HONDA CB450 K0
There are many theories about why the British motorcycle industry fell from grace faster than Icarus. The real reason, says Paul Miles, can be encapsulated in just three words: Honda Black Bomber
There are many theories about why the British motorcycle industry fell from grace faster than Icarus. The real reason, says Paul Miles, can be encapsulated in just three words: Honda Black Bomber
The Japanese firm had been extremely successful in the early 1960s with their complex racing machines, but the roadsters were limited to small capacity motorcycles, the 305cc sohc Super Hawk being the biggest. Tremendous though it was, its 90-plus mph top speed and pressed steel frame hardly threatened the impressive sporting twins from Triumph and Norton.
A factory visit in 1964 changed all that when a prototype was spotted being tested at the Suzuka track. Honda had to admit to developing a large capacity road bike. The subsequent 1965 release of the 444cc twin sent shock waves through the established bike industry, dealing the British manufacturers a body blow from which they never recovered. Their antiquated manufacturing equipment was wholly unable to respond to such a technological challenge from the Far East, and that’s very moment the pendulum swung away from the west.
Instead of yet another variation on the vibratory, leaky, kickstart-only pushrod twin theme, the prospective customer could now choose a completely oil-tight, electric start machine. The CB450 was also the first mass production motorcycle to feature double overhead cams, utilising torsion springs and a cheap to manufacture camchain, rather than expensive, exotic bevel towers. With a claimed 112mph top speed, the 43bhp CB450 looked, on paper at least, to be every bit a match for any production British motorcycle on sale, with easy starting and added reliability thrown in; not to mention the exotic specification guaranteeing bragging rights among your mates. And all this could be yours for £399 on easy terms.
Its release was immediately met with an FIM ban from production racing due to its twin camshaft racing connotations. The CB’s black and chrome finish soon earned it the nickname ‘Black Bomber’, actively encouraged by Honda UK in their marketing campaign. ‘Meet the big black Bomber, the biggest, beefiest touring twin from Japan!’
How could it possibly fail with a name like that and ‘too fast for racing’ catcalls? Well, as is so often the truth, the fears over a new era of racing dominance were unfounded. The Bomber wasn’t quite as fast as buyers had hoped, despite its 100bhp per litre output. Reports of somewhat suspect handling with under-damped suspension on original Japanese tyres raised a few chuckles from dyed-in-the-wool British bike enthusiasts, too. There’s even a hilarious period comparison test in Motorcycle Mechanics magazine between a stock Black Bomber, complete with twin mirrors, pitted against a ‘standard, but carefully assembled’ British
championship winning production racer Tiger 100. You couldn’t make it up. Despite the obvious disadvantage of not being carefully assembled in Triumph’s racing department with megaphone exhausts and clip-ons, the Honda was still only fractionally slower than the racing Triumph and managed to trounce it in the all-important braking tests.
Honda, although presenting the customer with a seemingly-familiar vertical twin design, differentiated the engine significantly from the British twins. Not only was it a dohc and not pushrod, but the crank was of 180 degree design with one piston rising as the other falls. This arrangement dramatically reduces primary vibration as compared to the traditional 360 degree cranks so beloved of Triumph et al. These changes result in a fundamentally different sound and feel from the motor when out riding.
A slightly uneven idle is typical, although the Keihin CV carburettors (a sort of Japanese SU), carry out fuel metering tasks admirably. Throttle response is immediate, but the Bomber does feel a little flat off the line when compared to the lusty immediacy of, say, a Triumph Bonneville. Further differences become apparent as the revs rise, however. Beyond 4500rpm the Triumph begins to feel very rough and at 6000 it’s pretty much all over. The Honda, like most modern engines and as we now all know, thrives on revs. As the Triumph’s pushrods begin to clatter with stress, the better-balanced Japanese twin simply carries on round the dial to a safe redline of 9500rpm. At an indicated 80mph
it’s as smooth as glass with perfectly clear reflections in the twin mirrors.
The example you see here is one of those original British market machines, restored to as close to original factory specifications as possible. The only upgrades are better rear shocks and tyres. It starts at the touch of a button, hot or cold, and is refreshingly quiet. Although considered a large capacity machine back in the day, by modern standards it’s tiny and feels more like a 250cc commuter to push around the garage.
The lack of urge at lower revs takes some getting used to and the Bomber demands to be ridden in a spirited fashion to get the most from the engine. Any question marks over the handling are quickly dispelled and it’s very easy to maintain a pace that would have a contemporary British bike owner fearing for their machine! Nothing goes wrong, falls off or breaks; it’s a Honda, after all and one built to a standard, not a price.
Honda had played a blinder. Doing nothing to suggest a power struggle with their competitors, they had quietly built up a network of dealers selling their small capacity machines to a new market; a sector for which the establishment had shown little more than contempt. When that new Honda-riding customer base were ready for a change to a
larger, sportier bike, so was the factory. Geoff Sullivan was a young engineering student and would-be racer in the late 60s, and he takes up the story.
‘I bought a Velocette Venom from Dodkins but could never start it in the morning, making me late for work all that first week. My dad threw it into the back of the van and we went to see him. We watched the Velo “expert” fail to start it for about half an hour. He eventually looked up and wondered if I fancied anything else from their stock.
‘I saw a two-year-old Bomber and asked if it was easier to start. He got the key and pressed the button. I thought “That’ll do for me” and rode it home. I used it every day for three years, riding to work Monday to Fridays and racing it at the weekend. It never let me down and I wish I still had it now.’
Despite this engineering brilliance the CB450 wasn’t as successful as the factory had hoped. At 400lb it was a little heavier than the competition (although it did enjoy an electric start), had perceived handling issues, and not everyone instantly trusted this brand new design of motor. Added to that was criticism of the four-speed gearbox – it was obvious that five speeds would be better – and a resistance to the styling, especially the humpbacked tank.
Honda quickly produced a dealer kit to transform any unsold Bombers. This kit, resulting in the so-called CB450D, comprised teardrop tank, sidepanels, upswept exhausts, saddle, rear light – and provided the inspiration for the next generation of 450s, the CL street-scramblers.
The CB450K0 represents a line in the sand for motorcycle manufacturing. Before the Bomber the Japanese were minor players, dabbling in small-capacity, low-profit motorcycles, similar to how Chinese manufacturers are perceived today. With the launch of the twin-cam 450, showcasing engineering talents and revealing their hand as potentially the greatest motorcycle manufacturer the world will ever see, the other factories were faced with a stark choice: match them, or go to the wall. The British industry did practically nothing, persevering with outdated pushrod twins until the bitter end. The legendary CB750/4 rolled into town a few years later, delivering the knockout blow, but by then the challengers had already been softened up and worked over – by the Black Bomber!