Honda CB750A: Honda's Automatic Motorcycle

| 2/7/2013 2:25:57 PM

Tags: mc dispatch, classic honda motorcycles, classic japanese motorcycles,

Honda CB750A: Honda's Automatic Motorcycle 

Hondamatic. To most Australians it is associated with the Honda automatic cars that were sold in the country in the late 1970’s and early 80’s. It seems a little known fact in Australia that Hondamatic is also the term given to Honda motorcycles equipped with automatic transmissions, and that Honda attempted offering these automatic motorcycles to the Australian bike riding fraternity with no luck. The feature bike in this article is a relic from this era, a California-spec CB750A brought to Australia for testing in the local conditions. Even though Honda Australia decided against selling the model here, the bike stayed, and has found its way into safe hands. 

At the start of 1977, Honda was producing two automatic motorcycle models: The CB400A, known in the U.S. as the Hawk, and the CB750A, a reworking of the CB750F. These bikes were initially conceived as a way for learner riders to get comfortable riding motorcycles without fear of stalling. This allowed for the novice to practice staying upright, braking and riding in traffic, all without having to focus on changing gears constantly as well.

I say changing gears constantly because the automatic transmissions offered on Hondamatic motorcycles were not automatic in the true sense of the word. A shift lever in the same position as a gear changer on a manual Honda allowed the rider to shift between neutral, low and drive. The ability to manually shift between high and low made sure the bike wouldn’t shift gears through a corner, throwing a rider off balance. Also built into the automatic models was a linkage from the kickstand to the gear lever, so when the kickstand was operated, the bike would put itself into neutral. This would stop the bike from starting in gear, something someone new to riding might overlook after getting back on the back.

The automatic motorcycles lacked the performance of their manual brothers. Quarter-mile times and top speeds were slower, the added weight of the transmissions not helping. The CB750A didn’t allow enough acceleration on the downshift to pass cars, and the CB400A transmission allowed too much chance of over run when heading into corners at speed. Performance issues and a change in the demographic of bike buyers meant Hondamatics only got a 3-year run before being dropped from the lineup.

In an engineering sense, the CB750A wasn’t just a CB750 with an automatic transmission fitted. Much work went into this model to make them stand apart from their CB750 stable mates. The engine gained different rocker covers and crankcases to suit the different engine/transmission combo. The engines were changed from dry sump to wet sump, the same oil going from the torque convertor through the engine to be cooled. The torque convertor is of the same design as the Civic cars of the time, as well as the Moto Guzzi V1000, which would have been a competitor to the CB750A. A three-part unit, the convertor was made up of a centrifugal oil pump, a turbine wheel and a stator. The oil pump, driven off a primary drive connected to the crank, would spin inside the turbine wheel, both of these components being bowl shaped. The oil from the pump would travel along the vanes of the turbine wheel, where it is then directed to the cup-shaped vanes of the stator wheels, and deflected back to the oil pump hub. Simple but rugged, the Hondamatic motorcycles gained a name for reliability that still stands today.

Carl Neal
8/1/2013 7:37:34 AM

I bought a new 750 hondamatic. Loved it. But it had one flaw that could have been corrected by Honda. At slow speed, making a left turn, with my right foot on the ground. If I had to stop using the front brake, that automatic transmission just pushed me over. And i couldn't do a thing about it. My right foot could not get to the brake. Glad i installed crash bars on it. The fix could have been the addition of a hand brake on the right bar to control the rear wheel. Oh, and the gas milage was terrible

Kim Gilsbach
2/25/2013 2:40:08 AM

I have a 1976 750 that runs quite well with 29000 miles. Bought on ebay and found a few replacemnet parts. Appears to be all original. The tank is rusty, so I sealed. Fun to ride on ocassion. Interesting that I was approached from a guy in Australia about buying it.

Bill Revene
2/14/2013 7:32:23 PM

I was selling Honda motorcycles when test automatics came out. We had two of each, the 400 and 750. We were only able to sell one of each as they were neither fish nor fowl. The experienced riders wouldn't consider a "scooter" type non-shifting and the 750 was too big for an entry level rider to consider. Back then an entry level bike was a 250 or 400. The 750 was the big kid's bike. One person that bought the 750 just didn't want to shift and thought it was unique. The person that bought the 400 did a lot of driving in Boston and thought the automatic would be easier. I'm not sure what happened with the 2 unsold bikes as it was seasonal work for me.

Jerry Griffin
2/14/2013 7:01:39 PM

Good article even with a few discrepancies. Thanks for posting Richard.

Jerry Griffin
2/14/2013 7:00:21 PM

Bill and Sam have been kicking some serious racers asses with their A. It's a blast to see the other racers snicker when a 35 year old old school 750cc motorcycle with spoke wheels pulls up in staging with a crew only to be abushed at 1320' and sent home.

Harold Bevins
2/14/2013 5:57:01 PM

I have one of these 77 Honda 750A's in my garage, but it needs a lot of work to restore it. I would sell it for 100.00 if anyone is interested. But just so you know it does not tun, and it has lots of rust on it. I also do not have all the parts, although there is enough to make it a running machine. if interested. I'm in Dayton Ohio.

Bill Benton
2/14/2013 4:06:21 PM

We drag race one still.Sam Green and me(Bill Benton). Stock rwhp 38.9 our last dyno run was 87.07!! 12.18 @ 116.xx. Check it out at forums high performance Section. Bill

2/14/2013 3:22:22 PM

i agree with raymond about in accuracies within the article . don't know about aussie land but the cb750a came out in the US '76 . the only similarities with the cb750f was the exhaust which actually had an F part # . that was changed to 4 into 2 in '77 . all top end were enterchangable between the A /F/K models . but the a had lower compression pistons , milder cam and smaller carbs . even the valve cover was the same with the exception of a plug where the tack drive was on the F and K . the A had it's own frame which had no components that fit the F or K . i could go on but i'm dure you get my point . also as far as i know the cm400a came out in '80 and ended as the cm450a in '84 . don't have the honda ID guide with me at present . i owned a very nice '77 model with a complete K model top end and better carbs . lots of fun . other wise thanks for an excellent vintage motorcycle magazine that this moto gearhead just loves .....

Peter Davidson
2/14/2013 2:35:40 PM

I own a 1977 Honda CB750A in my collection, it's a lot of fun to ride has less than 5,000 miles on it. I'm the third owner of the bike. I was lucky that the two past owners had kept it in a garage out of the weather. The gas tank had no rust in it and only needed tires, oil change and carbs cleaned. The owner had had a tall sissy bar with carpet on the back with metal scroll work. He hated it and took it off, I took it apart cleaned it up and installed back on the bike. Real Retro!

Raymond Rexroad
2/13/2013 2:29:17 AM

A number of inaccuracies in this post. If this makes it into the mag, they need to be corrected!

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