The Honda CB750A Hondamatic

Under the Radar

| November/December 2011

Honda CB750A Hondamatic
Years produced:
Power: 39hp @ 7,500rpm (rear wheel , period test)
Top speed: 97mpg (period test)
Engine type: 736cc air-cooled OHC inline four
Transmission: Two-speed with torque converter, foot shift
Weight: 557lb (wet)
MPG: 45-50mpg
Price then/now: $2,194 (1976) / $1,000 - $3,000

The part of riding a motorcycle that newcomers typically find most difficult is balancing clutch and throttle control when taking off from a standstill. So a motorcycle without a clutch should be a no-brainer — shouldn’t it?

That’s presumably what Honda thought when they brought the Honda CB750A Hondamatic to market in 1976. Superficially, the A model can be thought of as a Honda CB750F with a torque converter and two-speed transmission instead of the regular bike’s five-speed cog box. In practice, though, the 736cc inline four got pretty much a complete makeover.

Revisions to the combustion chambers lowered compression, which, with smaller carbs, camshaft changes and a four-into-one exhaust revised the power curve for more low-down thrust to suit the characteristics of the torque converter. An accelerator pump fitted to the number two carburetor (but feeding all four) helped to alleviate a known flat spot off idle in the standard power delivery of the Honda CB750F. A new Hy-Vo chain drove a jackshaft behind the crank, and powered the torque converter’s oil pump, with gear drive to the two-speed tranny. To provide an oil bath for the transmission and torque converter, the engine’s lubrication was switched from dry to wet sump.

Just two speeds? With the torque converter doing the hard work, that’s all Honda’s suits decided it needed. But while the torque converter replaced the clutch, shifting between the two gears was done manually with a conventional foot pedal. The reason? Honda figured an unexpected shift mid-turn might alarm an inexperienced rider — arguably their target demographic. In any case, the Honda CB750A would comfortably pull away from a standstill in high gear (“drive”): it just did it more quickly in “low.”

For the engine to turn when the starter was pressed, the transmission had to be in neutral. And if you forgot to shift into neutral before parking the Honda CB750A, deploying the side stand would do it for you. Both of these features were obviously intended to prevent unintended launches. Similarly, a push-button parking brake acting on the rear wheel prevented the bike from rolling away if parked on a slope, there being no direct gear linkage between engine and wheels. Even after the brake button was released, the brake remained on and the bike wouldn’t roll until the rider dabbed the brake pedal.

Richard Backus
12/1/2011 10:29:48 AM

Good catch, David. That was an inadvertent error, the result of copying and pasting the wrong tech box. It's fixed now and correct, as it ran in the magazine. Richard Backus/Motorcycle Classics

David Simmonds
12/1/2011 7:41:12 AM

Who does your proof reading? The info listed for the 750A is totally incorrect. For openers, it's a '78 , so it couldn'y have been manufactored in 1983-84. The engine is 743cc NOT 798. I love the articles, but you need to make sure you publish the correct specs. OR not at all.

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