Zed’s Not Dead: Kawasaki KZ1000 “A16R” Restomod

KZ1000-Powered “A16R 005” from AC Sanctuary…  

Hiroyuki Nakamura and his team at AC Sanctuary are famous for developing some of the fastest, sexiest restomod motorcycles on the planet. Though they work with many different Japanese superbikes of the 1970s and 80s, their bread and butter is the air-cooled Kawasaki Z series: the Z1, Z1-R, KZ1000, and other variants of the Zed lineage.

AC Sanctuary’s restomod builds are branded as RCM (Radical Custom Manufacture), and one of the primary “menu” items on any RCM machine is a conversion to 17-inch wheels for the best modern tires available. However, the process requires much more than merely swapping in a different set of wheels. Nakamura-san explains:

“When the Z is converted to 17-inch wheels, the wheel diameter becomes quite small, so the vehicle height tends to drop significantly. For that reason, longer front forks and a steeper swingarm drop angle are used to keep the vehicle height the same as before… Moreover, 17-inch tires have overwhelmingly superior performance, including grip, so if you leave it as it is, the frame will lose. This is even more true if the engine power is increased, so reinforcement is applied to the frame to counter that…” -Nakamura

Sanctuary’s frame reinforcements come in Stages 1, 2, and 3, with Stage 3 being the best option for circuit racing and track time. These modifications are an outgrowth of the workshop’s racing experience, as AC Sanctuary doesn’t just build restomods that look the part, they race them. In fact, they’ve been actively racing Kawasaki Zeds on the track since the 1990s, and their RCM-240 Racer No. 1 has achieved a lap time of 59.913 seconds in the Super Monster Evo class at the Tsukuba TOT — an incredible time for an air-cooled superbike of the 1970s, no matter how heavily modified.

However, Nakamura saw the opportunity — and even the necessity — to take the Zed frame a stage farther. The two most important modifications he wanted to make were 1.) to enlarge the swingarm pivot from 16mm to 20mm while lowering it 10mm, and 2.) to enlarge the steering stem and bearings while moving the head 30mm lower and 25mm back. This would make the frame dimensions closer to modern sport bikes and compatible with the latest high-rigidity parts. However, the latter modification presented legal challenges, at least in his native Japan.

“If you try to achieve this with a standard frame, you have to cut the stem head pipe, but that would be completely against the law. And you can’t openly recommend a frame to a customer that has been secretly modified. For this reason, we thought that the only way to create a properly designed frame was to become a chassis manufacturer.” -Nakamura

So Nakamura-san followed the lead of such companies as Bimota, Egli, and Moriwaki to produce his own proprietary frame, and opened RCM USA here in the United States to manufacture it. In 2016, the RCM USA A16 debuted, offering an “original 17-inch wheel rolling chassis and air-cooled inline 4 engine.” The A16 chassis design evolved from the one-off frames that Nakamura and his team designed, built, and successfully campaigned in Japan’s Super Monster Evolution class.

“The A16 is an original frame motorcycle equipped with the engine of the famous KZ1000 produced in the 1970s.  Although it is a motorcycle equipped with an old-fashioned air-cooled engine, the chassis dimensions have been constructed to raise the performance to modern standards. It is a maniacal motorcycle that combines both elements of the good old days and the modern era, and produced in a completely limited run of just 30 units.” -Nakamura

The limited-edition A16 bikes are produced as a “Start Edition” in the USA and shipped to Japan with brakes, exhaust, engine, fuel injection system, and other main components already in place — these can’t be altered according to Japanese regulation. From there, the A16 machines are customized according to the needs and taste of each individual buyer.

Today we’re thrilled to feature “A16R 005” — the fifth in the series. While many of the A16 builds look little different from one of AC Sanctuary’s “regular” Kawasaki KZ1000 restomods, this owner pursued a slightly different vision.

“The  customization was not limited to preconceived notions, and he pursued a unique body line, creating a one-off aluminum tank with an original shape.  He created this one-of-a-kind machine, striving for ease of riding and a high level of perfection, and enjoyed it himself. It is a unique bike that gives off a different aura from other A16s.” -Nakamura

As Nakamura-san notes above, the one-off aluminum tank is a signature element of this A16R. Not only does it show off the underlying A16 frame, but it’s a dead ringer for the tank on the Z-Racer III, the company’s race bike that debuted in 2019 — their fastest air-cooled racer yet.

As for the tail, some of you might recognize it — it’s a Ducati Panigale 1299 unit modified to fit the seat rails of the A16 frame. We don’t always love recognizable tail units on motorcycles of a different make, but it fits well here.

Other highlights include a Z1000MKⅡ cylinder head, fully balanced pistons / conrods, rebuilt crank, billet throttle body, OZ Racing wheels, Öhlins Grand Twin shocks, YF Design custom paint, and much, much more.

This A16R almost looks like it comes from an alternate reality or parallel universe where Kawasaki and the other Japanese marques continued to develop and produce air-cooled, steel-framed, twin-shock sport motorcycles to the highest performance standards possible. Alas, it has been many decades since alloy-framed liquid-cooled sport bikes rose to supremacy in the sportbiking world and air/oil-cooled fours were relegated to “retro” status… Fortunately, there are maestros like Hiroyuki Nakamura and his team who carry on the torch.

A16R 005: Build Sheet

• Original aluminum tank production and in-tank fuel tank
• Original seat rail production and tail cowl conversion for Panigale 1299
• Original all-painted exterior
• Original carbon side cover production and quick fastener mount
• Original headlight mount stay production and LED headlight
• Original meter stay production and GSX-1000 meter conversion
• Rear fender and number stay production
• Round oil cooler upside-down processing and hose work change
• Swingarm black anodized
• OZ Racing wheels (Cattiva model)
• Ohlins rear suspension (Grand Twin)
• Seat base production and original seat production
• Plate type muffler stay production
• Variant silencer changed to matte black
• Battery case and electrical mounting bracket production
• Connecting rod full balance adjustment Special rebuilt crankshaft
• Piston full balance adjustment
• Clutch housing full balance adjustment and slipper clutch
• PAMS special billet throttle body
• Changed to Z1000MKⅡ cylinder head

Follow the Builder

Website: www.ac-sanctuary.co.jp
Facebook: www.facebook.com/ac.sanctuary

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