In the past, we’ve labeled them the ‘Resto-Gods’ and it is hard to argue against the fact that when it comes to Resto-Mod motorcycles, AC Sanctuary is simply the best in the business. So, when they assign a special serial number for a bike before the build commences, you know the finished product is going to be something seriously special. Based on the bike that shocked the world when it was released forty years ago, this epic build has crossed the Pacific Ocean and taken three years to complete. Now we can present to you RCM-500, an absolute knockout Katana 1000 that is simply as good as it gets.

For the low down on how the build began, we spoke to boss Hiroyuki Nakamura, “The base model is a GSX1000S Katana that Mr. Diaz (the client) used to own when he was young. We went to the US, received the body at RCM USA Inc. in LA, disassembled it locally, and shipped only the necessary parts to Japan for production.” Unusually for AC Sanctuary, the client had considerable input on the build, with the Vegas-based owner communicating his wish list and design ideas back to the team in Japan.

With the US-spec parts in their hands it was time to get tinkering and the frame comes in for some extensive modifications. There is extra bracing at every key point to bring rigidity up to today’s standards and custom gussets were made to reinforce the areas that would see the increased load. The subframe was then modified to accept the planned new body parts, new shock mounts fabricated and the swingarm pivot point raised to increase the bike’s agility and speed at which it will change direction. Finally, the frame was smoothed out, painted in black, and fitted up with high-end bolts throughout.

The bodywork and style are still very much Katana, and yet none of the original parts remain, with AC crafting their own version on a modern retro retake. “The most distinctive feature is the change to the seat cowl of this super sports model,” which gives the bike a very new showroom superbike aesthetic from the rear. At the other end, however, it’s still very much the ’80s, with the unique Katana styling retained, and featuring carbon fibre winglets, LED square headlight and that unmistakable mini-screen.

Tying the two together is a new, hand fabricated fuel tank, which again is very much in keeping with the tradition of the donor. But slightly smaller and built from aluminium it provides a more slender look and considerable weight saving. The front fender and the rear hugger are both carbon pieces, that are attached with AC hardware. The side covers, radiator end caps,  and seat are painstakingly designed, fabricated, and finished in-house, with a Nitro belly pan to complete. “The hybrid paint job of carbon transfer and paint was done by YF Design, which is renowned for their work on RCM.”

And Nakamura is quick to give credit for the incredible look, “All the design and colour coordination was done by the owner, Mr. Diaz himself!” Of course, the look is only one part of the process in crafting a true RCM, so orders were placed for all of the best parts to get the braking and suspension up to speed. The ever present ‘SCULPTURE’ swingarm slots in and the rear is controlled by a set of remote reservoir Ohlins shocks. With the front end getting a setup to match, custom machined yokes are a work of art, and right way up Ohlins forks slide in.

Braking is handled by the incredible combination of Brembo’s latest calipers that clamp proudly Japanese Sunstar discs, front and rear. The unsprung mass is also considerably reduced with a set of Oz-Racing wheels that are shod in street spec Pirelli rubber and an Ohlins steering damper was added to keep Mr Diaz safe. To give the Katana a big kick up the backside, the stock engine was cracked open and completely rebuilt to RCM specs. With a new set of carbs gulping air via a set of picture-perfect machined velocity stacks. And the exhaust finishes out the major components, the bluing on the full Nitro titanium system showing that the bike has already been fired into life.

The cockpit is all business, with a custom dash utilising Stack instruments and that special RCM-500 plaque taking pride of place. Interestingly the one area the parties differed on was the mirrors of all things, the bike capable of wearing both traditional ears and bar end items that are to Mr Diaz’s liking. A patient man as it turns out, with the build slowed by Covid-19 and taking three years, and the bike is still in Japan.

With it not road legal in the land of the rising sun, it will be given a dyno tune and then track tested before this incredible machine is boxed up and sent to one very happy American.

[ AC Sanctuary ]