There is an obvious curiosity about each and every custom motorcycle that is very rarely revealed. Just how much did the whole thing cost? Well, there is a bunch of reasons we don’t know the answer; protecting oneself from the wrath of a significant other, not wanting to reveal how much cash you have to splash around and workshops protecting themselves from unreasonable expectations. But today’s story allows us an insight from one of the world’s best builders as to where in a bike you should spend your money when budget restrictions come into play. Clearly, the end result need not suffer as Japan’s AC Sanctuary deliver another master class in resto-mod magnificence, with RCM-574 a beautifully blacked-out KZ1000.

The build number reveals just how much experience Hiroyuki Nakamura and his team have at turning out simply incredible customs. They’ve tackled many makes and models over the years, but the Kawasaki Z1 is the number one pick from their clients. But as prices only continue to rise on classic bikes, they’ve gotten simply out of hand with the ‘original superbike’, so the first suggestion for their customer from Tokyo was to start with the cheaper to acquire KZ1000, from later on in the ’70s.

Even so, they’re not cheap either, “The price of the KZ900 & 1000 has finally reached a certain price, but it is still a relatively reasonable price range compared to the Z1, and it is a good model as an air-cooled Z,” Nakamura-san explains. He also goes on to explain very wisely, that by starting with a later year model bike, you benefit from many of the factory improvements that came as each model evolved. In the case of the Z bikes, that includes a chassis that was considerably better than the original, although AC still added their own extra bracing and tricks.

With the frame readied, an enormous improvement added to all AC bikes is the fitment of the aluminium ‘Sculpture’ swingarm, which delivers 21st-century performance to a bike that’s more than forty years old. With a theme for the finished product very much in mind, the rear shocks are the same items used for other KZ builds, but this time fitted with black springs. To take that all to the next level, the machined billet triple clamps are finished in an anodised black and the Ohlins traditional forks are from the Blackline range.

Hanging from the bottom of the forks are Brembo calipers that are adapted to fit with machined mounts. The rear too uses a Brembo caliper on a custom lower mount, with all discs from AC’s own catalogue, with the front dinner plate sized items fully floating. Here is where you’d normally see a set of big dollar OZ Racing or Marchesini wheels. But with the budget in mind, Nakamura-san adapted a set of factory ZRX1200 wheels in a 17in diameter. As he explains, you don’t have to do everything at once, better wheels can come later, but the diameter change allows for quality Pirelli rubber.

When it comes to the looks, an AC resto-mod is always flawless, and to achieve this meant replacing the donor tank with a Z1 NOS piece. The tail lamp and rear cowl are factory KZ, “The tail lamps can be easily identified, but if you don’t look closely at the tail cowl, it’s hard to tell the difference.” Stock side covers and NOS emblems continue the theme and a custom front fender floats on a fork brace. The client was very specific when it came to the paint and colour scheme, it had to match the original black with gold graphics, “No twists!”

With a Z custom seat in stock by the guys at Daytona, it was decided this would be used rather than pay the extra cost to have a new one built, and the pan and latch were modified to make it fit. Shifting to the engine, the budget would allow for big power or a full blueprint rebuild, not both. “If you pursue more torque and power, it will be an interesting engine to ride, but first of all, it must be in perfect condition.” So, the engine was built to be 100% reliable with no corners cut, before a fully blacked out exhaust system and velocity stacks were added for an improved soundtrack.

With the client’s obvious love for the original machine, the factory instrument cluster has been restored to perfection and mounted on a custom bracket. The bars and the end weights are a collaboration between Daytona and AC to reduce vibration being transferred through to the rider’s hands. While the custom rearsets and adjustable levers ensure that the controls are of the highest standard. A traditionally styled headlight and indicators finish out the build and this KZ is simply another killer creation from AC Sanctuary! Knowing many more will desire such a bike, Nakamura-san has bought a bunch of donors, ensuring future clients are insulated from ever increasing prices.

AC Sanctuary ]