A High-Precision Build from On-Hand Parts: SUZUKI GSX750S KATANA Custom by MOTOTECH

• GSX750S
• Katana

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MOTOTECH's GSX750S KATANA

Fitting an oil-cooled engine into an air-cooled KATANA chassis has long been a standard method of boosting power, whether the base bike is an 1100 or a 750. But this particular machine, based on a GSX750S Gen 3, comes with a unique backstory.

“One of our customers used to ride a third-generation KATANA (GSX750S3),” says Mr. Sugiyama of Garage Mototech. “When he decided to stop riding, he passed the bike and its parts on to us. Later, in 2018, when Team KAGAYAMA entered the T.O.T in the Hercules class with their KAGAYAMA KATANA, we got involved in the project. One of the people who helped out said he wanted that exact KAGAYAMA KATANA. Of course, that wasn't possible—but it got us thinking. So we decided to build a machine with a similar feel, using the third-gen KATANA and parts we had on hand.”

The KAGAYAMA KATANA, also known as the KATANA1000R, is a race bike that combines a GSX-R1000 engine with a custom steel frame and KATANA-style bodywork. Among its variants, the first one built, dubbed “Type 1,” featured a CBR600RR swingarm and a Unit Pro-Link suspension system. This new build takes its inspiration from that design. While the KATANA1000R follows the traditional KATANA silhouette, this custom uses the third-generation model with its retractable headlight. Still, both bikes have a monoshock setup. On the race bike, the headlight was replaced with a number plate, and with this machine finished in blue and black, the resemblance is surprisingly close.

Although the third-gen KATANA has a monoshock suspension, the frame shape makes it difficult to install a shock mount. To work around that, the builder opted for the Unit Pro-Link system, where the suspension is self-contained within the swingarm. However, the swingarm's width posed a challenge—it was simply too broad for the KATANA’s stock frame, creating an imbalance. To address this, a spare third-gen KATANA frame was cleverly repurposed for both reinforcement and structural modification. The builder took this secondary frame and carefully welded it onto the outside of the main frame around the swingarm pivot area, effectively increasing the overall width.

Then, from the inside, they carved out just enough material to allow the wide swingarm to fit cleanly within. If you examine the bike closely, you'll notice the frame starts to flare outward from around the rear half of the crankcase, eventually matching the engine case width near the pivot—this is where the additional welding and fabrication work lies. It’s an inventive solution—not something most builders would readily think of.

The rest of the machine is also assembled from an impressive mix of repurposed parts: a Bandit 1200 engine, GS1200SS steering stem, front forks made from CB1300SF inner tubes and VFR800 lower cases, and RG51 wheels. Thanks to the Unit Pro-Link, the engine sits at a natural angle, and even with an FCR carburetor, it delivers smooth, year-round rideability. Though clearly inspired by the KAGAYAMA KATANA, this bike is the result of its own unique process, shaped by creativity and skill. The impressive presence it gives off is a testament to the ingenuity and careful parts selection that brought it to life.

Handle

The front master cylinder is a Brembo Racing unit, while the meter is an ACEWELL ACE-7652—designed with a one-body, one-panel setup. The clutch, originally a hydraulic type from the 3rd-gen KATANA/Bandit 1200, was deliberately converted to a cable type. The steering stem was replaced with one from a GS1200SS to accommodate larger φ43mm forks (up from the original φ37mm), and to switch from a 16/17-inch wheel setup to 17-inch front and rear.

Bodyworks

The seat was completely reworked—inner structure, cover, and pattern—into something more in line with modern custom styles, improving ride comfort, control feel, and footing.

The exterior parts, including the integrated tail light with turn signals on either side of the brake light, are stock 3rd-gen KATANA. On the tail section, you'll also find the signature of Yukio Kagayama.

Engine

The engine has been replaced with an 1156cc oil-cooled unit from a Bandit 1200, and the clutch has been converted to cable operation. Just below the front sprocket, you can see the frame tapering outward—this is because another GSX750S3 frame was added from the outside and welded on. At the swingarm pivot, a temporary double-frame structure was created, and the inner part of the original frame was cut out to make room for the swingarm and ensure proper chain alignment. The hollowed section was then closed off again to restore strength.

The FCR φ39mm carburetor is paired with a sponge filter setup, and the ignition system is upgraded to an Uotani SP2. The engine and carb layout offers good flexibility.

Chassis

The front forks consist of CB1300SF inner tubes paired with bottom cases from a 2002 VFR800, resulting in a φ43mm setup. The front brake uses Brembo M-4 calipers and Brembo Supersport discs.

At the rear, a CBR600RR caliper is paired with a SUNSTAR Works Expand disc. For the exhaust, a YOSHIMURA Duplex Titanium Cyclone exhaust system is combined with a YOSHIMURA Cyclone silencer originally designed for the Hayabusa.

The swingarm is a Unit Pro-Link type from a CBR600RR. Since only the swingarm and one side of the link need to be mounted to the frame, this design made it possible to build this bike. The rear shock is an Aragosta, supplied by Mototech. The wheels are 17-inch from a VTR1000SP-2 (RC51), sized 3.50 up front and 6.00 at the rear. The drive chain is an RK 520XXW.

Gallery

Specifications

Part	Details
Carb / Intake	KEIHIN FCRφ39mm JAM 3D Air Filter
Exhaust	YOSHIMURA Duplex Titanium Cyclone YOSHIMURA Slip-On Tri-Oval Cyclone 1 End
Brake	brembo Racing Brake Master Cylinder brembo M-4 Radial Monoblock Brake 4-Piston Cliper brembo Brake Disc Kit [Super Sport] SUNSTAR Works Expand Disc for Rear
Suspension	ARAGOSTA Mono Shock PHASE-1
Drive System	RK 520XXW Drive Chain
Handle / Steering	ACEWELL Multi Function Digital Meter
Electrical	AS Uotani SPII Full Power Kit (S.BANDIT1200-2)

Original Source of this Article

Heritage & Legends