CB750F Looks, RC42 Heart: HONDA CB750 Custom by STAGE ONE

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STAGE ONE's CB750

At first glance, anyone would think this is a beautifully finished CB750F in classic Spencer colors. But in fact, the base is an RC42, equipped with an engine derived from the CBX750F. Once you hear that, curiosity naturally follows about how this bike came together. "CB-Fs were getting expensive, and being older, I was worried about reliability. So I thought, since both are 750s, maybe the CB-F bodywork would fit," explains Kazama, the builder behind this bike. Kazama runs Stage One and also works on custom car builds. The project started from casual discussions among friends. The team gathered CB-F bodywork and began by mounting the fuel tank to establish the bike’s overall alignment.

"It’s difficult to modify the tank itself, so we adjusted the RC42 frame mounting points and bushings to fit the CB750F tank. After the tank, we moved on to the side covers and then the seat. We reused the original RC42 grommets—those rubber pieces that hold side covers in place—and modified the internal height so the stock CB-F seat would fit. Since the CB-F seat bolts in from both sides, we created corresponding mounting points on the RC42 frame. We carefully adjusted the overall balance, but the tail cowl was a bit tricky, so we referenced CB-F photos to align it properly, and the tail light and other parts fit naturally."

Mounting the straight, sleek CB-F bodywork onto the more rounded RC42 frame could have looked awkward. But here, everything aligns cleanly, while still using the original RC42 mounting components. "We didn’t cut away all the original brackets. We reused what we could, so the bodywork can be removed just like a stock CB-F, making it easy to handle any issues that arise on a tour. Anyone can perform repairs or maintenance, and if a panel cracks, it can be replaced without special modifications. I apply the same thinking when customizing cars." It’s a reassuring level of practicality. The bike itself belongs to a friend—also named Kazama—and everything besides the bodywork was customized by Stage One Kazama. Though he says it was made as a hobby, the results and concept are impressive and worth looking at for inspiration.

Bodywork

Fuel tank, side covers, seat, and seat cowl are all stock CB750F parts. No modifications to the parts themselves; the RC42 frame was adjusted so they can be removed and installed just like stock. The CB-F tank fits thanks to precise alignment with the RC42 frame mounts.

The seat is a stock CB750F, secured by bolts above the rear shocks, just like on a CB-F. On the CB-F, these bolts are located in front of the rear shocks, but on this bike the mounting brackets were reversed to fit the RC42 frame. The rear section of the seat was positioned to achieve proper visual balance.

The rear section of the seat was positioned to achieve proper visual balance.

Inside the seat, at the seat rail, the rectangular bridging piece at the rear supports the round rubber beneath the seat. Its height was adjusted so the CB-F seat fits cleanly. Side bolt mounts were welded to the RC42 frame, and the front mounting points were also modified.

Engine

The engine and chassis come from a CB750 (RC42), not the CB750F (RC04). Its air-cooled DOHC 4-valve inline-four engine is derived from the CBX750F successor, and since the RC42 carried forward the ’90–’00s air-cooled CB lineage, the CB750F bodywork fits naturally. Moriwaki engine sliders are installed for protection.

Chassis

The front forks use φ41mm RC42 stock forks, paired with Brembo axial 4-piston calipers and ACTIVE AC Performance line hoses. The front master cylinder will later be replaced with a new Nissin unit, chosen for easy maintenance anywhere.

The rear brake remains stock for the RC42, except for the brake line. The exhaust is a megaphone type that complements the Spencer-style color scheme.

The rectangular steel swingarm is paired with dual shocks, here replaced with Ohlins HO141, while the front and rear suspension remain stock-based. The wheels are RC42 stock 6-spoke, 3.50-17 front and 4.00-17 rear. The rearsets are from Moriwaki.

Gallery

Specifications

Part	Details
Frame	MORIWAKI Skid Pad Engine Slider
Brake	brembo Axial 4-Piston Caliper ACTIVE AC Performance Line
Suspension	OHLINS Rear Suspension
Steps	MORIWAKI Rearsets Kit
Drive System	RK 525XXW Drive Chain

Original Source of this Article

Heritage & Legends