Retrospective: 1983-1985 Honda CB650SC Nighthawk

1983 Honda CB650SC Nighthawk
1983 Honda CB650SC Nighthawk. Owner: Bob Duncan, Atascadero, California.

This Nighthawk was truly a marvel of good looks and efficiency when it appeared in 1983. Good lines, good paint, cast alloy wheels, megaphone-styled exhaust and 65 horses out of an all-new 655cc in-line four. This middling-sized engine sported 16 valves, two overhead camshafts and hydraulic control of valve lash. With six gears connected to a trouble-free shaft drive. It seemed that checking tire pressures, occasionally changing the oil and keeping the bike looking shiny was all the maintenance an owner had to do.

“But wait!” cries a somber voice from a dark corner of the library. “Honda’s own ‘Motorcycle Identification Guide’ says there was a 1982 CB650SC as well.” Truth. So maybe we better start a little earlier. Like back in 1979, when the Japanese manufacturers were still wondering about what cylinder sizes sold best. Since the old Brit-bike 650s had sold well and were quite popular, the Big Four (Honda, Yamaha, Kawasaki, Suzuki) were all offering 650s—twins and fours. Honda came out with a very nice CB650C four-banger, 627cc, with single overhead camshaft, two valves per cylinder, and five-speed gearbox with chain final drive.

1983 Honda CB650SC Nighthawk
Just look at that ’80s-awesome dash!

After three years the marketing department felt the model needed a little more pizzazz. And a catchy new name—Nighthawk. But this 1982 Nighthawk used the old CB650 engine and chassis, with a new tank, bodywork and saddle. Would the new name and styling work?

No time to find out, really, because within a year an entirely new CB650SC Nighthawk appeared, which had obviously been in the planning when Honda gilded the old CB650 lily for the 1982 model year. It actually seemed that this was not a smart move, because the minor attention given to the styling gave the alphanumeric designation a hint of boredom. However, the 1983 model put the lie to that, getting rave reviews from everyone, everywhere.

1983 Honda CB650SC Nighthawk
Dual slash-cut chrome pipes looked sporty.

As noted in the opening paragraph, the new 650 doubled the number of camshafts and valves. Each of the four cylinders had a slightly oversquare bore of 60mm, stroke of 58mm. For those interested in the minutia, the valves had an included angle of 38 degrees, with the intakes (28mm) enjoying 18 degrees, the exhausts (22.5mm), 20 degrees. For the average layman, these are just numbers, while for the engineer, these are essential for maximizing intake and output charges. And Honda made sure that the critically minded (motojournalists) knew all about this. Fuel was fed in via four 29mm Keihin CV carburetors.

The starter (operating through a self-adjusting chain running to the crankshaft) and alternator (discreetly cooled by a fan) were mounted behind the cylinders in order to minimize engine width—which was 16 inches, almost four inches narrower than the previous 650. Nothing stuck out to touch the ground should a sporty type want to see how far he could lean—unless he fell down. Another self-adjusting chain (getting rid of another onerous task) ran up between cylinders two and three to spin the cams. The crankshaft was one piece, and off the right end was the rotor that triggered the electronic ignition…all done with magnets, wrote one humorous reporter.

1983 Honda CB650SC Nighthawk
The Nighthawk had dual front disc brakes and cast mag wheels.

Primary drive was via a big sprocket (54 teeth) that sat at the left end of the crank, which spun an even bigger sprocket (92 teeth) inboard of the wet, hydraulically operated, six-plate clutch. The rider had a choice of six well-thought-out gears, which transferred power to the rear wheel via a shaft. After shafting the Gold Wing and the CX, Honda felt that this useful bit would be quite popular.

The drivetrain sat in a full-cradle, tubular steel frame—and was rubber mounted. Those annoying 10,000-rpm vibrations could barely be felt, leaving the rider to happily spin the motor up to redline. Showa supplied the suspension, with a 39mm fork up front, without air-assistance. However, the height could be slightly adjusted by adding air, while changing oil weight could alter the damping qualities. Rake was 28.5 degrees, trail, 3.9 inches.

A long, almost 20-inch, box-section swingarm ran out to a pair of shock absorbers that offered both rebound and compression damping adjustments, along with five spring-preload settings. Heavier riders complained about the shocks being too soft. “Go on a diet,” was the dealer response. Handling also suffered a bit due to the up and down jacking activity of the shaft, but only the sportiest of riders would find serious fault.

1983 Honda CB650SC Nighthawk
The Nighthawk was a surefire winner, and the name was resurrected in 1991.

The 19-inch front wheel carried a 100/90 tire, and two disc brakes with twin-piston calipers, providing excellent stopping power. The rear 16-incher had a 130/90 tire and a drum brake. Wheelbase was a shortish 57.5 inches.

It had performance, handling, styling, a 12.5-second quarter-mile time and a price of $2,800. Honda was sure it had a winner.

It did…in Europe. But less so in the U.S. The European rider tended to be more practical, and his motorcycle was usually his only transportation. But Americans were more focused on style rather than function, and were looking for very sporty bikes, or touring models, or the ever-popular cruiser. And in ’83 Honda was also offering the Interceptor, the Gold Wing and the Shadow. This “standard” did not cut the old Grey Poupon for the U.S. buyer.

We should note that Honda spread the Nighthawk name over a rather wide range of models, from the CB450SC 447cc parallel twin to the CB750SC 749cc in-line four. However, all Nighthawks were gone by 1986—only to have the name resurrected in 1991.

1 COMMENT

  1. Man Oh man, I loved my ’83 Nighthawk 650! rode it 22 years, practically maintenance free. (except for normal oil change, spark plugs, brake pads, tires) I sold it and it still looked and rode great, but I wanted something with a longer wheel base that didn’t bump around my now somewhat aging bones. The young fellow who bought it, could not believe his luck. I miss that 6th gear!

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