The Honda CB750F Super Sport

Best bets on tomorrow's classic Honda motorcycles
By Richard Backus
May/June 2010

The Honda CB750F Super Sport.
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Honda CB750F Super Sport
Years produced:
 1975-1978
Claimed power: 58hp @ 8,000rpm
Top speed: 114mph
Engine type: 736cc air-cooled SOHC inline four
Transmission: 5-speed
Weight: 538lb (wet)
MPG: 35-45 (avg.)
Price then/now: $2,152/$1,500-$3,500

The Honda CB750F Super Sport was born out of Honda's desire to regain its position as a motorcycle pacemaker.

When Henry Ford launched the Model T in 1908, there was nothing else like it, and the T established a design template that defined the automobile for more than a decade. The problem? Ford was still building the T in 1928, and the market had moved on. By continuing to manufacture the same basic car, Ford maximized the benefits of mass production, but at the cost of market leadership. After years of snapping at Henry’s heels, the Dodge Brothers, Louis Chevrolet and the rest streaked out front.

Something similar happened to Honda in the 1970s. The 1969 Honda CB750 Four mapped out the future for motorcycles. And like the Model T, it stayed in production for just a little too long.

By 1975, the Kawasaki Z1 with its 903cc DOHC engine had leapfrogged ahead of the CB750. And waiting in the wings were The Suzuki GS750 and the Kawasaki KZ750, both aimed squarely at the market Honda had built, and creating along the way what was to become known as the Universal Japanese Motorcycle or UJM: the air-cooled, 2-valve, DOHC across-the-frame inline four.

Honda’s response to the challenge was conservative. In 1975, the 750 K5 with its distinctive stacked mufflers was joined by the Honda CB750F Super Sport with a sportier 4-into-1 exhaust. The Honda CB750F also wore a new, slimmer-looking (but 0.3-gallon larger) gas tank with a recessed filler covered by a lockable plate, and a disc brake replaced the rear wheel’s mediocre drum brake.

In spite of its radical-looking (for Honda) exhaust, changes to the basic 750 Four plot were minor. Reduced trail and a longer swingarm improved straight-line stability, while a stiffer frame and suspension changes improved handling in the corners. And although the engine was claimed to be unchanged, the new exhaust system brought minor adjustments to valve timing and carburetion, which, according to Cycle magazine, also eliminated the K-bike’s off-idle flat spot.

Whether it was the new exhaust (and revised air box) or some undisclosed engine modifications, the F produced considerably more power than the K-bike. Cycle magazine recorded 58hp at the rear wheel compared with 49hp for the 1973 K3. This, combined with lower gearing, meant a standing quarter in the high 12s instead of the 13s. On the road, the improvements made for a comfortable ride and precise steering: “… it handles better than any of the other Japanese superbikes,” said Cycle. Fuel consumption was slightly worse at 43mpg versus the K’s 45mpg, perhaps because of the lower gearing and a 12-pound weight increase.

Then the 1977 Honda CB750F2 Super Sport, the CB750F2, was introduced in 1977. The F2 featured Honda’s ComStar wheels with dual disc brakes at the front while the 4-into-1 exhaust exited through a new muffler with a slightly deeper exhaust note. Changes inside the engine (larger valves and more radical cams) improved power to around 60hp at the rear wheel, but at higher rpm (now 8,500 compared with the F’s 8,000rpm) and with the redline stretched to 9,500rpm. To emphasize its sportiness, the engine was powder coated black.

At over 540 pounds with a half tank of gas, the F2 was also the heaviest 750 so far (with the exception of the 750A automatic), and 10 pounds heavier than the 4-pipe touring K model. Yet in spite of the extra weight, and the fact that the 28mm Keihins now had accelerator pumps, fuel consumption improved slightly to 45mpg. Most testers considered the F2 to be the best Honda 750 so far, the result of continual refinement and improvement that had created a comfortable, fine handling motorcycle with performance that just about kept pace with the GS750.

