imported from Florida. Since the French are very passionate about US vehicles, I decided to import vehicles from the USA and resell them in France. To establish my business, I created KOS’THOR in 2009. This project, along with the logo, had been in my mind since I was 18.

Today, KOS’THOR has a strong presence in France and internationally within the KUSTOM KULTURE scene. From custom motorcycle builds, cafe racers, drag bikes, and track bikes (I ride a ZX10R on the track), to restoring VW Buses and Bugs, drifting, and gripping with the Legend Car, KOS’THOR is involved in all areas. I’m not a professional, just a passionate enthusiast who lives and breathes his passion.

• What is the make, model, and year of the donor bike?

SUZUKI 1100 GSXR 1987.

• Why was this bike built? (Customer project, company promotion, personal, etc.)

 I bought two Suzuki 1100 GSXRs from a friend who was selling his bikes. The first one wasn’t in very good condition, so I completely rebuilt it in a “SUZUKA Yoshimura” style, with a 1216 Wiseco engine, racing carburetors, and endurance camshafts. You know the second one 😂

• What was the design concept and what influenced the build?

I wanted to build a racing motorcycle in Yoshimura colors — the kind of bike that could have raced at Suzuka in the 90s 😎

• What custom work was done to the bike?

As I mentioned above, the motorcycle wasn’t in great shape, so I completely disassembled it to recreate a factory-fresh machine. Just like the GSX-R Turbo, the engine was bored out by Dave Dunlop in England and converted to a 1216 WISECO.

I removed the engine from the frame to give it a refresh. I repainted the engine black and then painted the crankcases wrinkle black. I reassembled everything neatly in the frame using the original bolts, fitted Nology spark plug wires, and a racing heat shield to insulate the Mikuni RS 40 carburetors. 

The camshafts are also racing camshafts 😎. I installed a Yoshimura control unit to monitor engine temperatures.

The chassis is stock with a YSS shock absorber. I fitted a Yoshimura tri-oval exhaust to a complete Devil 4-into-1 exhaust system. I fitted rearsets from an R6. The brakes are stock with braided stainless steel lines.

I installed a Ricambi fairing that I modified and reinforced. A friend painted the base black and red, then I added racing decals, and we clear-coated over them. I applied a yellow clear coat to one of the headlights for a vintage touch. The bike runs great! 🏁🏁🏁

• Does the bike have a nickname?

 YOSHIMURA 😎

• Any idea of ​​horsepower, weight, and/or performance figures?

I haven’t put the motorcycle on a dyno, but it’s estimated to produce a good 160hp at the wheel.

• Can you tell us what it’s like to ride this bike?

The most impressive thing about this motorcycle is the clicking sound of the racing carburetors. You can even hear it in the video I sent you. It really feels like you’re on a racing machine from the 90s.

 

• Was there anything done during this build that you’re particularly proud of?

 I think the final result makes me very proud. Everything, actually 😎

• Is there anyone you’d like to thank?

• And also my friend Jean Damien from SPIRIT OF FIRST GSX-R.
• The Circuit of CHAMBLEY in Lorraine was used for testing.

Follow the Builder

Web: www.kosthor.com
Facebook: KOS’THOR Motors
Instagram: @kosthormotors
YouTube: @kosthor736

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