CB400F - The family's favourite son

Model History

In 1972 the biggest selling 350cc machine in America was the Honda CB350K4. So why did Honda produce the CB350F? The CB750 had captured the American market with 75,000 sold in the first year and 90,000 in the second. To capitalize on this Honda introduced the smaller CB500 which outclassed the CB750 in everything except pulling power and speed. The new ‘baby’ CB350F gave a four cylinder machine to riders who did not want the bigger fours, but in America the CB350F cost over $300 more than the CB350K4 twin which was lighter and quicker. The CB350F was introduced into the European market and sold very well in Holland, Belgium, Germany and France but in its two-year production life it did not sell well in America. So in 1974 Honda released the ‘café racer image CB400F Super Sport’ fitted with a sporty four-into-one exhaust system, very clean lines and a six-speed gearbox. The new CB400F soon earned the reputation of being the best in its field with its smooth all round ‘rideability’. The CB400F was aimed at the European market but also sold better in America. The CB350 Four was the ‘Prince’ of Honda four cylinder ‘Superbikes’ with the 347cc engine giving a turbine smooth 34bhp @ 9500rpm. This ‘baby four’ was one of the nicest machines that Honda have ever produced but it was never imported into the UK. We had to wait until 1974 for the introduction of the ‘Super Sport’ CB400/4 showing 37bhp @ 8500rpm with a sporty four-into-one exhaust system. The 400/4 could buzz through twisty country lanes and was guaranteed to put a smile on its rider’s face. The Honda CB400 Fours have always had a cult image simply because they are such fun to ride, giving motorcycling at its very best.

The baby of the 70s Honda brood is at first glance exactly that, a big bike in miniature. The seat, tank and general demeanour is low and the whole machine looks like it can be hoisted under one arm and carried off. Unfortunately the all up weight doesn’t match the lithe looks but the 400/4 is still a superb performer even when stacked against the accepted two-stroke lunatic machines of the period. The clue lies in accurate and determined riding, providing high corner speed and sharp lines are maintained then the under powered and slightly heavy Honda can be kept firmly on the tail of supposedly much more powerful and speedy machines. The 400F in motion
The move away from the design lead of the US market gave us low, almost flat handlebars making the bike appear even smaller that it actually is and with it a head-down stance from the moment one gets on the bike. The pillion seat doesn’t look big enough to seat an adult comfortably, because it isn’t, this bike was designed singularly to be a pure sports machine and such ‘extras’ are there almost for show.
Press the starter button once and nothing happens, hold it in and let the engine whirr over for a while and eventually things start to happen with the in-line four giving a passable impression of an electric Singer sewing machine, no mighty roar or such like howl just a smooth and pussy-cat like purr is all the 400/4 puts out, on tickover at least.
On the move the 400/4 is a delight to be sat on, well balanced, lightweight, mechanically silent and superbly smooth making the 37 horses on tap feel far less until the revs start to build and the engine becomes more vocal. The feel of the engine differs little from tick over to flat out, with only a minor rise in vibes around the five grand mark, corresponding with a slight dip in power.
Once above 6000 revs the acceleration starts to get exciting, hitting 8000rpm the exhaust note hardens to a more aggressive roar, pushing towards the 10,500rpm finale. The sound doesn’t seem to emanate from the end of the silencer, more from the down pipes, air box and the very metal work of the bike itself. The most riding fun is to be had well above the 8000-mark as here the peak power curve interjects neatly with maximum torque. Unlike the rest of the middleweight competition, hanging on well into the red-line reaps great rewards, the power dipping only slightly as the needle nudges the red wedge.
The bike is exceptionally agile and carries its extra weight well thanks to a great chassis design and layout. A 26-degree steering head angle coupled to a short and sharp 1344mm wheelbase, gives the machine great dexterity. With this sort of chassis set-up, changing line mid-corner doesn’t carry any of the wallowing found with Yamaha’s RD series, and there is simply no comparison with the Suzuki and Kawasaki middleweights in cornering.

Classic Motorcycle Mechanics December 2004 edition

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