6v to 12v conversion question

[johnny650]

I finally got around to converting a 6v lambretta Stator to12v by replacing the 4x lighting coils from a Vespa PX stator. No problems that far .

However there seems to be two different wiring methods recommended for the lighting coils with some conflicting information and little or no explanation of which is the better solution.

One recommendation is to wire all the 4x lighting coils IN SERIES like the original Vespa stator ,with one end earthed and the other end to a 12v regulator feeding 12v AC power all of the lights and horn from a single wire .This would naturally require a bit rewiring to the loom , headlamp, switches lights etc but should give super powerful lighting.

The second option (ScootRS) is to wire two pairs of Vespa coils IN PARALLEL to feed the 12v regulator ?

What is the advantage or disadvantage of the two wiring options ?
1. Four coils in series or
2. 2x pairs of 2x coils in series connected in parallel

[johnny650]

Ahhh ...I see... said the blind man, picking up his hammer and saw.

I just found a wiring diagram in the back of Sticky pg 227 called ' The MB-type simplified wiring loom for 12v electronic ignition conversions '

it shows all the lighting coils in series , with one wire connection to a 12v AC regulator so presumably MB is where this wiring option originated from.

There is no reason however why one couldn't use a points & condensor stator rather than a electronic stator .

I presume that the split wiring suggestion in scootRS diagram is to split the lighting supply so that operating the brake light doesn't dim the head and tail lights which is presumably what happens to the lighting coils when wired in series (MB )

[Adam_Winstone]

Not sure. I've been running a 4 in series version of modified points OEM Ducati 6V to 12V for a number of years on one machine and that has been a very good upgrade. The lights are no different than you would find on a 12V electronic kit and the ignition is as per Innocenti's original points systems, with it being nice to have retained the original flywheel and coil.

I don't know what the benefit of 2 x 2 might be but I'll keep my eye on this developing thread.

Adam

[mick1]

I may be wrong, but ......

If all 4 are wired in series then each one must produce 3 volts to give 12 volts.

By linking 2 in parallel with the other 2 this would only produce 6 volts .

Looks like a bit of confusion somewhere, unless you want to stay at 6 volts.

[Chris in Margate]

+1 to that

[johnny650]

sorry chaps I've not been receiving my email notifications again for some reason .

Thanks for all your replies ..much appreciated.

@ Adam ..thats a good positive feedback Adam thanks. The only issue that I have read about is a possible dimming of the lights when applying the rear brake . Apparently the way round that is to fit an LED brake light bulb which seems to be a good mod anyway .

@ Mick ... yes it does seem confusing to have two different recommendations doesn't it ..Thats why I posted on here hoping some bright spark (geddit?) has the answer for us.

Don't forget that the combined output of all four lighting coils is regulated at a stable 12v AC so there shouldn't be any significant drop off in lamp brightness with lower revs . That is afterall one of the main reasons for doing this conversion.
Someone needs to do a AC voltage test and produce a nice graph for us

@ Chris ..... I was relying on you to have the answer .....you would have thought that by now someone would have written an explanation about this conversion wouldn't you. I'll have a looksee over on MB's site there may be something there .
Because this has been largely superceeded by electronic ignition a lot of sites have removed there information about this conversion.

[Adam_Winstone]

Funnily enough, I have an LED rear bulb fitted. However, this is no different to many of us running the common electronic kits... 100% same lighting scenario when the 4 lighting coils and regulator are fitted.