Honda CB750A: Honda's Automatic Motorcycle
By Ian Lee
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.
In regards to the fuel system, the standard CB750 fare was not going to suit the Hondamatic. Four 24mm slide/needle Keihin carbs are fitted, along with an accelerator pump so when the bike is accelerated from idle it does not suffer from the “Honda Burp” of the period. On top of this an electronically controlled diaphragm on the throttle linkage automatically bumps up the revs as soon as the transmission is engaged to make sure the bike doesn’t stall. Breathing out is taken care of by a 4-into-2 exhaust system, the silencers swept up and back in the custom style of the time.
Aesthetically, the Honda CB750A looks very different to the other CB750 models, the designers looking to the GL1000 for inspiration. GL-style rims are fitted front and rear, a 19.5 litre GL-styled tank is fitted, and the handlebars are high and wide. The larger GL rims give more ground clearance, but they also make the bike look bulkier than it really is. Stopping duties are covered by standard Honda fare, disc in the front, drum in the rear. The front caliper is slightly different to standard CB spec. A road test of the period rates the rear drum as adequate and the front disc as “not being the best disc brake, but for the design of the bike it works well.”
Instruments are basic, the tachometer making way for a large light readout showing whatever gear the bike is in at the time. The speedometer gives the range for both low and drive gear to ensure the rider does not overwork the engine. Drive gear is good from 0 up to 100mph, the low gear being only from 0 to 60mph. Although it is possible to use high gear all the time, using low gear in traffic is the better option, leaving drive for the open road. A large 20-amp hour battery takes the traditional place of the Honda oil reservoir, fed by a 290-watt alternator. Kickstart is in case of emergency only, with a kickstart lever mounted under the seat in.
The Australian Automatics
In early 1977 Bennett Honda, Australia’s Honda motorcycle importer, brought in two California-spec CB750As for evaluation in regards to selling them on the Australian market. These bikes were given to local motoring journalists on the proviso that no one was to write up a road test. One magazine broke the pact, and published their thoughts on the CB750A. This prompted Honda Australia, who had taken over from Bennett in importing bikes, to release the bikes for a second full road test. This time journalists would be allowed to do a full review and publish their view of the automatic motorcycle. This was all for naught, as in the end Honda Japan decided that it would be a waste of money to specify such a small batch of bikes to sell on the Australian market, and the two test bikes were the only CB750A bikes brought into the country by Honda.
After Honda Australia gave up on the idea of importing CB750As into the country the test bikes were sold to Jim Airey’s dealership in Sydney. One of the Hondamatics was purchased by a local car dealer, who painted it white. It was stolen not long after and hasn’t been seen since. The second test bike found its way into the hands of the current owner, who after 35 years is still happy with the purchase. Modifications over the years include an oil cooler, lower handlebars for better riding position, and the original exhaust pipes put away for safekeeping. The only other noticeable modification is the retrimmed seat; foam doesn’t last forever and this bike has racked up some miles.
The bike being California spec, the indicators and headlight come on as soon as the ignition is turned on, not something you normally find on bikes in Australia. The bike looks immaculate for all its years, looking no worse than pictures of it taken for a magazine review in late 1977. This CB750A is definitely no trailer queen, either; if it goes somewhere, it is under its own power, and the owner likes to take it out at least once a month to stretch it’s two-speed legs. This remnant of an attempt to produce a whole new class of motorcycles is in good hands, the owner showing it is possible to have a rare bike and not hide it away in the garage under a cover.
Ultimately, the automatic motorcycle craze did not take off. The CB750A was classed as too heavy for novice riders and too slow for experienced riders. The bulk of the transmission worked against both classes of riders, leaving the over-engineered CB750A without a demographic to sell to, thus prompting its demise in 1978. Interest in these Hondamatic models is rising, with riders realizing they aren’t bad bikes per se, they just require a different riding style. It’s good this CB750A has found its way into the feature bike owner’s hands and that he is willing to show it off. Or to put it in Motorcycle Classics terms: To ride it, not hide it.
Thanks to the owner of the bike for his time and information. Also to Tom Day and Stewart MacDonald for their assistance researching this piece.
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