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[Les H]

I agree with Adrian & Dennis that there is no reason to mix the AC direct system with the battery fed DC system...I've checked the wiring diagram and can't find the headlight cct. going to earth anywhere...the AC regulator is just 2x zenner diodes back to back across the feed and clamps the voltage rise to 12V approx. Having said that there isn't one shown doesn't mean that it wouldn't work if the AC supply was earthed on one side....UNLESS there was a short in the wiring on the opposite leg of the two phases....There is a chance that the insulation on the separate AC coils in the alternator are shorting to the alternator laminations of its construction..See later....However an easy test for an earth short on the AC feed is to remove the yellow and amber leads at the alternator connection and the headlight bulb and then test with an Ohmmeter on these two wires, one at a time, with the other test-lead earthed on the frame. As long as you don't get a short to earth indicated on the meter on BOTH legs there shouldn't be a problem....don't forget to switch the dip switch from main to dip and repeat the test...
Now, do the test on the leads that feed FROM the alternator to see if the alternator is free from shorts onto the bikes earth via its chassis...if there is, the most likely point is where the wires emerge and are clamped to the alternator frame ...this would be easy to fix....see what you get.......Les

[Adrian]

This seems to have opened up a right can of worms. I think both Norm and I now agree that you wouldn't want to mix the AC and the DC, but Norm has seen with his own eyes that someone at the factory has been doing precisely that. Hmmm.



Elsewhere Dave was wondering about fitting a Lucas Energy Transfer alternator for running battery-less. I hope I have been able to persuade him not to go there, as a 2MC capacitor will work with his existing alternator and reg/rectifier unit for that sort of use. However, that got me reaching for my old BSA Victor Enduro workshop manual and a check of the Victor wiring digram...



Now if I'm reading these posts correctly most agree that the Bullet's AC lighting should not need earth wires if you have the amber return wire performing the equivalent function. Wiring diagrams and the Snidal Manual back that up. That said, if the same end of the headlight windings were not only connected to the amber return wire but also to ground through the stator's laminated metal core, then fitting earthing wires would give an additional path for the return current, or at least someone at the factory thought that might be a good idea, but forgot to let the outside world know. I understand such things have actually happened in Chennai.



Looking at the wiring diagram for the Lucas ET stator, both the four ignition windings and the two windings used for lighting ARE earthed, but via external wires, NOT through the rotor's laminated core. This was probably easier than running AC return wires, as ALL the lights as well as the ignition were AC, no rectifier anywhere in the circuit.



**SO**, is the return side of the Bullet's AC lighting system on the alternator stator isolated from the laminated core, or is it connected? Well I don't have a 4 wire stator to check but I do have a new 6 wire Machismo/Thunderbird alternator in front of me, wires 5 and 6 are for the CDI charging coil which replaces one of the lighting coils, leaving three coils with heavier gauge wire which I assume are for the AC headlight, and two coils wound in lighter gauge wire which I assume are for the DC side (stop/tail light, indicators, pilot light and horn - ignition is taken care of by the CDI charging coil, this too is independent of the DC electrics).



Looking carefully where each coil has been wound around its plastic bobbin (good job it's not encapsulated), it is possible to see where each end of the copper wire exits the bobbin, and both ends are joined to separate external wires, with NO SIGN WHATSOEVER that any of the five lighting coils have any electrical connection to the laminated core. OK, this is a pattern rather than an OEM item, but if the Sixty-5's alternator stator was assembled the same way, that means that the unadvertised factory procedure of adding earth wires to the amber return wire is COMPLETE AND UTTER NONSENSE. Do not replicate it. Norm, you were never SUPPOSED to get your head around the extra black wires, as it looks like not even everyone at the factory understood the AC lighting!



Mystery solved? When I get around to fitting this beastie to my reconditioned, re-balanced Machismo crankshaft (it's replacing the crank in my *l*ctr*-X with the failed big-end) I won't be joining any black wires to the amber - unless I convert the headlight feed to DC with a common earth!


A.

[Norm]

Dennis I was going to bring up the A/C domestic household wiring, the neutral wire is connected to the earth bar in the back of meter box.

[Dennis C]

Not sure how it works where you are Norm, but in the UK it most certainly does not. And I would be amazed to find that it does anywhere else in the world, that would completely negate any value the earth has. Nope definitely not just checked "AS/NZS 3000 standard, commonly known as the "wiring rules"" and it is pretty much the same as here.

[Norm]

So Dennis how does a light bulb work it requires a circuit

[Norm]

My last comment on it Dennis, why if you touch the active and neutral wires together in a light socket do you get a big bang, because it shorts to earth

[Dennis C]

Norm, a domestic electrical installation has three wires live neutral and earth, all separate the live and neutral form the circuit and the earth is there as a safety feature,I think as I worked my entire life with electricity I perhaps could be correct in saying this. We refer to a bikes electrical return as an earth return because it uses the frame Etc as the return path to save wiring and confusingly it has a different meaning to a domestic earth.

[Les H]

Hi Norm. The Live and Neutral wires in the Domestic Mains AC supply are just the same they carry a single phase (50 or 60 Hz) AC voltage and whatever flows through them is the same alternating current...they are simply different coloured wires... For safety reasons one of them is connected to earth/ground at the fuse box (consumer unit) end...this then becomes the Neutral side....it could easily be the other wire. Obviously then all the wiring is taken away on colour coded cable which you then call LIVE and Neutral but as far as the voltage and current on them they are a single pair and no different. You then have the earth wire connected to the same earth point as the Neutral wire is at the fuse box end....So you can see that if the Live side is accidently connected to the earth via the equipment's metal parts that have been earthed or any wire along the wiring you have effectively short circuited the Live side to the Neutral wire because, as just explained, these two wires are joined together back at the fuse box...this then blows the fuse or trips the earth leak detector....Les

[Les H]

I Know this is going to sound wrong, but with a motorcycle alternator you don't need a fuse because if the output is shorted together the voltage and overall current though the windings self limit. In fact if one studies the old Lucas 3 wire alternators and their switching, there is one system that actually shorts one set of coils together by the lighting switch to limit the output of the other coils, the output is lowered because of the interaction of the flux in the rotor and the flux being generated in the coils windings and reduces the overall output....noting that the alternator coils are set in a radial layout ....will try to find the article to explain....if I have time.....Les

[Dennis C]

I hope I do this correctly if I do then a picture will appear below showing a mains consumer unit has three completely independent circuits, The neutral does not connect to earth, (sorry Les)