Doug Young has a shed full of classic Honda CB400s. Nothing too unusual in that, you might think, but it turns out they're all a rather curious breed of classic bike...

Back in last November's magazine, we featured a Moto Guzzi V1000 Convert with (sort of) automatic transmission. At the same time, we couldn't resist the temptation to have a look at Honda's stab at giving up gear shifting.

These days, so many scooters have automatic transmission that we don't blink twice at it, but it's taken a while to get the system to a workable format. The original idea was that it would make motorcycles much easier to ride and so open up a whole new potential marketplace. BSA, Jawa and Zenith all experimented with forms of automatic transmission over the years and then Guzzi and Honda took up the challenge.

The Hondamatic CB750/4 first appeared in 1977, with a foot-operated gear lever to select neutral, low or high ratios. Low ratio would carry the rider smoothly to 60mph before switching to the high ratio - although you could pull away in high ratio with no problem although progress was leisurely. The bike was detuned from 65bhp to give 47bhp at 7500rpm, and ran lower compression (down from 9:1 to 7.7:1) than the standard model. There was no hand-operated clutch and instead a torque converter, very similar to the one used in the Civic, shouldered the load. A centrifugal hydraulic pump was driven by the engine and threw streams of oil at a veined turbine wheel. This wheel in turn drove the gearbox shaft and the oil drained back to the centre of the pump to be re-circulated again.

Effectively the 750 was a semi-automatic because the rider still needed to shift manually between high and low ratios, but it was more hampered by a lack of overall oomph than any problems with the transmission. It cost as much as a standard 750 but topped out at around 105mph at a time when its competitors were nudging 120. Around 9000 CB750 automatics were sold when the model was discontinued in 1978.

One of the machines I own has been featured in print (under the title 'Automatic Dream Machine'). I got quite a bit of paperwork with this Auto which included a letter, written in 1983, from Brian G Thompson, the Founder and Acting Secretary of the Hondamatic 400AT Owners' Club. Can you believe that someone started a Club for the Automatic just as they were disappearing? The reason I mention this letter is because he said that Honda UK sold a meagre 1000 Hondamatics!

He also mentioned that the generators had a habit of burning out. I have had first-hand experience of this. On two of the machines I bought, the owners had tried to fit a CB400T generator and stator which does not work with the Auto. The reason they will not work is because of the higher revs of the Auto. The pulse pick-up on the generator rotor has two pick ups to coincide with the gear change, whereas the manual engine only has one pick up pulse. The proper generators are like hen's teeth to get hold of.

Apart from that, the Auto 400s are reliable and the rear chain lasts longer than on a manual because you don't change gear as often.

The Hondamatic came in three colours: royal blue, orange and wine. I regret that I sold the wine one that I had (I think it was to a guy from Oban) So if anyone out there has a wine one please feel free to contact me on 01383 413440…