
Every time that he builds a new motorcycle with his incredibly talented team, Hiroyuki Nakamura takes the opportunity to pass on a lesson to the world about what he has learned along the way. Between race bikes, one-off builds and his company AC Sanctuary’s signature RCM series of machines, he’s overseen the creation of more than a thousand incredible customs. But part of what makes him so good is that he’s always learning and always looking to push the quality envelope on each and every new bike. And when the client responsible for writing the cheques for this stunning resto-mod, RCM-619 Kawasaki Z1, went and ordered a second RCM bike halfway through this build, it gave Nakamura-san a chance to explain to us all his latest lesson.

As this Kawasaki Z1 progressed in the build phase, the client placed an order for another RCM creation, and for his second motorcycle he wanted a KZ1000 Mk-II. For the ever-cool Nakamura-san, this added a little extra pressure, two motorcycles for the same client, you really don’t want to let them down. Nor did he want to build two almost identical bikes, but as he explains today, there are certain parts of the build process that basically never change. “MotoGP World Championship, the World Superbike Championship, and the World Endurance Championship, the machines that run there are all machines that pursue only the ultimate in athletic performance. The parts are from world-renowned top manufacturers, such as Brembo brakes, OZ Racing wheels, and Ohlins suspension.”

And the same is true for almost every RCM build ever created, in these areas, Nakamura-san believes that it would be silly to try and reinvent the wheel, even if it was just to make a bike slightly different for a customer ordering two machines at once. These products are the best of the best and if Brembo, Ohlins and Oz are good enough for Marc Marquez, then as far as AC Sanctuary is concerned, they’re good enough for them too, and have stood the test of time. This is why Nakamura-san has focussed his business on three main areas, chassis development, engine building and creating a line of parts and pieces that bring classic bikes into the 21st century, while still retaining those looks of old that we all know and love.

And it is in the chassis and engine that he can offer his customers a great deal of variety, it’s just that when you look at each bike, it’s not easy to see those changes, and you can’t exactly see inside the engine either. So, while this might look to the average punter like a stock-ish Z1, starting with the frame, it is anything but. The original tubular steel item goes into the company jig, designed just for Z’s of this era, and then using lasers, is neatly straightened out to stock spec. Then it’s blasted with a media course enough just to take off the paint, revealing any imperfections, rust or cracks in the metal. Now one of the technicians can go to work, replacing any bad metal, adding gussets around the neck and swingarm pivot, and laying down extra welds in key areas.

On this bike, things are then taken to the next step, with new seat rails added, and some very large gussets around the centre posts. New mounts and alignment are added for the 17in wide wheel conversion, and by the time the whole thing is hit with a slick coat of black powder, most are none the wiser that this chassis is now a serious piece of kit. The next step is where Nakamura-san has spent years developing his own line of products, and that’s in the parts that are used to bolt those big brands onto his frames. The traditional way up Ohlins E×M package forks, meet the Kawasaki frame by way of an in-house designed and built Sculpture SP Type 1 steering stem kit.

At the back of the bike, the Ohlins Blackline twin shocks bolt to carefully laid out upper mounts for the perfect geometry, and at the bottom end of the shocks, meet the Sculpture RCM wide-style swingarm. The lightweight Oz Racing wheels are next to join the party, and it’s all hand-machined axles and nuts that attach them, and for the Brembo calipers it’s a set of ACs mounts, which allow the traditional forks to run a radial caliper. Nakamura-san’s brilliant approach is not to try and compete with these big companies, but instead build the parts that make their products work to their full effect on his machines. And from the clip-on bars to the rear sets, the sprocket cover and a whole lot more, it’s all made under his roof.

This is exactly how every engine is dealt with at the company too, simply by walking across the hall to the building that houses Nakamura-san’s DiNx engine building facility. Not even Kawasaki could build a Z motor like the lads at Sanctuary, and from all of the machining, the head work, valve train and precision assembly, it’s all made and pieced together under the watchful eye of the master. Mikuni supply the carbs because like the other big brands, they’ve nailed the process.

But the rest of the externals come from Nakamura’s Nitro Racing parts catalogue, from the thermal management and that trick oil cooling system, to the full titanium exhaust system, muffler and all. The final displacement for this bike was set at 970cc, and all are confident it will handle years of abuse.

So, finally, you arrive at the classic and still stunningly beautiful looks of RCM-619, and having dedicated his life to the Z bike, there was no way Nakamura-san was going to be panel-beating 50-year-old tanks and fenders for his stunning creations. As you can guess then, all of the body panels and replacement parts to get the look spot on, are recreated inside the AC-Sanctuary building from scratch. The seat too looks like it could be straight from the ’70s, but no, it’s a brand new AC part, with the latest in gel padding and waterproof materials.

The stock clocks are built the same way and the switchgear delivers the same result, and what you get is one resto-mod so incredible, the owner had to have a second before the first was even finished. The lesson; find the gaps in the industry, see what others aren’t doing, and then fill that need to the absolute highest of standards.


[ AC Sanctuary ]