1962 Dommie wiring dilemma

If it's 12 volts, you should find a zener diode or a solid statevoltage control box wired in there somewhere. Also, the 3 wire alternator should be wired to suit, i.e. it wouldn't have the third wire disappearing up to the light switch.

I would suggest you go for a 12 volt system providing better lighting which is becoming essential in these days of every car having permanent headlights. It's amazing how drivers don't notice anything which doesn't have a searchlight blazing at them.

Hi Peter, It sounds like you intend to carry on with the distributor and PRS8 for orriginality. No problem with that, but I would fit a modern combined rectifier/regulator or add a zener and heatsink to your existing 12v? rectifier. The PSR8 current switching facility can be made redundant so the wiring can be simplified.You will need a 12v coil( check the diameter to fit your bracket) ,the orriginal? 6v hooter may survive 12v (mine has) but its not good practise.The distributor capacitor may also work but can be replaced with an external car one . You should consider fitting some fuses.IF you have an efficient alternator you may find the zener hard pressed to dissapate any unwanted current,but as I have indicators and tend to ride with side lights on its not a problem. My old low output alternator is still fine. I have also added a 2MC capacitor to the system to allow flat battery starting .I was not impressed with the light weight new looms( may be better now?) and just replaced bad stuff. Fit a good earth wire up to the headlight.Some wiring diagrams have an error with a link wire on the PSR8 ,can't remember what I did!.

You could stick with the orriginal layout and just bundle the alternator output , This does however give the battery a hard life .

12V would be the way to go. Zener diodes are good to use but the present supply is of chinese decendancey and of limitations in its power handling, although with the original alternator you won't have too much power anyway. I do a wiring kit that might be of use to you and a 12V regulator/rectifier. The PRS8 switch will be ok on 12V as well. Otherwise all above from RT is in good order. A O Services.co.uk

Al O

Been reading this thread with interest. I'm getting to know my 1959 99 which is running 6v on three wire unencapsulated alternator and a selenium rectifier. Today did 25m with a 6v ATM 7ah battery fully charged fitted.

The ammeter showed some inconsistent discharge/charging going on when lights on and off. I'm thinking of trying a DVD2 regulator set at 6v but is this going to have knock on effects for the selenium rectifier?

Or should I chuck it all in and go for 12v,Chinese reg/rec, New batt,coil,bulbs etc?

Not likely to do much night riding but would like decent day riding lights.

Hi Barry, without knowing what switch you have its hard to sus the problem. Its possible that you have a PRS8 which does give different ampmeter readings dependent on light selection,also if you have a bad connection /alt problem you may find the charge ok on pilot but dissapears on main. Describe the problem, some ampmeters dance all over the place anyway. If you have a voltage control and a fully charged battery you will see some odd readings too. The strangest readings I've ever seen was when I went for a ride on my coil ign bike and forgot to re-fit the battery!!.

Hi Peter,how did you get on with your 12v conversion?.Not sure that we answered your questions fully. The system will supply 6 or 12 v depending on what you fit, It is possible to have 6v ignition and 12v everything else if a ballast resistor is used,but its better to change the coil to 12v. Although the PSR8 looks orriginal its a bit of a beast ,not really waterproof, can fall appart, strip threads, and some of its functions become redundant in the conversion. A good orriginal is worth keeping but modern pattern replacements have a poor rep. A simpler switch may be more reliable.

Previously robert_tuck wrote:

its possible that you have a PRS8 which does give different ampmeter readings dependent on light selection,also if you have a bad connection /alt problem you may find the charge ok on pilot but dissapears on main. Describe the problem, some ampmeters dance all over the place anyway.

Thanks Robert, yes it is a PRS8 and its original. I've taken it apart and cleaned the contacts as best I can, it seems very good except the thread on the bakelite post bit that pokes through the headlamp bowl has worn thin.

The symptoms are very similar to the way you have described them;

- with no lights; ammeter is charging very strongly although it will drop back to midpoint at lower revs.

