Motorcycle History: 1965 Honda CB450 – The Black Bomber Or The Prophet

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– Posted on March 8, 2015

(first posted 7/1/2012)   You might look at the bike above and think that this is yet another story about an old motorcycle long forgotten by those who aren’t old-bike “junkies.”  And you’d be wrong.  This bike not only was a paradigm shift for a major manufacturer, but it literally made an impact around the globe. Although it did get one or two things wrong, the Honda CB450 showed the way forward: It was the first of a long line of bigger bikes from Japan, and the first Honda powered by a DOHC engine.

Widely recognized as one of the most important Honda motorcycles ever launched, the CB450 Black Bomber is celebrated as both the company’s first “big twin” and the world’s first volume-produced DOHC bike.  Despite the flood of Japanese 500-to-650cc twins and triples into the U.S. during the 60s and 70s, it was this bike that finally opened the flood gates – but the CB450’s importance doesn’t end there.

Why did Honda build it?  When Honda started exporting motorcycles to the United States in 1959, it was the world’s largest  motorcycle manufacturer, selling some one-half million small bikes worldwide (the group pictured above was typical of their lineup at the time.)  It didn’t take them long to notice the much greater potential of the U.S. market, and so came the Hondas.

Instead of gearing an advertising campaign toward, well, gearheads, Honda went with the theme, “You meet the nicest people on a Honda.”  It targeted and very successfully tapped into the leisure-rider market, sending annual sales from 65,000 in 1962 to 150,000 the following year.  And if that’s not impressive enough, scroll down. When you hit the Top 40, you know you’ve really arrived.

Honda had been exporting a full mix of bikes at the time, from the 50 cc Cub to their biggest bikes, the 250cc Dream and 305cc Hawk.  Trouble was, most North American bikers had been raised on Triumphs and Harley Davidsons and thus didn’t consider Hondas real motorcycles.  Honda realized that without a product overhaul, no amount of success would change that perception.

 Initially, the British and American motorcycle companies didn’t consider the little Hondas much of a threat.  Had they looked closer, they might have realized that the influence of the new kid on the block had actually helped to boost the sales of all motorcycle makes.  At the time, the British manufacturers that lived on the sales of their 650 twins  believed Honda to be incapable of producing anything comparable…that is, until 1964, when someone spied Honda personnel testing a 450cc twin at the factory track in Suzuka, Japan.

The CB450–available only in black, hence its nickname–served notice on the world’s motorcycle industry that  Honda certainly could build larger capacity machines.  What’s more, it featured superior performance and greater technical innovation versus its European competition.  In short, this machine blew open the door through which Japanese manufacturers entered the big-bike market.

 In addition to being the first DOHC production bike, the CB450 pioneered the use of torsion bars instead of valve coil springs to shut the engine valves.  Owners were well advised to heed two major caveats: Warm up the engine before revving it, and change the oil frequently; the factory-recommended interval between changes was 1500 miles.

Honda designed the CB450 to put them on the big-bike map alongside the British manufacturers, and it did, although its sales fell a bit short of expectations. In the big picture, however, the CB450’s sales numbers are of secondary importance.  Its truly important achievements took place in what it didn’t do: it didn’t leak oil, and it didn’t fail.  Owners were relieved to find that the “Prince of Darkness” was English, not Japanese.  Still, the bike needed to diet:  At 444cc, it weighed 412 pounds dry–almost 50 pounds more than a 650 Triumph.


At the time the CB450 came out, only purpose-built motorcycles had dual overhead cams. As a result, it was disqualified from some English races for being too similar to a factory racer, despite the fact that Honda didn’t build it with racing in mind.

Honda aspired to be known as a builder of high performance consumer machines, and the CB450 was their first attempt at that goal.  It fell short of being competitive with larger bikes built for performance.


It did have a sister bike, the CL450 Dual Sport, or Scrambler.  Although most of the differences between them were cosmetic, the CL450’s higher pipes, braced handlebars, and aggressive styling were better suited (but not by much) for off-road riding.

