High-Level Craftsmanship Meets Custom Perfection: SUZUKI GSX1100S KATANA Custom by SANCTUARY

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SANCTUARY's GSX1100S KATANA

AC Sanctuary has been redefining the GSX1100S KATANA through modern upgrades and personal touches. Their work often features 17-inch front and rear wheels, inverted forks, and full custom paint—offering a blend of modernization and individuality. Notable examples include the RCM-500 (2022) and RCM-588 (2023).

“Most RCM build requests are still for air-cooled Z-series bikes, followed by the Ninja,” says Nakamura of AC Sanctuary. “KATANA orders come in only about once a year, even less than the Z900RS. That said, general maintenance like engine overhauls and carburetor tuning is still quite common.” In recent years, the availability of genuine KATANA engine parts has sharply declined, so the shop has begun keeping a full set of parts in stock for a single bike.

“KATANA orders were rare, but we had a good base bike, so we thought, ‘Why not build one ourselves?’ We had the stock parts, and our in-house DiNx division could handle precision engine machining. That gave us the freedom to go all out and make a bike that reflected our personal tastes,” Nakamura explains. The result is the RCM-644 KATANA, part of AC Sanctuary’s Craftsmanship series. Unlike typical made-to-order RCM builds, this bike was also intended as a demonstration model.

“This wasn’t just about building a bike—it’s our idea of how we would customize a KATANA today,” Nakamura adds. “Everything from the parts and colors to the 17-inch wheels and forged pistons reflects my personal preferences.”

The finished bike drew immediate attention. Even car enthusiasts from the same era as the KATANA took notice. It was displayed at the Tokyo Motorcycle Show in the Marunaka booth, which handles BS Battery products. At the same time, AC Sanctuary announced the bike for sale on their website, as Craftsmanship models are intended to be sold. The new owner was quickly decided—falling in love with the bike at first sight.

“Recently, KATANA customs have leaned toward a ‘stock-like’ style, preserving the original look,” Nakamura observes. “That’s fine, but some people want more. The RCM-644 might have tapped into that dormant demand.”

This is likely the last KATANA built under the Craftsmanship series, though made-to-order builds are still possible on low-mileage Final Edition GSX1100SY models. Regardless, the RCM-644 has set a benchmark for what a modern Katana custom can be.

Handlebar

The main instrument cluster is mounted on a one-off carbon-and-aluminum plate inspired by the original KATANA. It features a STACK ST700SR tachometer and speedometer at the center, with an ST3309 oil temperature gauge to the right and Motogadget Motosign Mini warning lights to the left. The handlebars use DAYTONA clamps and bars, with an Ohlins steering damper, part of the upcoming “Ohlins Steering Damper E x M Package,” scheduled for release in fall 2025. The front master cylinder is a Brembo Racing radial unit, and the clutch uses a KOHKEN wire-actuated mechanical holder. Both levers have been replaced with ZETA RCM Concept flight levers.

The photo shows what the cockpit looks like during nighttime riding. All vital information, including speed and distance, is displayed within the tachometer panel.

Unlike the stock KATANA, where the meters were mounted on the steering, this bike uses frame-mounted instruments for a lighter, more responsive feel. Front turn signals are small, one-off aluminum units mounted in the stock position. The windshield is an Ohno Speed “Takumi” model, and the mirrors are Magical Racing NK-1 Type 2 heads.

Bodywork

The exterior paint, handled by YF Design, is reminiscent of the classic KATANA red-and-silver color scheme but uses entirely new graphics and tones.

The seat maintains the original KATANA shape but has been modified for better footing and grip, with lightweight construction and new upholst

Under the seat, a custom oil catch tank and battery case house a BS lithium battery. The inner fender is also custom-made. Ignition is handled by AS Uotani SPⅡ, while the main wiring harness, regulator, and other electrical components come from Ohno Speed, a trusted supplier of KATANA-specific parts.

Engine

The engine has been precisely bored, honed, and decked at DiNx, increasing displacement from 1074cc to 1105cc with forged 74mm pistons. while the cylinder head received DiNx oversized valve guides for the KATANA, valve seat cutting, and lower surface machining, all handled by DiNx. The camshaft is a Yoshimura ST-1, and the engine is finished in GUN-KOTE. The frame was fitted with a dummy engine and then measured and corrected using laser alignment and stretch. After that, it received original frame reinforcement, a wide laydown modification, and inline processing to accommodate the drive-chain offset.

