Oldies: A short history of the famous RC 174 also called "Honda 6"... (7)

To fully understand the importance of what is called "the Honda 6" in the history of motorcycling, leading to the RC 174, we can obviously place it on a technological level, but also insert it into the saga of the duel between the International Motorcycling Federation and the builders, a worthy parallel to that of the police and the robbers!

Find here the introduction to this short story of the very famous RC 174 also called Honda 6.

This series of articles is inspired by the announced presence of the most authentic replica of la HondaRC174 during the Sunday Ride Classic on the Paul Ricard circuit, May 17 & 18, 2025...

1 / Presentation

2 / The context

3/ The first Honda 6

4/ The RC174

5/ “6 and” end… or almost!

6/ Beale's lines

7 / History repeats itself

But Beale's bike isn't perfect in some people's eyes; there are some inconsistencies and technical "shortcuts" due to not having all the elements. The replica is not exact.

It was at the very end of the 2000s that two friends: Guy Coulon et Julien Charnolé choose to embark on a replica project in turn with an absolute level of requirement: the motorcycle is legendary, it deserves total respect for the smallest detail. The duo is perfect with a wide addition of skills: Engineering and subcontracting for one, Japanese networks and perfect mastery of manufacturing for the other.

After the Beale adventure, the duo realized that gathering all the information was essential to successfully complete the project and avoid mixing elements from different generations, which could lead to errors. It was important to fully understand all the versions, the chronology, and the differences between them. Because the Honda 6 is far from being a single version!

The treasure hunt is intense, you have to gather information, some parts are possible to remanufacture, but not all. You need plans for what's missing... It's long. The trigger for the start of the construction will be... the sale of an original carburetor bank... on eBay! Incredible but true.

Thanks to Covid-19, so to speak, the project is accelerating. Guy locks himself in the workshop in Bormes les Mimosas, Julien will be able to decipher the period "blue prints" (the 1:XNUMX scale plans shown by the Japanese knowledge network) and provide a lot of information for the construction.

After several years of investigation and information gathering, Guy and Julien are able to differentiate all the versions, both in chassis and engines.

For example, it was when they started manufacturing the chassis that Guy and Julien understood that the first replicas were based on the RC166 (250cc) despite the misleading presence of the blue 350cc plates. The frames on the original plans have nothing to do with the RC166 and RC174. Nothing at all! The diameters of the tubes, their positions, the footrest supports, even the mountings of the exhaust clips or the shape of the rear mudguards change. Everything looks the same but nothing is interchangeable!

And on the engine side, they will understand that the 166 RC250B (1967 cc) used RC174 (297 cc) crankcases to benefit from the large bore but with a 6 mm stroke difference. No one knew this and no book talked about it. All this information will help them rebuild exactly without making mistakes.

For their project, they will choose the "350cc" version of the 1967 world championship. It is Mike Hailwood's favorite, you can also see 2 new ones for the first GP Western Germany with the number 60 in a photo.

The project is huge, especially with the requirement to redo everything identically. Each part is remanufactured EXACTLY as per the original plans, every engine part, every piece of chassis, the brake hubs, the frame tubes with designs and tapers that do not exist anywhere today, the thousands of engine parts, EVERYTHING is recreated with the utmost respect for the design and materials of the time. If the ignition was done with a magneto, they will remake a magneto. Crazy work!