The Tiny Twin

Though somewhat overshadowed by their 400, 550 and 750cc brethren, Honda’s smaller CBs are just as much fun as their larger stablemates. Phil Turner leaps aboard a 175 K6 and is pleasantly surprised by the whole affair.

In the 60s Soichiro Honda proved without question, that the Japanese could build reliable, economical and cheap motorcycles, but winning over the hearts, minds and pounds of the fickle British buyers in the next decade demanded something more.
Although the superbike had well and truly arrived in the showrooms and the psyche of the British motorcycling public, parsimony was still the name of the game, and small capacity machines continued to be the mainstay of the market. Honda realised a straightforward revamp of the CB’s somewhat pedestrian predecessor; the CD, wouldn’t be exciting enough to tempt the superbike-hungry public, but those same buyers weren’t prepared to fork out superbike purchase prices or running costs. For this reason, Soichiro and his team decided a revamp was in order and set about taking the basic ingredients of the CD soup and spicing them up a bit. Out went the basic specification and bulbous looks, in came sporty chrome mudguards, exposed and adjustable rear shocks, uprated forks, twin leading-shoe front brake, 12v electrics and on the earlier models a friction steering damper. The new model also got a fully exposed chain and the combined clock/headlamp assembly was ditched in favour of a separate, more modern set-up.
Along with the new sporty image, came the engine credentials to back it up. Although the new model used the same air-cooled, four-stroke, twin-cylinder, sohc unit as the CD, the addition of a five-speed gearbox and twin 20mm carbs increased power output to a claimed 22bhp and top speed to 80mph – only five quicker than the CD on paper, but on the road it felt much livelier. This increase in performance didn’t come at the expense of reliability or economy either, 75mpg was more than achievable and the new, high-revving unit – redline was set at 10,500rpm – was as tough and durable as its older relative.
To make an engine so rev happy, yet reliable and durable at the same time, was testament to the ingenuity of Soichiro’s engineers. Similar in design and shape to the 250cc version of the CB, it uses roller bearings for the main, supporting a 360-degree crank, rollers are also used on the big ends and the cam is chain driven. Add to this a bore and stroke of 52mm and 41mm respectively and it’s easy to see why the motor spins so willingly and lasts so well.
This combination of style, performance, economy and reliability seemed to be just the ticket and the CB sold as well, if not better than the CD, so much so that if you cut your biking teeth in the 70s, chances are you owned one of these or knew someone who did.
As we all know, it’s for this reason that many classic Japs are now the subject of restoration, by those who can remember riding such machines in their heyday. Rather curiously, Eric Buckley, the owner of this particular bike, never owned a CB until later life, his reasons for reviving this tiny twin were a lot more down to earth; “I saw one advertised in one of the magazines, and they wanted a thousand pounds for it. I thought hang on a minute, I’ve got a bike that’s just as good as that, well not quite, but it certainly could be. So that’s what spurred me on.

Classic Motorcycle Mechanics July 2005 edition

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