When Shiro Nakajima isn’t tinkering away in his workshop or storming the B-roads across the foothills of the Yatsugatake Mountains, you’ll discover him on the observe. He’s a daily face on Japan’s traditional racing scene, and is simply as completely satisfied piloting race bikes as he’s constructing them. Even when he’s engaged on a traditional Café Racer or restomod for a shopper, the person behind 46Works can’t assist however imbue it with a way of track-ready efficiency.
Nakajima-san usually makes use of older donor bikes for his initiatives, however he’s not against spinning spanners on newer machines. So when the Japanese leather-based racing go well with producer Kushitani requested him to customise a 2023-model Aprilia RS 660, he jumped proper in.
Choosing an Aprilia for the challenge wasn’t random. Kushitani is a sponsor of the Japanese MotoGP racing star Ai Ogura, who competes aboard a Trackhouse Racing Aprilia RS-GP. The concept was for Ogura to journey the bike at a Kushitani-sponsored occasion on the iconic Motegi circuit.
Other than that stipulation, Kushitani had no notes for Shiro—leaving him free to do no matter he needed with the RS 660. “I not often customise supersport bikes,” he says. “I constructed a customized bike primarily based on a KTM RC8 earlier than, however that was a totally completely different strategy.”
With 100 hp and 67 Nm from its 659 cc parallel-twin motor, and weighing simply 183 kilos (403 kilos) moist, the Aprilia RS 660 is not any slouch. It additionally boasts an aluminum twin-spar body, alloy wheels, adjustable suspension, Brembo brakes, and a smorgasbord of digital rider aids.
Shiro usually upgrades the operating gear on his builds to eke fashionable ranges of efficiency from them, however that wasn’t essential right here. As a substitute, he targeted on the Aprilia’s aesthetics, with out shedding any of the traits that make it such sportbike.
“The design of a supersport bike fits race tracks and winding roads, however feels a little bit misplaced when driving to a café within the metropolis,” Shiro explains. “It’s like how ski attire appears to be like nice at a ski resort, however feels misplaced within the metropolis. The idea was to construct a supersport bike that will go well with the rider whether or not they journey on the circuit, on a winding highway, or to a café within the metropolis.”
Shiro’s first job was to check the RS 660 extensively on his native twisties. As soon as he had his head across the bike’s dealing with and ergonomics, a transparent path ahead started to kind. “The form of the tank is sweet for sporty driving, so I made a decision to make use of it as is—however the authentic fairing has a fancy form with sharp edges,” he says.
With every thing however the tank stripped off the Aprilia’s body, Shiro targeted on the fairing first. He sourced an aftermarket unit with smoother strains after which proceeded to therapeutic massage it even additional. The RS 660’s broad array of headlights was traded for a single spherical projector—no straightforward feat, because the bike’s lighting is managed by its CAN bus system.
One notable change is the absence of the RS 660’s fairing-mounted mirrors. “I don’t like how the mirrors stand proud of the fairing like an insect’s antennae,” Shiro quips. “I made mirror mounts to connect to the handlebars, and mounted a pair of Tanax 46Works mirrors on them.”
Transferring to the rear finish of the bike, Shiro fabricated a brand new tailpiece out of aluminum, whereas sustaining the unique ergonomics. “The design is my interpretation of a fusion between Nineteen Eighties sportbikes and fashionable MotoGP bikes,” he explains. “The end was left as naked aluminum, giving it a prototype look.”
The seat pan was made out of fiber-reinforced polymer, and the Alcantara upholstery was executed by Razzle Dazzle. The again pad might be eliminated to disclose a small storage compartment contained in the rear hump. Shiro echoed the entrance finish’s design by embedding a spherical taillight at the back of the tail cowl, and put in tiny LED flip indicators at each ends.
One other half value protecting was the RS 660’s carbon fiber SC-Challenge muffler, however the OEM mounting place was at odds with the redesign. Shiro repositioned the top can, fabricated a titanium part to attach it to the headers, and made an aluminum hanger to help it.
Drops Design Work dealt with the livery, which is so simple as it’s impactful. The blue sections mimic the colour of Ogura’s Aprilia RS-GP, complemented by blue pinstripes on the higher fairing and gasoline tank. Refined 46Works x Kushitani logos, achieved in silver leaf, add additional panache.
Shiro acquired the bike buttoned up in time for Kushitani’s occasion, with Ai Ogura tearing up Motegi with it as deliberate. Since then, it’s been relegated to show responsibility on the model’s numerous areas throughout Japan.
With a bit of luck, it’ll return to the observe quickly.
