Thundering Super-Sport: Honda CB900F Restomod

RCM-604 by AC Sanctuary… 

When the Honda CB900F first appeared in 1979, it wasn’t available in the States, as Honda was worried it might steal the thunder of the mighty CBX. American riders grew green with envy at images of European riders hustling the 901cc superbike through the winding roads of the Alps and Pyrenees.

The six-cylinder CBX might have boasted a higher top speed, but on a track or canyon road, the CB900F would be the clear winner.

“A thundering Super-Sports bike with devastating performance and an unwavering stamina.” -Honda

The CB900F was a direct descendant of the CB750F, featuring exotic technology for the era: four cylinders, dual overhead cams operating four valves per cylinder, and the cams linked to the crank by two silent-type cam chains. Max output was 95 horsepower at 9000 rpm — just 10 ponies down from the heavier CBX.

The CB900F would run the quarter-mile in the elevens, and by the time it reached US shores in 1981, top speed was clocked at 130+ mph. In 1982, Fast Freddie Spencer and team trounced the competition for a podium sweep in the Bell Superbike 100 at Dayona.

But the advent of liquid-cooled, aluminum-framed sport bikes was nigh, making the CB900F the height of a certain breed.

“The ultimate statement of the old air-cooled technology Honda had done so much to create.” -Kevin Cameron

Enter Hiroyuki Nakamura and his team from Japan’s AC Sanctuary, builders of the baddest Japanese restomods on the planet. While Nakamura-san is best known for his Kawasaki Zed and Ninja builds, he’s also brought his particular set of skills to the Suzuki Katana and Honda CB-F series, such as the CB1100F we featured a couple of years ago.

Resto-Monster: Honda CB1100F Restomod

With these RCM (Radical Custom Manufacture) builds, every facet of the original machine’s performance is upgraded: power, suspension, brakes, wheels, rubber, etc.

“As old bikes, customization and tuning can improve their dynamic performance, and the obvious difference in performance changes is a big attraction.” -Nakamura

For one of his latest and most time-consuming builds — RCM-604 — the owner chose the mid-displacement CB900F from the CB-F series. The chassis was stretched, straightened, reinforced, and repainted, while the wheels were switched to OZ Racing 17-inchers to accommodate modern rubber — Pirelli Diablo Rosso IV tires, to be exact.

The bike is now running 43mm Öhlins forks with Brembo dual-disc brakes and more Öhlins suspension in the rear. The rear swingarm is a billet Sculpture piece, an RCM exclusive produced in-house. While exotic, such trappings are to be expected for any RCM build.

But problems began to arise when it came time to overhaul the engine.

“The manufacturer’s stock is decreasing year by year, and the situation is getting tougher. Even though engine overhauls require internal combustion engine processing, it is difficult to replace consumable parts. In order to improve the completeness of the overhaul, it can be said that procuring new parts is the biggest challenge.” -Nakamura

In order to make the owner’s dream come true, Nakamura-san’s team spent hours “staring at auctions and overseas parts sites,” trying to find the consumable parts necessary to carry out the rebuild.

He says the issue is the same for any CB-F, CB1100R, or CBX1000, but ultimately it depends on the owner’s strong desire to make it happen.

“This is because without passion, it would not have been possible to make it, with a long production period of a year or with a sense of cost for parts that are difficult to obtain. The owner of this RCM-604 had exactly that kind of feeling, which is why he was able to make it happen. RCM for the CB900-F, which is obviously more difficult to obtain parts for than the air-cooled Z series or Ninja series. It has been reborn with modern specs and is still able to run well today.”