- with pilot light; ammeter hovers around middle but will go well into charging territory

- with headlight on; well into discharge even at high revs (55 mph on clock) it only approaches midpoint and never gets there.

Sorry can't give actual amp readings as there is no marked scale on the ammeter.

As you identified it could be bad connections, I do need to check out the state of the wiring, it's on the list. I'm assuming a DVR2 regulator would work as the current will be rectified to DC, I've got one on two of my other bikes but they are 6v dynamos on DC.

Running with coil ignition and selenium rectifier as factory set up. Long term plan to convert to magneto.

Previously Barry Robinson wrote:

Been reading this thread with interest. I'm getting to know my 1959 99 which is running 6v on three wire unencapsulated alternator and a selenium rectifier. Today did 25m with a 6v ATM 7ah battery fully charged fitted.

The ammeter showed some inconsistent discharge/charging going on when lights on and off. I'm thinking of trying a DVD2 regulator set at 6v but is this going to have knock on effects for the selenium rectifier?

Or should I chuck it all in and go for 12v,Chinese reg/rec, New batt,coil,bulbs etc?

Not likely to do much night riding but would like decent day riding lights.

I think we must get a few of our facts straight-a DVR2 is a DYNAMO regulator yet we are talking about alternators.

I doubt very much if you have a SELENIUM rectifier, they are either 3" diameter or maybe 2 1/2" in grey or green. Throw them away! If you have metal plates about 1 1/4" diameter painted Black these are the very common Lucas item (or replica of) and are SILICON. IF they are in good order, ie unbent, no loose centre bolt etc they are are fine to use. They can be replaced by the modern encapsulated 1 1/4" alloy square one which is virtually bomb proof, 4 sticky up terminals so you have to make an earth connection. (the original items use the centre bolt as earth.

There is nothing wrong with the original Lucas Zener as regulator for 12V. Or the new style regulator/rectifier

AO

Sounds like you have a dud coil or conection and are not getting the full alternator output. Could also be a corroded switch connection.

It seems that I may have a problem similar to Peters original post. I have literally just taken ownership of a 1960 '99'. Looking at the wiring and the switch mounted on the headlight it looks as if some 'less than talented genius' in the bikes past has done a 12v conversion andrewire and have used just about the full spectrum of cable colours. They have alsoreplaced the original PRS8 ignition/light switch with a three position switch,put a 'kill' button on the handle bars along with a two way switch with a push button that I assume is something to do with the lights and horn, (unless of course it's the ignition switch as the is no obvious signof an on/off switch anywhere else),I'm currently waiting for a new battery and once that's charged and installed I'll start with a wiring diagram and multi-meter to try to sort out the less than perfect'wiring'. A first assessment would suggest the easiest way to sort out the mess will be to geta replacement Lucaswiring loom and PRS8.Any comments /advice will be welcome as I'm a Norton 'newbie'.

Hi John...you said above: " A first assessment would suggest the easiest way to sort out the mess will be to geta replacement Lucaswiring loom and PRS8"

That is exactly what you should do...the loom will cost about 50 quid... not sure of the price of the switch . It will be quicker and better in so many ways, in fact if your wiring is that mutilated it would be insane to try to sort it out. You will get the benefit and reliability for the the rest of your ownership of the bike....it will be an investment.

Les

PS....I would say there are probably good and not so good wiring harness looms on the market, perhaps someone here could recommend one to you...?

I bought a new harness for my 99 about 20 years ago( from a Norton specialist) , decided it was far too flimsy and threw it into a corner( its still there). I ran a new earth wire up to the headlight and re-used the 1960 loom with alterations to suit 12v ,a fuse,a zener,a 2MC, indicators and extra lights on panniers , I suspect it would be difficult to follow now with the colours not correct. The PSR8 switch can be stuck in the shell with silicon (YUCK!) if the thread is weak but only after its all been tested and working well. Anyone who has the patience and ability to rebuild a PSR8 needs no advice at all!.

