1969 BSA A50 POSITIVE OR NEGITIVE EARTH

[bsaa50hotrod]

hi all,im new to this site and already have a question,first, im very familar with many 60s-70s triumphs but not bsa,and as i recall,they were positive earth electrical systems,im in the process now of doing a 1969 bsa royal star a50,my problem is my haynes manual does not indicate(anywhere that i can see)whether this is a positive/negitive,can anyone help out here?thanks

[L.A.B.]

Definitely positive earth originally, although you can wire it negative earth if you wanted to?
But you would need a negative earth Zener and different rectifier, or a modern voltage control box that replaces both of those items which can be connected according to the chosen polarity?
The coil wiring would also need to be reversed for negative earth use, so that the coils (-) terminals were on the earth (points) side.  


PS

The relevant wiring diagram in my Haynes A50/65 manual certainly shows the battery is wired positive earth.   

[dunboyne]

is there any advantage to converting from positive to negitive earth .

[iansoady]

Most electronic ignition systems are negative earth. I prefer it myself as most vehicles these days are negative earth and it helps prevent brain fade......

[bikerbob]

I have a 1963 A65 and it is positive earth it is fitted with Pazon electronic ignition which can be wired up either positive or negative earth.

[Rex]

Other than "EI units you might buy in the future" there is no advantage.

[mini-me]

 my older bike is neg earth
my middle one is pos earth
when I used to muck about with more bikes I went neg earth for 12v.

I do however stay well away from electronic ignition.

Other than that with acetylene lamps its no problem