The Honda CB750A Hondamatic

Under the Radar
By MC Staff
November/December 2011
Add to My MSN

An old Honda advertisement for the Honda CB750A Hondamatic.
MC Staff
Slideshow


Content Tools

Related Content

1978 Moto Guzzi 850 Le Mans

A 1978 Moto Guzzi 850 Le Mans on display with other classic motorcycles at the Barber Vintage Motors...

Motorcycle Classics at Motogiro America - Day 4

Yesterday was day four of the Motogiro America, and Dave Miller, who’s riding for Motorcycle Classic...

Mikuni Carburetor Mixture Setting

Motorcycle Classics’ tech expert Keith Fellenstein gives advice on setting the fuel/air mixture scre...

Motorcycle Classics at Motogiro America

If you're like, oh, about 99.9 percent of classic bike fans, right about now you're probably wishing...

Honda CB750A Hondamatic
Years produced:
1976-78
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.

Instruments were also different on the Honda CB750A Hondamatic. No tachometer was fitted, although the speedometer showed the maximum speeds in low and drive, 60 and 105mph, respectively. Idiot lights indicated low, drive and neutral, as well as more usual functions like oil pressure, high beam and turn indicators.

More detail differences came in a wider rear tire on a smaller rim (4.5 x 17in vs. 4 x 18in), with both front and rear using alloy rims, as well as bigger fenders. There was also a new gas tank, seat and side covers, and an upgraded 290-watt charging system fed a larger battery with a bigger power reserve.

But how did the Honda CB750A work? Although overall performance was less brisk than the F model, testers found the A still swift enough to leave most other traffic behind on acceleration, while not having to pause for shifting — which also meant they were able to pay more attention to city traffic. Also on the plus side was a complete absence of transmission “snatch” and — surprisingly — better ground clearance than the F.

On the downside, performance was definitely compromised, with the A struggling to reach an indicated 100mph and giving away two seconds in the standing quarter. And while some testers thought the gearing seemed too low, they also missed the ability to shift down a couple of gears for assertive passing.

Overall, the A seemed to work best if left in low gear in the city and high (drive) on the highway — though low was also considered useful on tight mountain roads.

Cycle World ran a side-by-side comparison of the 750F and A in its September 1976 issue and concluded that rather than a learner bike (too big and heavy), the A would appeal instead to older, more experienced riders looking for a sophisticated ride, and speculated that a mid-size Honda with the torque converter tranny might be a better bet for beginners. (Like a 400, perhaps ... ?) But appeal it did not, and it was dropped after two years.

Honda tried the “Hondamatic” idea again with the Honda CB/CM400A (see below), but it didn’t fare much better.

Contenders: Automatic Options to the Honda CB750A Hondamatic 

Honda CB400A and CM400A
• 43hp @ 9,500rpm/93mph (claimed)
• 395cc air-cooled, SOHC parallel twin
• Two-speed with torque converter
• Disc brake front, drum rear
• 411lb (wet)
• 45-55mpg
• Price now: $1,000-$2,000

Just as Honda was preparing to drop the Honda CB750A Hondamatic, it introduced the smaller, new-for-1978 Honda CB400A Hawk Hondamatic. Similar in most respects to the new five-speed CB400T1, the A used smaller carburetors (28mm instead of 32mm), with accelerator pumps to combat any off-idle leanness. Like the CB750A, the CB400A’s transmission used a fluid-coupled torque converter and two-speed gearbox selectable by a foot lever.

The engine for the Honda CB400A and CM400A was a 395cc 360-degree parallel twin with 3-valves per cylinder and a single overhead camshaft. First-year CB400As had a flat seat, while CM models (1979-1981) suffered from the era’s “custom” styling, sporting steeply stepped seats, shorty mufflers and two-tone paint jobs. All A models rolled on Honda’s controversial Comstar wheels.

Like the CB750A, performance was compromised by transmission losses, but the CB/CM400A was still the equal of most cars in the city. Honda sought to dispel performance concerns by advertising the CM400A’s standing-quarter time as “quick as a Porsche 924.” Nevertheless, it faired poorly amongst its rivals, being more than two seconds slower in the quarter mile than the Suzuki GS400, while its stable mate, the standard-shifting CB400T1, was three seconds and 11mph faster — and $300 cheaper.

Even so, owners swear by them, and they’ve achieved a certain level of cult status for their longevity and reliability.

Moto Guzzi Convert 1000
• 71hp @ 6,500rpm/110mph (claimed)
• 949cc air-cooled OHV 90-degree V-twin
• Two-speed with torque converter and clutch
• 503lb (dry)
• 35-45mpg
• Price now: $2,500-$5,000

Arriving just ahead of the CB750A, in 1975, the Moto Guzzi Convert 1000 also used a fluid coupled torque converter driving a two-speed gearbox. But unlike Honda’s automatic, the Guzzi had no neutral gear, so it retained a conventional clutch for starting and for shifting between low and high. Derived from the 850T3, the Convert used the engine from the 1000SP in Lino Tonti’s famous dual loop frame, and came ready equipped for touring with hinged rubber floorboards, hard saddlebags and a large windshield. This was no entry-level machine, but a fully-loaded, long range tourer — though later models nixed the panniers, floorboards and windshield.

Guzzi handled the problem of unintentional roll-offs with an ingeniously simple device. Whenever the Convert was parked, the load on the side stand was transferred to the rear brake by a bell-crank linkage, thus applying the brake. It was simpler than Honda’s push button lock, but just as effective. Further, the Guzzi’s engine wouldn’t start unless the clutch was pulled in.

When Rider magazine collected their Moto Guzzi Convert 1000 test bike in 1976, the Guzzi distributor told the tester to think of it as “the Checker Cab of motorcycles” — solid, comfortable, but not very pretty. The tester agreed, but added, “It’s much more fun.” Produced through 1984, Converts are an inexpensive — and reliable — route to MG ownership today. MC 


Previous | 1 | 2 | 3 | Next






Post a comment below.

 

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.








The sound and the fury: celebrate the machines that changed the world!
First Name: *
Last Name: *
Address: *
City: *
State/Province: *
Zip/Postal Code:*
Country:
Email:*
(* indicates a required item)
Canadian subs: 1 year, (includes postage & GST). Foreign subs: 1 year, . U.S. funds.
Canadian Subscribers - Click Here
Non US and Canadian Subscribers - Click Here
 

Motorcycle Classics is America's premier magazine for collectors and enthusiasts, dreamers and restorers, newcomers and life long motorheads who love the sound and the beauty of classic bikes. Every issue  delivers exciting and evocative articles and photographs of the most brilliant, unusual and popular motorcycles ever made!

Save Even More Money with our RALLY-RATE plan!

Pay now with a credit card and take advantage of our RALLY-RATE automatic renewal savings plan. You save an additional $4.95 and get 6 issues of Motorcycle Classics for only $24.95 (USA only).

Or, Bill Me Later and I'll pay just $29.95 for a one year subscription!