Initially available only in kit form for the 1967 CB model.  It was officially released in 1968 as the CL450K1 “Scrambler.”  That year also saw the introduction of a five-speed gearbox.

In 1971 I rode one of these kitted bikes that belonged to a friend.  At the time I owned a Honda SL175, which was a small four-stroke, dual purpose bike.  My friend’s bike was impressive, but several of its traits I found somewhat less than stellar.  Compared with my bike, I found his CB450 to have excessive weight and vibration, not to mention several gaps in its four-speed transmission.  It was way too heavy to do well off-road.  Yes, I know that the 650 Yamaha I had later also was too heavy, but it shared none of the Honda’s other undesirable traits.  It would have made a much better desert sled.  I was happy to get off that CB450 and back on my bike.


The CL450 received changes much more slowly than did the CB model.  Although the CB450 got a front disc brake in 1970, Honda decided to continue with drums on the CL450.

Despite its Grand Prix-developed technology, the 450 simply wasn’t enough engine for such a heavy bike.  American Honda wanted more.

At the time, the biggest engine being made in Japan displaced 650cc and represented just a few percentage points of total sales, largely due to mandated (and repressive) insurance and tax rates.  American Honda was asking for bigger and more powerful bikes, but Honda of Japan didn’t quite know what that meant.  Later, Honda learned from a reliable source that the British were developing a three-cylinder 750, and instantly the target became clear.  The result, of course, was the CB750 – and motorcycling hasn’t been quite the same since.


The picture above is reported to be a spy photo of the prototype CB750.  But what’s really interesting thing about the CB 750 is its SOHC engine; in fact, and with the exception of the CB450, a SOHC engine would power practically every other contemporary Honda bike.  Why the step backward?  Did the 450’s minor problems made Honda DOHC-shy? Or just maybe it was this:

After the DOHC Kawasaki Z1 900 four arrived in 1972, the Honda fours suddenly looked old-fashioned.  Starting with its next generation of fours, Honda made a permanent switch to DOHC engines. Does that Kawasaki engine look like two 450 engines side-by-side?  Even the displacement is right.

By 1975 the CB450 was very long in the tooth.  The bigger CB750 had been out for five years, but Honda felt they still needed a middleweight twin.  In truth, the 450’s biggest drawback was the two-stroke technology of some of its competitors.  A Yamaha 350 or Suzuki T500 would absolutely eat it up.


Honda’s easy solution was to bump up their 450 to a 500 by doing little more than lengthening the stroke.  This Honda CB500T was the result.  If the 450 vibrated, the 500 registered on the Richter Scale.   In magazine road tests, more than one rider said Honda had committed the mistake of making an aging bike that much worse.  Honda restyled the 500 to make it look more the new style that the 750 four introduced.

According to Wikipedia, the CB450 engine was modified and used in their Japan-only N360 and U.S.-bound N600 passenger cars, but that may be less than actually true (as so many things in wiki).  The Honda N360 and N600 had a SOHC head, and don’t really look like the CB 450 engine at all.  Maybe some aspect of it did contribute or influence the mini-car engine, but it’s not exactly apparent from looking at it or its specs.

 I traveled all over Hawaii in one of these in 1971, when I visited my cousin there.  The car struck me as being considerably more spry than any of my 40-horse Volkswagens, perhaps because it was so light.  It seemed to have no torque and endless revs.  I wonder what the VW mill would have felt like in something like this. (Honda N600 CC here)

The Honda CB 450was far from perfect, and was not a sales success.  Perhaps it came out too soon, before it was fully fleshed out.  But even if it wasn’t as much of a game changer as the 750 Four, or the earlier Honda twins, it did foreshadow the modern motorcycle engine.  Almost every production bike engine within a few short years would pay homage to the 450’s classic DOHC design and construction.  Just looking at one was like peering into a crystal ball, even if riding it still had one in 1965.  Honda hadn’t yet perfected time travel.