Full Gallery

Follow the Builder

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

More AC Sanctuary Restomods…

Radical Six: Honda CBX1000 Restomod - RCM-688: The First-Ever CBX Restomod from AC Sanctuary…   We’ve seen many masterful restomods from Hiroyuki Nakamura and the crew of AC Sanctuary — an assortment of Zeds, Ninjas, Katanas, CB1000R’s, and more. But we’ve never […]

860cc Kawasaki Z2 Restomod - RCM-617 from AC Sanctuary, inspired by Aitsu to Lullaby…   Most of us know the story of the Kawasaki Z1. Introduced in 1972, the 903cc UJM superbike was the fastest and most powerful Japanese four-cylinder ever […]

Straight Outta Sanctuary: Honda CB1100R Restomod - Possibly the Last: Honda CB1100R from AC Sanctuary…  In 1980, Honda unveiled their first-ever homologation special, the CB1100R. Based on the CB900, the single-seat sport bike boasted a 1062cc 16-valve DOHC inline-four producing 120 bhp […]

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 […]

Thundering Super-Sport: Honda CB900F Restomod - RCM-604 by AC Sanctuary…  When the Honda CB900F first appeared in 1979, it wasn’t available in the States, as Honda was worried it might steal the thunder of the mighty CBX. American riders grew green […]

King Zed: Kawasaki “KZ1135” MKII Restomod - Kawasaki KZ1000 MKII from AC Sanctuary…   The Kawasaki KZ1000 MKII was the 1979-80 version of the liter-sized Zed. It received some nice upgrades over the previous model, including fresh bodywork, larger carbs, electronic ignition, […]

RCM-632, Unveiled: Kawasaki Z900RS Restomod - Z900RS built to AC Sanctuary’s tastes…    In 2017, Kawasaki introduced the Z900RS, a 109-hp naked retro that recalls the storied air-cooled inline-four Zeds of the 1970s. “You remember the 1970s, when things were simple, […]

Air-Cooled King: Kawasaki “GPz1170” Restomod - A Warhorse Reborn: GPz1100F from AC Sanctuary…   In 1981, Kawasaki launched the GPz1100 to recapture the Superbike throne. It would be the most powerful Z1-based machine ever, offering 109 horsepower from the fuel-injected, air-cooled 1089cc […]

Radicalized: Suzuki Katana 1100 Restomod - Final Edition Katana, Radicalized by AC Sanctuary…   In 1980, the original Suzuki Katana 1100 rocked the motorcycling world with its angular, space-age design. It was the vision of legendary German designer Hans Muth, who’d been […]

Ninja Type-R: Kawasaki GPZ900R Restomod - 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 […]

Ice Cool R: Kawasaki Z1-R Restomod - Kawasaki Z1-R from AC Sanctuary…  As everyone knows, the arrival of the Honda CB750 in 1969 kicked off the superbike era. Over the next decade, a two-wheeled arms race between the big four Japanese manufacturers […]

Restomod Reborn: Kawasaki KZ1000MK-II - 1105cc Kawasaki KZ1000MK-II by AC Sanctuary…  The Kawasaki Z1000MK-II appeared in 1978, largely as a response to the Suzuki GS1000 and Honda CB900F. Known as the KZ1000MK-II in some markets, the machine had beautiful new […]

Mark II Missile: Kawasaki KZ1000 MKII Restomod - AC Sanctuary’s MKII Missile…  In 1979, Kawasaki introduced the KZ1000 MKII, which offered new angular styling and a slight power boost out of the 1015cc DOHC inline four engine, now making 93 bhp. The crank […]

Déjà Vroom: Kawasaki “KZ1165” Restomod - RCM-554: 1165cc Zed from AC Sanctuary… The Kawasaki KZ900 was the direct successor of the mighty Z1. At the time of its introduction in 1972, the original 903cc Zed was the largest, most powerful four-cylinder […]

Resto-Monster: Honda CB1100F Restomod - 1123cc Honda Restomod from AC Sanctuary…  In 1983, the Honda CB1100F arrived as the company’s king sport bike, designed to battle head-on with the 1100-class superbikes from Kawasaki, Suzuki, and Yamaha — bikes that were […]