All was not perfect in paradise, however. During a 10,000-mile extended test, Cycle Guide’s F2 dropped a valve, destroying a piston and the cylinder head. The cause, they speculated, was insufficient heat treatment of the valve. Testers also emphasized some problems with the 750’s transmission, notably missed shifts, false neutrals and a tendency to drop out of gear. Also noted was a lack of steering stability. The life of a test mule includes some pretty vigorous riding, and the dropped valve occurred after a series of full throttle drag strip takeoffs attempting to verify Honda’s claim that the F2 was capable of sub-13 second standing quarters. “We didn’t abuse the CB750,” concluded Cycle Guide’s review, “but we pushed it to its limits — and then just past.”

Further, the F2’s ComStar wheels — light alloy rims riveted to pressed steel struts — were largely unloved. Honda claimed they embodied the advantages of both cast and spoke wheels without any of the disadvantages. Few liked the appearance of the struts or the rivets, and the latter would prove to be troublesome. Rivets can loosen over time, compromising the integrity of the wheels. If you’re considering buying any Honda with ComStar wheels, check them carefully.

While used Super Sports aren’t exactly rare, good ones are. As the sportiest bike in Honda’s mid-1970s stable, they seem to have received more than their fair share of abuse, victims, perhaps, of over-enthusiastic owners. But parts are plentiful, and thanks to their simple build they’re easy to work on and generally hugely reliable, making them a great usable classic. MC

Read owner reviews of the Honda CB750 Super Sport in the Motorcycle Classics Forum 

4-cylinder rivals to Honda's CB750 Super Sport
1980 Kawasaki KZ750

• 55hp @ 9,500rpm/127mph
• 738cc air-cooled DOHC inline four
• 5-speed
• Disc brake front/disc rear
• 491lb
• 35-40mpg
• $500-$1,500

The 1980 Kawasaki KZ750’s main claim to ascendency was lighter weight. At 491 pounds parked at the curb, it was 59 pounds slimmer than Suzuki’s GS750. Though making just 55hp at the rear wheel, the KZ stayed with the GS on the strip, recording 12.5 seconds at 107mph for the standing quarter. And while conceding outright performance to both the Suzuki and the then-new 4-valve-per-cylinder Honda CB750F (not the 2-valve-per-cylinder 1975-1978 CB750F reviewed above), the KZ750’s light weight also gave it the edge on the track. The secret of the KZ’s performance was its cylinder head featuring ports smoothed with epoxy, which allowed the use of huge 34mm Keihin CV carbs. The engine went into the KZ650 frame, but with 20mm lower top rails to temper seat height. Triple disc brakes provided stopping power.

Testers appreciated the lighter weight of the Kawi, noting that motorcycles in general were getting too fat. The Kawasaki proved to be lithe and nimble with good handling, adequate braking, and decent comfort. While having no particular standout positive attributes, “It’s a motorcycle totally without serious fault,” said Cycle World.

1977 Suzuki GS750
• 60hp @ 8,500rpm/120mph (est.)
• 748cc air-cooled DOHC inline four
• 5-speed
• Disc brake front/drum rear
• 550lb (wet)
• 35-40mpg
• $1,000-$3,500

With the RE5 rotary tanking, the 1977 Suzuki GS750 - the company's first 4-stroke four - had to be right. And it pretty much was. Combining its 2-stroke expertise with lessons learned analyzing the CB750 and the Z1, Suzuki created a high-revving, short-stroke, DOHC 2-valve-per-cylinder engine with a bulletproof roller bearing bottom end.

The 1977 launch bike featured spoke wheels and a single disc brake front and rear, though within two years the specification included cast wheels and dual discs up front. Showing more than 60hp on the dyno, the Suzuki recorded a 12.75-second standing quarter at over 104mph. Docile and tractable on city streets, the engine had something of a split personality: Once the tach hit 6,500rpm, power came on even stronger all the way to the 9,500rpm redline, where it was still making almost 58hp. Peak power came at 8,500rpm.

Testers praised the Suzuki’s handling and lack of steering vagueness, credited to the bike’s rigid frame, needle-roller bearing swingarm and its long, 59-inch wheelbase.

“It is without question the best motorcycle in the 750 class,” wrote Cycle in January 1977. Big Red took note, and responded in 1979 with the 4-valve-per-cylinder Honda CB750.

 


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Post a comment below.

 

KioskGuy_1
5/2/2010 10:23:06 AM
Good article! I'm taking my motorcycle training classes (today) and am in the market for a Honda CB 750. This helps me understand the differences. Thank you!


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