On October 31, 2022, the CB400 SuperFour (SF), which has led Japanese naked sports for 30 years since 1992, will end its production. I would like to explore the origin of the CB400SF at the turning point of the end of an era. Of particular interest is the CR-1, which was even earlier than the CB-1, the predecessor of the CB400SF.
CR-1 adopted an aluminum twin-tube frame earlier than HRC
It is said that the Kawasaki Zephyr, released in 1989, created the naked boom, but did you know that there had been attempts to develop a naked model before that? One month before the Zephyr, Honda released the CB-1, which some say was the original naked model.
The CB-1 was a dud against the Zephyr, which had created such a boom that it became a social phenomenon, and it is needless to say that the Zephyr was the driving force behind the naked boom. The Zephyr was once a "No" to the Honda style naked, but the CB400 Super Four, launched in 1992, successfully turned the tables on the Zephyr.
Kawasaki and Honda had opposite approaches to naked, which, in the author's opinion, began with the 1984 CR-1.
This was a radical concept that could be called the NSR500 naked, incorporating an aluminum twin-tube frame and a 2-stroke 500 cc engine before HRC actually launched it in the market.
This trend is thought to have led to the introduction of the aluminum-framed Bros. in 1987 and the VT250 Spada in 1988. Although this is excessive equipment for a model that was called "naked" (as it was called before Naked)," it is typical of Honda's "technology-winning" approach.
HONDA CR-1 (1984). This design study model was exhibited at the 1989 MOVE exhibition at Welcome Plaza Aoyama and never actually went to market. The CR-1 was powered by the CR500R's 500cc two-stroke single-cylinder engine.
HONDA BROS Product 2 (1987). Cowl-less, quite similar to the image of the CR-1, was released with a narrow-angle 52-degree V-twin engine used in the Africa Twin and other models. The concept was similar to that of Yamaha's SRX.
HONDA VT250 Spada (1988). The 90-degree V-twin engine was mounted on the CASTEC frame, the world's first full-cast aluminum cast frame for motorcycles with hollow one-piece construction.
What they wanted from a naked was a commonplace motorcycle.
In contrast to the CR-1, which had an aluminum twin-tube frame that was ultra-modern, the CB-1 used a steel diamond frame. Based on the sales situation of Bross and Sparda, it is believed that the company decided that aluminum was too much. Nevertheless, the CB-1 retained the basics of a sports bike, such as the diamond frame, separate handlebars, and mono suspension.
The answer to why the CB-1, which was created as a cowl-less model of a sportbike, could not beat the Zephyr, the original naked bike, can all be explained by its difference from the CB400SF. The key point is that the CB400SF is a full-scale ancestor of the CB-1.
The CB-1's twin-tube frame-like structure of the diamond frame is replaced by a double cradle frame on the CB400SF, the Sepahan has pipe handlebars, and the mono suspension is replaced by twin shocks, recreating the style of a regular old-fashioned motorcycle. And this is precisely what made the Zephyr such a big hit.
However, the Zephyr had a miserable start, with the developer being asked by the sales side whether there were any selling points until the very end. It must have been a more difficult task than incorporating many new technologies to produce an ordinary motorcycle under the replica boom.
HONDA CB-1 (1989). The CB-1 was developed as an unprecedented cowl-less model equipped with a parallel four-cylinder engine similar to that of the CBR400RR. Perhaps with the Zephyr in mind, a semi-up-handle Type 2 was added in 1991.
HONDA CB400SF (1992). Developed based on the Project BIG-1 (later CB1000SF) concept exhibited at the 1991 Tokyo Motor Show. It was a 400cc version of the CB1000SF but was released before 1000.
KAWASAKI Zephyr (1989). Developed from a project to resell the Z2, the Zephyr was commercialized as an air-cooled 400cc price bike project. An easy-to-get price was also an important factor. ZEPHYR is an English word meaning "west wind".
KAWASAKI Z400FX (1979). The Zephyr is very similar to the Z400FX, and it could be said that the FX was re-released in place of the Z2. The developers described the Zephyr as just another run-of-the-mill motorcycle, but in those days when everything was new, it was conversely refreshing.
「30 years later」The last survivor was Honda's CB400SF
The 1989 Zephyr-induced naked boom was so hot that four Japanese manufacturers, including Suzuki's Bandit 400 and Yamaha's XJR400, released new models one after another, but later the bike market grew due to the aging of riders. They disappeared one after another due to changes in air quality and stricter exhaust gas regulations year by year.
The CB400 SuperFour, which was a top-selling machine even under such headwinds, evolved and was divided into three major generations: the first generation NC31, the NC39 with Hyper VTEC in 1999, and the NC42 with fuel supply changed to fuel injection. The NC39/NC42 was also available in Spec I-III and Revo versions, and there were three types of Revo models as well.
On the other hand, what plagued the pioneering Zephyr was the two words "air-cooled" in the air-cooled 400 cc price bike project. The maximum output of 46 PS was clearly inadequate for a young man like me at the time and was also a hindrance in complying with subsequent exhaust gas regulations.
And the CB400SF, which survived to the end, will end production at the end of October 2022.
HONDA CB400SF (1992). In late October, just before the end of production, the first generation CB400SF was displayed at Honda's headquarters to mark its end. Will there be a next model?
In the catalog for the first generation CB400SF, there is an interview with the developer, who simply states that it is not a pro-spec model when he says that the cam gear train is chain-operated. This is an answer that captures the essence of nakedness at its core.
