Big-bore ’70s bikes get most of the attention. Then and now, the headlines slobbered all over the Kawasaki Z1 900, the Honda CB750, and the Suzuki GS1000. Now, the journos will often retrospectively admit the 550 and 650 fours were actually better all-rounders. But what if you wanted something even smaller? Kawasaki and Yamaha specialized in smelly two-stroke 350s, but Honda stuck with four-cylinder four-strokes—first, the CB350F in 1972 and then the CB400F in 1975.

Middleweight motor

By the mid-’70s, Honda had been building production inline fours for half a decade, and had the basics figured out. The 400F was air-cooled, with single overhead cam and two valves per head. Basically, it was a big-bored 408 cc version of the earlier CB350F engine. That motor had been a considerable disappointment, making under 30 horsepower. Even in the ’70s, that wouldn’t do in stoplight-to-stoplight action, or on the track. So, Honda reworked the CB400F with bigger valves, a slight bump in compression, and a tasty new 4-1 exhaust. Honda rated the bike for 37 crank horsepower at 8,500 rpm, and 24 pound-feet of torque at 7,500 rpm.

The 400 had a kickstarter as standard, as well as the electric boot. Photo: Bring a Trailer

The 400F had a six-speed gearbox, the first Honda with the added gear. This let the engineers compensate for the smaller engine, using a wider gear spread to provide more low-end grunt and also drop the revs at highway speed.

When the magazine test riders got their hands on the new bike, they seemed to think the new engine was a vast improvement over Honda’s previous four-cylinder 350. It still gave up some jam to the two-stroke competition (the Yamaha RD350 would make 39 horsepower if you had it on the boil; the Kawasaki S3 Mach II 400 was rated for 40 horsepower). The two-smokers might have accelerated faster, but the Honda was much more civilized for real-world use, with smooth, predictable power. It had better fuel economy, too.

The 400 engine had one other thing going for it: That chromed-out 4-1 exhaust was gorgeous. Even now, it’s considered one of the best-looking exhausts ever put on a factory Japanese bike. If you look at recent-production Honda 500s, many of them seem to have drawn inspiration from the gracefully swooping CB400F exhaust system.

Those drool-worthy 4-1 headers seem to be in excellent shape on this machine. Photo: Bring a Trailer

Sporting intentions

The engine was improved over the 350F, but Honda also spent some attention on the bike’s chassis and setup. At that time, most Japanese bikes had upright handlebars, an upright seating position, aimed at straight-up road use. Not the 400. This machine had slightly lower handlebars, and Honda moved the footpegs backwards a bit, so riders could tuck in for a racy stance. It had a more European stance, less like a practical UJM. It was still far from a factory cafe bike, though.

The frame itself was sensible steel tubing, nothing fancy, with dual rear shocks. On early-production models, Honda put the passenger pegs on the swingarm, so you could haul your sweetie on board if you really wanted … but it made more sense to chuck ’em, and ride the bike solo (on later models, the passenger pegs were on the frame). Honda put a single disc brake up front, and a drum on the rear.

Wait, are those passenger pegs mounted on the swingarm? Honda had a frame-mounted arrangement on some later-production 400s, and moved the rider’s footpegs further forward as well. Photo: Bring a Trailer

The 400F weighed 392 pounds with a gallon of fuel. By comparison, the first-gen CB750 weighed 513 pounds fuelled-up, and even the CB550 weighed 455 pounds when it was gassed up. The 400 was very svelte indeed, by those standards.

That helped win some fans in markets like the UK, where customers appreciated machines that blended sweet handling with enjoyable power. It was less of a hit in the American heartland, where headwinds can blow you across a highway lane, and the highways don’t have a lot of curves.

The magazines loved the CB400, but money talks. The Honda was priced higher than its own budget twins, as well as the two-stroke 350-400cc competition. Sales suffered as a result. Photo: Bring a Trailer

Sales disappointment

Although it was well-regarded by bike writers in its day, and still is, the 400F didn’t have the sales success Honda wanted. Ultimately, it just wasn’t as fast or cheap as the two-stroke 350 competition, and it was more expensive than practical twin-cylinder four-strokes in the 350-400 class, like Honda’s own CB360, or Kawasaki’s KZ400. Honda did sell more than 100,000 CB400F models, which sounds like a lot … but its CB350 twin sold 250,000 machines. The 400F and CB360 were both canceled in 1977, replaced by the CB400T, a four-stroke parallel twin. Honda didn’t sell another 400 inline four in western markets until the CB-1 came along in 1989. That was a far worse sales disaster in North America, and Honda hasn’t bothered bringing anything like this to our market since. On the sales floor, there’s no replacement for displacement.

A gorgeous example of a mid-70s middleweight. It’ll cost a pretty penny, though. Photo: Bring a Trailer

What about this machine?

This bike is for sale on Bring a Trailer, which means it’s going to look nice, and it’s going to be an expensive purchase. A New York dealer is selling it on consignment, with no reserve price, but that doesn’t seem to be suppressing the price. At time of writing, it’s sitting on a $5,000 bid, and in the comments, someone conjectures it might sell for as much as $15,000 US. Certainly, prices are going up for vintage Japanese bikes, and vintage bikes in general.

BAT sales are almost always higher than a local Craigslist/autoTRADER/Kijiji find; however, you’re often dealing with known sellers, and it’s not like there are many of these machines left abandoned in garages and carports anyway.

There’s some conjecture in the comments section about the originality of various parts. If that’s the sort of thing that concerns you, obviously you should do your due diligence before buying. Otherwise, if you’re like most of us … enjoy the photos, and save your $15,000 for something more practical.

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