Is the 550 Four the best all round Honda of the 70’s? It just might be. Owner Kevin wanted a Honda CB cafe racer and after owning the smaller CB350 twin he knew something a little larger from the same family tree was going to be right in the sweet spot for this project.

History

In the mid 70’s many manufacturers were still experimenting with their public offerings, including Honda who already had the smaller CB’s (350, 400’s etc) and their big CB750. But it was the battle for the mid market that produced a number of new bikes including the Yamaha TX500 and Suzuki GT550.

Honda evolved the CB450 ‘black bomber’ twin into a CB500 twin to compete, but soon replaced it with a 4 cylinder 500 version. It wasn't long before the 500cc mill was taken out to 544cc to create the CB550 Four, but it took until 75/76 that Honda had ironed out most of the early issues with this model. This left only few years where the CB550 Four really was the ‘best of both worlds’ in terms of size, weight and performance before the model was finished in 1978.

Reviews lauded the 550 Four for it’s better performance than the smaller CB’s and better handling than the flagship 750’s. It wasn't as fast in a straight line as the bigger CB, but a stiffer frame and lower centre of gravity when compared to the 750 meant that it was well regarded as being easier to ride, especially for those under 6’ft tall.

As with any bike of this era, we discussed with Kevin the importance of doing the ‘whole job’ on an old bike like this to ensure trouble free riding once the build was complete. It can be daunting at the start, but Kevin agreed that going through every component on the bike was essential. In reality, it does save time and money ‘doing it once and doing it right’ so away we went.

Getting started

First port of call was the motor, which was pulled out for full inspection. The top end needed work and 1mm oversize pistons found their way into fresh bores. The head was completely torn down and leak tested before being completely rebuilt with all new Honda genuine parts. While the top was off the bottom end was inspected and it was deemed within spec and screwed back together.

Keeping it in the family, a Honda CBR front end was sourced and dummied up for testing before being disassembled for rebuild and anodising. The front steering lock was modified to prevent the new forks from introducing themselves to the stock tank. Rear shocks were also spec’d at the same time to get the stance right from the get go. Old lower suspension bushes had to be cut out before new ones were pressed in at the bottom with new spacers at the top.

Getting the bike rolling in the right direction is a Cognito Moto front hub to suit the CBR front end. This took some of the pain out of changing front ends as it retained the ability to mount the CBR brake discs and lined up with the stock CBR Tokico calipers. 

The stock rear hub was retained and both wheels were laced up to new ‘Sun Rim’ outers from the USA using fresh nipples and spokes. Prior to reassembly both hubs, spokes and nipples were coated in satin black to match. Avon Roadriders in 100/90-18 and 130/80-18 wrap the wheels front and rear, new chain and sprockets getting them turning. A custom made chain guard made to be as ‘stealth’ as possible keeps things legal.

With the rear suspension and wheels specified the rear frame could be trimmed and adjusted to allow for adequate clearance. A custom hoop was welded on with a recession for an LED tail light to slot in. Once some major de-tabbing was completed a battery box and rear wheel splash panel were folded and welded up. 

Continuing the fabrication, the rear seam lip on the factory tank was removed and the back edge of the tank lowered to cover the hole exposed from using a lower seat. Two custom seat pans were then made to suit the new frame shape and rear tank profile, one for a full two person seat and the other as a single seater with a rear cafe style cowl. The ‘cafe’ seat was an off the shelf unit that was modified to achieve a lower profile and to make it suit the shortened CB frame. It has a hinged seat pad (also required modification) that reveals a storage unit in the rear cowl.

A custom front guard was fabricated and mounted to the CBR upside-down front end. With the guard fitted a custom bracket for the bottom mount headlight could be made to position it as low as possible.

Continuing up the front end, Daytona speedo and tacho units were bolted to custom made mounts. The mini warning light panel sits on a custom shroud bracket nestled above the headlight between the gauges. CBR clip on bars, switch gear and ignition switch were sourced and fitted with a few light mods.

Once the fabrication was complete, all relevant parts were then sent off for powder coating in stain black.

Assembly

With all parts back from coating the assembly process began and soon started to resemble a bike again. The finished motor was lifted back into place. Rebuilt and freshly painted carburettors were refitted to the engine which was now finished in high temp satin black. Sanded cooling fins, laser etched and polished side covers provide some subtle detail on the new motor.

Exhaust gasses exit through modified stock header pipes which were cut and mated to new custom made 4-into-2 stainless pipes. Cone baffles and extra exhaust matting were fitted to the stainless mufflers before they were custom mounted ‘tight and low’ with a slight upsweep below the passenger foot pegs. The factory centre stand was modified to fit snugly around the new exhaust.

The ‘achilles heel’ for most old bikes is definitely the electrical system, especially where customs are concerned. To minimise future issues, all new electrical components were sourced and mounted. An Anti Gravity 8 cell battery now resides under the seat and all the components are mated via a custom aircraft-grade wiring loom. All wires were sheathed in braid and hidden where possible.

Motogadget indicators, Truflex LED tailight and a JW Speaker LED headlight all made their way on, accompanied by a trick little projector light which shines a Honda logo beneath the bike. At the back a modified Ellaspede Ninja Star licence plate mount extend the rego plate, rear reflector and plate light towards a more legal position.

A new custom clutch cable and braided brake lines fit to new brake and clutch levers up front. New grips and Motogadget mirrors slide on to bring the riders cockpit close to completion.

All other components were either painted, polished or powder coated across the whole bike. Fresh bolts, bearings and seals also replace almost all standard items with genuine Honda replacements used where possible.

Highlighting the important areas is a smooth ‘bone’ hue laid across the tank, headlight rim and cafe seat cowl. A classic double pin stripe shapes the tank and cafe cowl, with a pair of 3-D printed vintage Honda badges finished in satin black residing on the tank sides.

‘Mid tan’ leather wraps both seats in a horizontal stitch style. It also provides some detail and continues the theme across the custom wrapped fuel cap, grips, throttle pull elbow, kickstarter and passenger foot pegs. Always wanting to be part of the build process, Kevin was responsible for the patterned leather on the grips, kick starter and pillion foot pegs. 

Finishing thoughts

With the ‘whole job’ now complete Kevin can enjoy some classic Honda cafe racer riding without the worry of leaving a stone left unturned. It’s a credit to him that he was willing to ‘do it once and do it right’ on this build and riding the bike certainly reflects that.

As the original reviews suggest, the CB550 Four really does have the right mix of power and agility. 40 years later and now with some custom, aesthetic and mechanical improvements Kevin can continue to enjoy Honda’s middle market machine for years to come.

Albums we listened to during the build of this bike:

Photos and Features: