Alternator Help!

Al Oz is the man to ask.

No Norton ever had a three phase alternator from the factory/standard. The MKIII and the JPN both had a two wire high output stator.

The colours you have are non standard. You can experiment to find the right two to put together, if wrong it will only reduce the out put. But it very will/should be a Wipac especially as the Wipac rotor is an odd size. But there is nothing wrong with the rectifier/zener set up. Although it would be worth checking the Zener voltage (I can do it, might be worth sending me the rectifier as well). There is an original Wipac alternator diagram on my web site aoservices.co.uk and full information for the 12V set up. 

Hello Mike trust you are well.

There must be some maker's identifying marks on the rotor, whether Lucas, Wipac or something else that's been grafted on. Maybe some past owner has fitted something off a jap bike when "upgrading" the electrics?

Michael you seem to have got it wrong-ish. There are two parts to the Lucas-Wipac alternators. The Lucas rotor fits a 19mm (3/4) shaft. The Wipac is 1" so near the twain shall interchange. But the OD of the Wipac allows it to be used with a Lucas stator (which is often done on the lightweights.) The slightly increased gap will reduce the electrical output a little bit.

Then there is the stator, Lucas or Wipac. This is a totally separate item, and can often have its wires replaced (a small services I can do) but a lot of people use mains lead as of course you have 3 wires inside a nice rubber sleeve. But the colours are wrong! Confusion begins here.    But if you can't sort out the colours ie what wire is what then you can guess until you get it right.

There is a Common, a Low output and a High output. Measure the charge voltage (or monitor the ammeter closely). Put the Common to one side of the rectifier, one other wire to the other side, start engine, monitor charge. Use other wire, note charge. IF you have found the right two wires to put together then doing that will increase the charge to its best. If you have it wrong try again.

Yes but, most people cannot use a multi-meter properly to do that. I have also just helped a trade chappie with the same issue, he found that putting Low with High-reduced the output!! Eventually he returned the Sparks stator as faulty, which was agreed by Sparks. So ohms measurement might get a result but a) hard to do b) not as conclusive as putting the wires together. By the way the Navi and Jubilee have 50/50 alternators so High and Low is not relevant BUT putting the wires together will satisfy the above ruling.

The original wire colours were Orange, Green & White, and the alternator was designed to run a 6v system, by connecting 3 coils between white & orange, and the other 3 between white and green. There was also a resistance wire in the loom to soak up excess charge. This is how it worked normally (when it left the factory).

1) No lights, IGN on - 3 coils were in circuit to charge the battery, excess current passing down the rersistance wire.

2) Sidelight, speedo & tailight on, IGN on - same as above, but resistance wire not connected.

3) Headlight on, IGN on - 6 coils now in circuit, powering the lights and still maintaining a charge.

4) Flat Battery condition. No lights, EMG ignion on - 6 coils in circuit, maximum charge rate.

Sixty years later....does any of it still work? Did Al tell you above how to test the alternator? You need a 20Volt meter & a very sensitive ohmmeter - one that can measure 1Ω or less.

Between orange & white, expect around 0.5Ω - 0.7Ω - same between green and white.

Between green and orange expect double the reading you got above. About 1Ω - 1.5Ω

For 12volt operation, join green & orange together to form one wire, and use the white as the second wire - both then go to your regulator/rectifier AC input. (sometimes coloured as two pinks, or two yellows).

You do not need a Zenor diode if using a regulator/rectifier.

PS - your alternator is not 3-phase.

PPS - I mentioned a Resistance Wire above - that is used only on 6v. If using 12v, that wire (& others - speak to Al Oz) needs to be disconnected.

PPPS - Another vital test is to see there is no path to earth (Chassis) from any (does not matter which) of the 3 wires. For this you need a high Ohms range - 100MΩ or higher. Generally, you are on the right range if you can read your own skin resistivity.

Ideally you should see no reading. In practice however, you may detect a slight reading - but it needs to be higher than 500KΩ or more.