Honda's Cammy Cub: 1964-1969 Honda S90

Comparing the Honda S90 with its primary competitors, the Suzuki K11 Sport 80 and Kawasaki J1.


| September/October 2017



Honda S90

Photo courtesy Honda

Honda S90
Years produced:
1964-1969
Power:
8hp @ 9,500rpm
Top speed:
62mph (claimed)
Engine:
89.5cc air-cooled OHC single
Transmission:
4-speed gearbox, chain final drive
Weight/MPG:
176lb (dry)/70-90mpg
Price then/now:
NA/$700-$3,000

In the beginning came the Cub. Honda’s most easily recognizable motorcycle first hit the streets of the U.S. in 1958 and was an instant success, selling 24,000 units in its first five months. And while the step-through, 3-speed 50cc Cub worked perfectly for urban commuters, motorcycle enthusiasts, especially in the U.S., wanted more. Honda’s twin-cylinder range of CA touring and CB sport bikes was well established by 1964, but there was room in the market for something between the Cubs and the twins. Enter the Honda 90.

The first 90, the C200, arrived in 1963 with an iron cylinder and head, pushrod valve operation and a conventional 4-speed transmission instead of the Cub’s 3-speed automatic clutch unit. It also looked more like a traditional motorcycle, though with a pressed steel spine frame. Then in 1964 came the sporty S90 with an all-alloy engine and overhead camshaft.

Honda wasn’t the first motorcycle manufacturer to produce street bikes with overhead camshaft engines, of course, but Big Red did take them fully mainstream. The advantages of the design — a lighter, more direct valve train — meant Honda’s engines could be tuned for more power at higher revs, also making them more efficient. The downside was that overhead cam engines were typically more expensive to manufacture and valve clearances more difficult to adjust. Honda’s innovative design used a single chain-driven camshaft in the cylinder head operating the valves by a pair of rockers. Each rocker had a screw adjuster for straightforward valve adjustment.

The S90’s “over-square” (50mm x 45.6mm bore and stroke) 89.5cc engine was arranged with its iron-lined alloy cylinder almost horizontal, and capped with a light alloy cylinder head containing the single camshaft. The built-up crankshaft ran on two impressively large ball main bearings with a caged roller bearing big end. The “wet” sump held a quart of oil, which it kept clean with a centrifugal oil filter. Drive to the wet mutliplate clutch was by gears, passing from there to a 4-speed constant mesh gearbox with left side foot control (one down, three up). Final drive was by chain. Claimed output was 8 horsepower at 9,500rpm — an impressive rate compared with most of its contemporaries.

The compact drivetrain was bolted to a pressed steel beam frame. Front suspension was by hydraulically damped telescopic fork, with a swingarm with two spring/damper units at the rear. The chassis ran on 18-inch wheels front and rear, both with 2.50 x 18-inch tires and single-leading-shoe drum brakes. Ignition was by coil fed from an alternator and a 6-volt, 6-amp-hour battery, which also powered the lighting and other electrics. Slender, contrast-colored fenders and a streamlined gas tank with chrome side panels completed the sporty look. The list of standard equipment was impressive for a small bike, too, and included a large, replaceable-element air cleaner, turn signals, a tool kit stored under the seat, dual mirrors and a passenger grab strap. Although no tachometer was fitted, the maximum speeds in each gear were marked on the speedometer.





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