21st December 2021

Motorcycling Landmarks: The Honda CBX Six

In 1978, six cylinders with double overhead cams and 24 valves was a hot specification even for a sports car engine. BMW used exactly this spec in its M1 supercar. Imagine then, the impact of a motorcycle appearing with such an exotic power plant; inevitably the motorcycle press went into orbit.

When Honda launched the CBX1000 (actually 1047cc) it made much of the link to its earlier six cylinder Grand Prix bikes but this was largely just marketing. Though the same engineer led both design teams, the CBX was conceived from the outset as a ‘top dog’ road bike, not a racer. Honda’s competitors had been leaving it behind in the superbike stakes for several years and it was time to hit back.

To keep the width manageable, the alternator and starter drive were tucked away behind the cylinders, instead of adding to the span of the crankshaft. Even the carbs were angled inwards in two banks of three to liberate more space for the rider’s knees. With a claimed output of 105bhp and a hefty showroom price of £2200 in the UK (about 25% more than its rivals), the CBX was right at the top of the market.

Honda likened the CBX exhaust note to a Jumbo jet on take-off and cautioned riders not to tamper with the standard exhaust. That advice was never going to stick; soon a myriad of aftermarket six into one and six into two systems appeared. The resulting noise was an enthusiast’s dream; a high pitched wail, an octave higher than any four cylinder bike, rekindling the memories of the old Grand Prix Honda sixes.

Apart from the engine, the rest of the machine was largely unexceptional. The brakes and suspension in particular were barely up to the job of keeping control of the 550lb (250kg) monster. The thickly padded seat and upright riding position were very comfortable, except during high speed use, and the black instruments with red figures lit up at night like those of a jet aircraft, adding to the sense of occasion.

Of course the CBX was not the first six cylinder road bike, Benelli having claimed that prize with its 750cc Sei model in 1973, but the Benelli was of a much less ambitious specification with just a single overhead cam and three carbs. With higher manufacturing costs and a much smaller dealer network, the Benelli was always destined to be a small volume seller.

Owning a CBX today can be both challenging and rewarding. The six carbs with their minute fuel passages are prone to blockage if the bike is laid up for prolonged periods. Dismantling them for cleaning means synchronizing all six again afterwards. Likewise shimming the valve clearances becomes a labour of love when you have 24 to do!

If you can give a CBX the attention it deserves, it will reward you with a supreme riding experience. Despite the intimidating appearance the steering is light and positive, the controls smooth and convenient and the sound utterly addictive. The CBX should be on every classic bike enthusiast’s ‘bucket’ list.

What's your opinion on the Honda CBX Six? Let us know in the comments!