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Retrospective: Honda CB750F Super Sport (SOHC): 1975-1978

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

Photo Credit: Clement Salvadori

Clement Salvadori
January 21, 2006
Filed under Honda Motorcycle Road Tests: Reviews on Honda Motorcycles, Retro + Vintage Motorcycle Reviews

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(This Retrospective article was published in the January 2006 issue of Rider.)

Here was an immensely successful exercise in styling. For six years Honda had been selling the CB750K, a superbly technical motorcycle with such innovations as an electric starter and disc brake, but low on looks.

Undoubtedly there were some who liked the somewhat plain four-piper design, but the Honda marketeers were quite aware that a sporty image was the coming thing. The Italians had “go-fast” built into all big bikes, the Germans had even made the R90S look pretty dashing, the Brits still had sportyish Triumph twins and triples, as well as the Norton Commando, and even Honda’s rather stodgy Japanese competition was enjoying speed fever. When Suzuki’s two-stroke triple Water Buffalo was getting higher marks for performance than the K, something needed to be done.

The aftermarket people were already onto the sporting look. The Vetter Corporation was selling a lovely Rickman frame which would accept a CB750, or Kawasaki Z-1, engine. Anyone just wanting to look fast could call Pichler or Dunstall and buy a slick fairing. No point in giving all that money away to the competition, said the Honda honchos, let’s go sporty, let’s build the 750F.

But what did the F stand for? Fast? Four-into-one? Actually, the F suffix had originated in 1972 with the CB350F—F for four cylinders, so as not to be confused with the CB350K twins. But why did the twins get a K suffix, when the original K appeared on the 1969 CB750 four-banger? Never mind.

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

The year 1975 saw the introduction of three F models, the 400F, the 550F and the 750F. That 400F was truly trick, with mildly set-back footpegs, a flat handlebar and a lovely megaphone-styled exhaust. However, the company decided to go the conservative route with the 750, apparently more concerned with bringing four-piper types into the sporting world than with luring crossover owners from the Ducati realm.

This is partially a retelling of the making of the most significant motorcycle of the last 50 years, but it is a story worth hearing again. There was nothing new about disc brakes, electric starters and overhead camshaft, transverse-mounted, four-cylinder engines in 1969—just that Soichiro Honda had made them cheap and reliable. The CB750K was a winner from when it left the starting gate, but everybody knew that winners get old.

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

Which is when the styling artists got their orders. The K was OK, and would remain the mainstay of the lineup, but something snappier needed to be on the showroom floor. Not too snappy, mind you, not like a Laverda 750SF nor an MV Agusta 750S, but something to provide at least the image of snappiness.

Call down to the muffler department and tell them to make a four-into-one exhaust system. Have the sheet-metal guys stretch that gas tank out a little, not much, just a smidge to give it a slightly elongated, racy appearance; and hide the gas cap. Then tell the seat people to make a little fiberglass extension to fit the back of the saddle, sort of a faux bum-stop that some single-seaters had. The fast look was born.

Of course the frame and engine departments were given their chores. The chassis mathematicians figured that Super Sport riders would go a little faster than those on the standard K, so they gave the fork an extra degree of rake, to 28 degrees. Along with 3⁄4-inch more trail. And left those ugly gaiters off. Built a slightly longer swingarm, which added up to a 57.9-inch wheelbase, 6⁄10-inch longer than on the K. This meant that when the F rider was trickling along U.S. 2 in North Dakota at a modest 100 mph, the bike was reasonably steady.

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

Power was another matter. Honda did not necessarily like to advertise horsepower ratings, but dynamometers don’t lie—unless they are hopelessly miscalibrated, in which case it is not lying. The F put out a good 10 percent more ponies than the K, and while some of those 58 horsepower, at 8,000 rpm, could be attributed to the freer flowing qualities of the four-into-one exhaust, the rest came from a slight boost in compression ratio, using domed pistons, up from 9:1 to 9.2:1. And the timing specs on the valves had been altered to adjust to the new exhaust. Also the carburetion was cleaned up a tad, in those halcyon days before the EPA, with the best of intentions, made a botch of things.

The F, with a full 4.8 gallons of high test in the tank, registered slightly over 535 pounds on the scale. Which was 10 pounds heavier than a K, although the F had three less mufflers. Possibly a little extra metal had been included in order to strengthen the double-cradle frame, with triple tubes, a main and two auxiliaries, running under the tank.

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

Put the leg over the saddle, and the rider sat pretty high at 32 inches. Pull the choke on those four 28mm Keihins, turn the key, and choose between pushing the button or kicking the starter; 999 times out of a thousand, the button won. Vrooom! The muffler had a mellow, unobtrusive sound, the engine warmed quickly, and the rider was away.

Twenty miles down the road, the Bridgestone Super Speeds were heated appropriately, and the twisties began. Tire technology was still pretty basic 40 years ago, but the 18-inch rear and 19-inch front spoked wheels each had a disc. Hit that first sharp left hander at a rapid speed, and the F felt really good. However, coming back at the same speed, the corner now a right hander, there would be a Grounch! as the collector box located beneath the right footpeg touched down. A little help could be had by getting out the toolkit and maximizing the preload on the shocks, but even then, a 200-pound rider was going to mar the chrome. The owner of this CB750F has changed the shocks to S&W, a distinct improvement.

1978 Honda CB750F Super Sport.

1978 Honda CB750F Super Sport.

Other than that minor drawback, the F did live up to its sporty intent. It probably was the best-handling of the Japanese 750-plus fours of the time. And got better. In ’77 the F got Comstar wheels, and a restyled exhaust, with the collector better tucked away, and the muffler now a megaphone look-alike. Also, the engine was painted black, which gave it a more sinister look.

We’ll leave this CB750F after 1978, as for ’79 Honda revamped the whole notion, introducing the double-overhead-camshaft 16-valve engine, and a four-into-two exhaust. In 1983, taking sport design to a new level, Soichiro Honda introduced the VF750F—full of surprises, that man was.

Comments

One Response to “Retrospective: Honda CB750F Super Sport (SOHC): 1975-1978”

  1. tony camberos on September 11th, 2013 9:06 pm

    busco kit de juntas del motor y bomba de frenos de la rueda tracera, me urge!!! para motocicleta honda 1978 four sport

    [Reply]

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