Intake & Exhaust

The intake uses 40mm TMR-MJN carburetors with Yoshimura dual-stack funnels. Gold accents are limited to the intake and front fork inner tubes.

The exhaust is a modern, high-spec system combining a NITRO RACING Weld Craft 3D titanium with a NITRO RACING Variant titanium silencer.

Chassis

The rearsets are NITRO RACING for the GSX1100S KATANA (’99 and earlier), paired with a NITRO RACING machined aluminum sprocket cover. The drive chain is an EK530RCM in black and gold.

The front uses Ohlins 2IFF5210 inverted forks, clamped with a Sculpture E x M Package stem kit. Braking is handled by Brembo GP4-RX calipers with Sunstar Works Expand 320mm rotors (red inner) and Allegri short-system brake lines.

At the rear, a Brembo CNC 2P caliper works with a Sunstar Works Expand 250mm rotor and Allegri lines. The rear suspension combines a Sculpture wide swingarm with Ohlins Black Line (SU143) shocks, including a block-piece stabilizer and an eccentric adjuster at the lower mounts for fine tuning. The wheels are OZ Racing aluminum forged GASSRS-A, sized 3.50-17 front and 5.50-17 rear.

Gallery

Specifications

Part	Details
Engine	YOSHIMURA Camshaft [ST-L1] Wossner High-performance Forged Piston Kit DINX Original Valve Guide for GSX1100S KATANA NITRO RACING GSX1100S KATANA Machined Aluminum Engine Hanger
Carb / Intake	YOSHIMURA Dual Stack Funnel System Basic Kit for TMR YOSHIMURA TMR-MJN34 Carburetor YOSHIMURA Original Aluminum Funnel for TMR/MJN
Exhaust	NITRO RACING 4in1 Weld Craft Titanium 3D Exhaust [Grenade TitaniumVersion 2] NITRO RACING Valiant Titanium Silencer
Frame	SCULPTURE Stem Kit for Öhlins Upside Down Fork GSX1100S KATANA [Type2] SCULPTURE 17 Inch Exclusive Wide Swingarm Silver
Brake	brembo Racing Radial 19 CNC Brake Master Cylinder (Front) brembo GP4-RX Radial CNC 4-Piston Caliper (Front) SUNSTAR Works Expanded Disc φ320 (Front) NISSIN Master Cylinder 1/2 (Rear) brembo GP2-SS CNC 2P Caliper (Rear) SUNSTAR Works Expanded Disc φ250 (Rear)
Wheels	OZ Racing MOTORBIKE GASS RS-A 3.50-17 (Front) OZ Racing MOTORBIKE GASS RS-A 5.50-17 (Rear)
Suspension	NITRO RACING Upsided Down Ohlins EX-Mode Package OHLINS Black Twin (SU143)
Steps	NITRO RACING Rearsets Kit for GSX1100S KATANA (’99 and Earlier)
Drive System	NITRO RACING Machined Aluminum Sprocket Cover EK CHAIN EK530RCM (Black and Gold) Drive Chain
Handlebar / Steering	DAYTONA Machined Clip-On Handlebar Clamp Set (Left & Right), Black Φ50 DAYTONA Machined Clip-On Handlebar Straight Bar 2-Piece Set, Black NOBLEST OHLINS Steering Damper “E x M” X-Mode Package KOHKEN Mechanical Clutch Holder ZETA RCM Concept Flight Levers Magical Racing NK1 Mirror TYPE-2 STACK ST700SR Stack Timer Dash System Base Kit STACK ST3000 Series Stepping Oil Temperature Gauge MOTOGADGET Motosign Mini
Oil Cooler	NITRO RACING Straight Oil Cooler Core 9-Inch / 13-Row
Bodywork	OHNO-SPEED Windshield Takumi NITRO RACING Universal Carbon Rear Fender NITRO RACING Carbon Front Fender (Included in E x M Mode Package)
Electrical	AS Uotani SPII Full Power Kit BS BATTERY BSLi-05 Lithium-Ion Battery OHNO-SPEED Hybrid Main Harness for GSX750S - GSX1100S OHNO-SPEED Regulator

About SANCTUARY

SANCTUARY is a custom builder that is good at Vintage motorcycles like Z1,Ninja and KATANA. They sell special parts which were born from trial and error that mechanics had repeated mounting and testing

SANCTUARY brand page

Original Source of this Article

Heritage & Legends