Previously les_howard wrote:

Hi John...you said above: " A first assessment would suggest the easiest way to sort out the mess will be to geta replacement Lucaswiring loom and PRS8"

That is exactly what you should do...the loom will cost about 50 quid... not sure of the price of the switch . It will be quicker and better in so many ways, in fact if your wiring is that mutilated it would be insane to try to sort it out. You will get the benefit and reliability for the the rest of your ownership of the bike....it will be an investment.

Les

PS....I would say there are probably good and not so good wiring harness looms on the market, perhaps someone here could recommend one to you...?

Thanks for the advice Les. I think RGM at Beckermet do a main wiringloom for about £45 and PRS8 for £70 and the best bit is that they are only about 5 miles away from me so I think a phone call to them is in order.

John

Previously John Sunderland wrote:

Previously les_howard wrote:

Hi John...you said above: " A first assessment would suggest the easiest way to sort out the mess will be to geta replacement Lucaswiring loom and PRS8"

That is exactly what you should do...the loom will cost about 50 quid... not sure of the price of the switch . It will be quicker and better in so many ways, in fact if your wiring is that mutilated it would be insane to try to sort it out. You will get the benefit and reliability for the the rest of your ownership of the bike....it will be an investment.

Les

PS....I would say there are probably good and not so good wiring harness looms on the market, perhaps someone here could recommend one to you...?

Thanks for the advice Les. I think RGM at Beckermet do a main wiringloom for about £45 and PRS8 for £70 and the best bit is that they are only about 5 miles away from me so I think a phone call to them is in order.

John

If RGM is just down the road then that could be a good way to go BUT I can offer another way, I supply a wiring kit for any Alternator (or dynamo) bike. This includes the colours from 1963 which might not be in your Norton manual but was the industry standard at the time and right through the industry for very many years.Yes I am in the trade but I have always felt that a fresh rewire with wires and connectors beats a standard loom, as by the time you have sorted the loom, found the mistakes added your changes 12V etc then you might have just wired it and stopped fiddling with an indifferent loom.AL O

Previously alan_osborn wrote:

Previously John Sunderland wrote:

Previously les_howard wrote:

Hi John...you said above: " A first assessment would suggest the easiest way to sort out the mess will be to geta replacement Lucaswiring loom and PRS8"

That is exactly what you should do...the loom will cost about 50 quid... not sure of the price of the switch . It will be quicker and better in so many ways, in fact if your wiring is that mutilated it would be insane to try to sort it out. You will get the benefit and reliability for the the rest of your ownership of the bike....it will be an investment.

Les

PS....I would say there are probably good and not so good wiring harness looms on the market, perhaps someone here could recommend one to you...?

Thanks for the advice Les. I think RGM at Beckermet do a main wiringloom for about £45 and PRS8 for £70 and the best bit is that they are only about 5 miles away from me so I think a phone call to them is in order.

John

If RGM is just down the road then that could be a good way to go BUT I can offer another way, I supply a wiring kit for any Alternator (or dynamo) bike. This includes the colours from 1963 which might not be in your Norton manual but was the industry standard at the time and right through the industry for very many years. Yes I am in the trade but I have always felt that a fresh rewire with wires and connectors beats a standard loom, as by the time you have sorted the loom, found the mistakes added your changes 12V etc then you might have just wired it and stopped fiddling with an indifferent loom. AL O

After spending most of this afternoon in the garage with the Haynes and a multi-meter it seems the chap who 'rewired' my Dominie has made it into a 'hybrid'. Some of the wiring actually matches parts of the diagram for a 650SS. Now that the battery is in I was able to trace the wires from theheadlight switch to the horn/dip switch which needs replacing anyway. All the lights except the stop lightare working along with the horn.

Al O. I'll have a look at your website andmight very well be in touch regarding your kit. I can always 'edit' the existing wiring diagram to match the rewire and keep it in the file.

This probably doesn't help but most 'modern' replacement 6 Volt batteries are under-powered compared with the old Lucas type PUZ7E/11 - which is listed as 12 amp-hour at the 10 hour rate. (14 amp-hours at the 20 hour rate) This compares with apparently common ratings of only 7 amp-hours for modern batteries. Very little reserve there.