Source: Bike Bound
AC Sanctuary gives an original Ninja the Type-R treatment…
Introduced in late 1983, the Kawasaki GPZ900R — aka the Ninja ZX900 — was the earliest member of the Ninja series, and it changed sport biking forever. While a liquid-cooled 16-valve inline four making 115 hp might not sound that impressive today, the bike was a great leap forward for the industry.
“It was the first genuine 150mph superbike, dominated the 1984 Isle of Man TT races, and set the standard for full-bore sportsbikes for the next decade.” –Bemoto
Technical innovations included a new “diamond” frame that used the engine as a stressed member, a 16-inch front wheel derived from the company’s race bikes, an anti-dive fork with air-assisted springs, and that one-year-only red and charcoal paint scheme that still looks red-hot today.
Kawasaki had none other than Wayne Rainey on site at Laguna Seca for the press launch, and the president of Kawasaki Heavy Industries was present as well. Obviously, the company knew history was in the making.
Interestingly, the “Ninja” name came from Kawasaki USA’s marketing director, Mike Vaughn, who’d lived in Asia and named his 22-foot Colombia sailboat Ninja. It would be a branding coup and the perfect name for a bike that stole the thunder right out from under Suzuki’s Katana.
Of course, the US-spec version famously turned up as Maverick’s sports bike of choice in Top Gun, furthering the legend of the original Ninja.
Though the GPZ900R was a masterpiece of its day, sport biking technology has come a long way in the last 40 years since its inception. That’s where Japanese master Hiroyuki Nakamura of AC Sanctuary comes in. Nakamura-san is world renowned for his ability to preserve and sharpen the old-school character and style of vintage superbikes while bringing their performance straight into the 21st century.
Though he’s best known for his air-cooled builds, Nakamura does take on slightly more modern liquid-cooled projects like the one you see here.
“The owner, who’s been riding a GPZ900R for some time, has come to our shop many times for customization and repairs. We’ve had a desire to convert the bike to an RCM from the beginning, and now we’ve implemented the plan.”
RCM stands for “Radical Custom Manufacture” — the brand that houses AC Sanctuary’s highest-level restomod builds. When the crew dug into the donor bike’s engine, they realized the internals had some issues. On the plus side, that was the perfect excuse for a full, no-compromises “Type-R” Sports Package.
The motor was completely reconditioned inside and out with a rebalanced crank, honed and bored cylinders (972cc), and extensive head work. Internal parts like the piston pins and cams were given a DLC (Diamond Like Coating) treatment, while the rocker arms and piston rings received a WPC (micro ball-peening) treatment to reduce friction and wear.
The engine was outfitted with Wiseco pistons, Yoshimura cams, Nitro Racing oil-cooler kit, Mikuni TMR-MJN38 carbs, and a Nitro Racing hand-bent titanium exhaust with Grenade V-3 silencer — trick!
The bike is now rolling on 17-inch OZ Racing Wheels — a GASS 3.50-17 in front and PIEGA 5.50-17 in the rear, matched with a Sculpture swingarm, widened chainline (95mm → 103mm), and Pirelli Diablo rubber. Öhlins suspension and Brembo brakes round out the undercarriage.
Other highlights include Nitro Racing rearsets and fenders, Okushin paintwork, and a cockpit full of Defi gauges.
Nakamura says these early Ninjas used to be reasonably priced, but like most of the air-cooled superbikes before them, they’ve become more and more expensive over the years. For AC Sanctuary, the increasing rarity and expensive of donor machines is of utmost concern. In this case, it was nice to remake a bike the client already owned.
This has to be the hottest Ninja 900R we’ve seen — a bike that might actually outrun the F-14 Tomcat that Maverick races in the original Top Gun, hunched low on his own 900R!
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