Forum

[gingerdave]

I have Super Meteor with an unknown past (used as a display bike), I have replaced the wiring loom and have wired it to 6v negative earth as I had already ordered a negative earth EI unit, everything works and the ammeter goes to minus when the lights are on.
Can anyone advise me if I have to flash/repolarise the Lucas RM 13 alternator/stator, I have read a lot of web info on positive to negative conversion, I don't know if I need to do this but I do not want to risk frying the new EI, all articles say flash the field terminal, do I flash the wires if so which one/ones, I have three output wires L/G= common D/G= low voltage(2 coils)Y/G= high voltage(4coils) and a solid state rectifier wired up negative earth, help please.

[gingerdave]

I will check my title spelling next time.

[simon]

The alternator is producing alternating current so won't need any treatment. The only reason for a positive earth that I can glean is because the old plate rectifier puts positive to earth if you modify the rectifier so that it is isolated from the frame and the negative side goes to earth your problems should be solved. Alternative replace the old plate rectifier and all the hideous switched coils on the stator to a modern regulator/rectifier which you can get is 6V form from our hosts or from Pazon if they can't supply. What though if you'll pardon my ignorance is an EI unit?

[simon]

oh reading again seems you already have a modern reg/rec so simply reduce the three wire output from the stator to two for maximum output combining two of the wires together so that you get around 30 plus volts.

[gingerdave]

Thanks Simon, I have restored Japanese and Italian bikes before but the Super Meteor is my first British bike and lessons are coming thick and fast, especially the numerous nut and bolt sizes.
Ps EI unit is my lazy way of saying electronic ignition.

[Dennis C]

OK guys let's just be careful here, I assume you have used the correct wiring diagram for the bike which switches the alternator coils via the light switch, it sounds to me that you are getting your alternator rectifier confused with a dynamo regulator, for 6v from the alternator no regulator is used you only need a rectifier connected in the correct polarity the regulation is carried out by the light switch connecting the alternator winding's to vary the output depending if you have no light's on, side light's on r head light on, commoning the three alternator wire's will make it give out 12v continually.

[Dennis C]

Sorry just read you later post, simple answer, no you don't flash an alternator its a dynamo you flash.

[PeteF]

Alternator doesn't care if you have - or + earth. It's just how you wire it from then on (and you can do it either way) but - earth always makes sense to me.
I have a Tiger Cub wired - earth and recently fitted a modern rec/reg as the old regulating diode had given up. I just followed the - earth scheme (so the rec/reg was wired backwards if you like)
No problems.

[simon]

The switch coil design was a pig of a thing because it almost goes back to the third brush era in that you have two levels of charge regardless of the requirement. This means you are alway boiling the battery. The zener diode of later years fixed this but only for 12 volt systems. A modern solid state 6v reg/rec is a very low intervention mod easily reversed for a purist restoration but that will give you long battery life and less acid splash. It also shows how a 6v system works perfectly well. Not that easy to find but they available and a complete fix.

[simon]

To be frank the charging system is a definitely substandard design for that era but the points and coil ignition is a remarkably trouble free and easily maintained bit of kit. I find it interesting that so many seem hell bent on fixing what aint bust with electronic ignition where the worst ignition Ive suffered was early CDI on my old Ducati. True modern computer contolled setups have a full advance curve but so does a bob weight controlled points set and neither of them have a vacuum control unless you are talking fully modern fuel injected machines.