CB400 FOUR Project

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The Honda CB400F was an inline-four engine, standard motorcycle made by Honda from 1975 through 1977. After introducing the four-cylinder CB750 motorcycle in 1969, Honda followed with a string of lighter fours featuring engines as small as 350 cc (CB350 Four, CB500 Four), and the CB400F 408 cc Four, produced in 2 models.

For the most part, the CB400F was simply an upgraded version of the 350 model from the previous year. The most striking change was the swoopy four-into-one exhaust system that snaked around the frame, converging into a single muffler on the right side of the bike. Also noticeable were the angular fuel tank and flat cafe-style handlebars, all of which gave the bike a more racer-like look and feel than the rather pedestrian 350.

Although aimed at the sporting segment of the market, the four-stroke CB400F did not have the acceleration of the competitions two-strokes, particularly the triples from Kawasaki. But what the CB400F engine lacked in power it made up for in refinement, the small-displacement four-stroke being smoother, quieter and much more economical than the two-strokes. To help keep the engine in its power band, Honda employed a six-speed transmission—something of a rarity at the time.

The CB400F was a very successful motorcycle in club or privateer racing. Kaz Yoshima and other racers were able to take Hondas little 408 cc engine up to 490 cc and with the addition of other racer options, this small bore was considered a giant killer.

Confusion often arises over the two models that were produced. Earlier F models had a plain red or blue tank and side-panels running to frame number 1073399. The tanks only bore the words HONDA Super Sport, and the side-panel logo used a font wherein each character was represented by three parallel lines depicting 400FOUR. Up to frame number 1056883 F models had swing-arm mounted pillion footrests, but from then on the F models had the pillion footrests moved to frame-mounted brackets; it is often assumed that this feature only started with the F2 model but this is not the case. The F2 model commenced with frame number 1073400 and featured a new paint scheme: candy antares red or parakeet yellow. The new paintwork featured stripes on the tank and had a different, angular, font for the 400FOUR label on the side panels. The F1 model was not shipped to the United Kingdom or Europe and was a USA/Canada only model. It featured typically a plain yellow tank and black side-panels with the F-type early logo. Today it is not uncommon to see examples restored with F2-type paintwork but F-type logos on the side panels, or F-type early frames with F2-type paintwork.

Further confusion frequently arises in the UK as the CB400F 1975 model was often referred to as the "F1" model.

VIN & Engine ranges (From UK parts list)
CB400 Four Euro Parts list vin range


VIN & Engine ranges (For USA models)
CB400 Four USA vin and engine tables