Using 50W Zener to regulate motorcycle alternator?

[2wheelsenough]

I have read with interest the large amount of feedback you have had for this problem.
I have a 1950’s 6volt Enfield that gave me over charging problems when changing to a sealed lead acid battery.
I used a clipper circuit to chop the AC at 7.3 volts. It works ok but 2 x 2n3055 and 2 large diodes clipping each half of the waveform makes for a large unit.
I worry that some of the suggestions you got would introduce a drain on the battery when the bike is stopped and wonder if your final solution gave problems with flat batteries, not a god thing for gel batteries.
2wheelsenough

 

[tylernt]

No battery drain while the bike was off, but I put it into a circuit switched with the ignition.

Sadly, the zener didn't seem to do anything. System voltage still rose above the zener voltage when the engine was revved. Dunno if I killed the zener when I soldered it or if I just have a bad connection somewhere.

 

[Mr RB]

Zeners have a soft "knee" so their voltage will rise with higher currents. That's all normal.

Have you considered ringing a motorcycle wrecking yard? They usually have lots of little regulators pulled from 6v and 12v motorcycles. You can probably also buy one cheap and new on ebay.

 

[2wheelsenough]

Hi tylernt
It sound like you had a faulty zener or it wasn’t up to the job.
My 1950’s 6volt Royal Enfield had magneto ignition so no ignition switch to prevent battery drain, hence the clipper circuit.
What solution did you end up with?

 

[Nigel Goodwin]

Hi tylernt
It sound like you had a faulty zener or it wasn’t up to the job.
My 1950’s 6volt Royal Enfield had magneto ignition so no ignition switch to prevent battery drain, hence the clipper circuit.

Wouldn't it have had a dynamo rather than an alternator as well?.

 

[2wheelsenough]

Wouldn't it have had a dynamo rather than an alternator as well?.

No In the 50’s lots of British bike used magnetos with alternators as Mr Lucas produced them cheaper than dynamos. Also in those days you could leave your bike without it being stolen so no requirement for ignition switch or fancy security systems!!!

 

[Nigel Goodwin]

No In the 50’s lots of British bike used magnetos with alternators as Mr Lucas produced them cheaper than dynamos. Also in those days you could leave your bike without it being stolen so no requirement for ignition switch or fancy security systems!!!

I've been involved with a LOT of 50's bikes, in fact I even used to have a 1952 Velocette Venom on the road, I don't recall any using alternators and magnetos - but perhaps a few did?.

What model Royal Enfield is it?.

My first road bike was a 1964 250cc Royal Enfield, with a Villiers 4T twin engine, next was the 350cc Velocette.

As you say, my Velocette had no ignition switch, just turn the petrol tap (no choke either), kick and go.

The Enfield was alternator and coil, the Velocette dynamo and magneto.

But we had lot's of 50's bikes in the field, and even built them up - Norton, BSA, Triumph, Matchless, AJS, Francis Barnet, James, Greaves - loads and loads of them - good days!

 

[tylernt]

What solution did you end up with?

Nothing. The bike didn't come with a regulator from the factory, so I figured why bother.

 

[2wheelsenough]

Hi Nigel
You bring back some memories with the Velocettes and your list of great British bikes. We had some brilliant engineers that produced bikes making Britain a world leader in motorcycles.
Of the many bikes I have owned over the years, the ones I remember with magneto and alternator are the AJS 650, later and some 500’s, also Matchless 650’s along with Royal Enfield. There are probable more I can’t remember. As with so many companies competing over a reducing market, production cost was very important and magnetos were more reliable than coil n points, giving you an engine that would start with a flat battery or without any battery at all. Also alternators were more reliable than dynamos.
I’m down to 5 bikes at present; the one with 6volt electrics, magneto and alternator is a Royal Enfield 350, starts first kick, very original and still a delight to ride. Whenever I return to it parked up there is always a crowd around it!!! You can buy a newer version of it today, produced I India but with 12volt electrics, electronic coil ignition and probable other upgrades but the frame, suspension and engine are basically as the original Royal Enfield Bullet designed by British engineers. As it says on the petrol tank “build like a gun” (RE’s motto).

 

[2wheelsenough]

Hi tylernt
All this response and you ended up doing nothing!!!

 

[Nigel Goodwin]

Hi Nigel
You bring back some memories with the Velocettes and your list of great British bikes. We had some brilliant engineers that produced bikes making Britain a world leader in motorcycles.
Of the many bikes I have owned over the years, the ones I remember with magneto and alternator are the AJS 650, later and some 500’s, also Matchless 650’s along with Royal Enfield.

As far as I can remember the Matchless/AJS 350/500 singles, had dynamos - we did have one Matchless 650 twin, which was more modern (but still 50's) - but I can't remember it very well.

The singles we did loads of work on, including putting the piston, barrel and head from a 500 on a 350 bottom end.

There are probable more I can’t remember. As with so many companies competing over a reducing market, production cost was very important and magnetos were more reliable than coil n points, giving you an engine that would start with a flat battery or without any battery at all. Also alternators were more reliable than dynamos.
I’m down to 5 bikes at present; the one with 6volt electrics, magneto and alternator is a Royal Enfield 350, starts first kick, very original and still a delight to ride. Whenever I return to it parked up there is always a crowd around it!!! You can buy a newer version of it today, produced I India but with 12volt electrics, electronic coil ignition and probable other upgrades but the frame, suspension and engine are basically as the original Royal Enfield Bullet designed by British engineers. As it says on the petrol tank “build like a gun” (RE’s motto).

Yes, the Bullet was made in India for the Indian Police - who needed a reliable bike, easy to maintain, that didn't need running in. It's amusing that they now export them back to the UK

We never had a Bullet - although a small dealer ('Piggy' Smith) we knew (and bought spares from), had one brand new sat in his shop - never been registered, with the fairing rusting away. He also had a Vincent Black Shadow, and I saw many people try to buy it off him over the years. My first two road bikes came from him.

'Piggy' was a strange old guy, he looked like a tramp, and his shop/yard looked about the same

But apparently he was very wealthy, owned lot's of property, including riding stables - and only ran his shop for the fun of it. If you wanted a part you had to be prepared for a long session, the longer you spent talking to him, the lower the price got

He died a good few years back now, I always wondered what happened to all the 'treasure' in his shop.

 

[2wheelsenough]

Hi Nigel
I do like your story of 'Piggy' Smith.
I think there are some 'Piggy' Smith types still hoarding bikes that sit in the lounge and never turn a wheel, so sad!!!