Author Topic: '61 BSA neg or positive earth?  (Read 3399 times)

Offline Elyvas

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'61 BSA neg or positive earth?
« on: April 01, 2009, 10:20:14 PM »
Please can anyone help? I have a 1961 BSA Golden Flash which has a 6v battery for headlight and horn, at present it is negative earth but the battery is draining very quickly (over night) and isn't charging and the amp meter goes way up as soon as the battery is connected. Yes, it is my 2nd new battery. If I disconnect the Earth wire the battery doesn't drain?  I know nothing about bike electrics but a chap who knows tractor electrics suggested maybe the bike should be positive Earth? Any advise gratefully received. Thanks.

Offline L.A.B.

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Re: '61 BSA neg or positive earth?
« Reply #1 on: April 01, 2009, 10:36:17 PM »
Your Golden Flash would have been positive earth originally.

Presumably it was converted to negative earth at some point in the past, as many owners are more familiar with neg. earth systems these days.
So just reversing the battery polarity probably won't cure the problem if there is a fault elsewhere, such as a failing rectifier (or does it have a dynamo?) or a partial short somewhere that could also be causing the battery to drain quickly but not blow the fuse (it is fitted with a fuse, isn't it)?

If your Flash has a dynamo, (instead of an alternator & rectifier) then the regulator could be faulty?
« Last Edit: April 01, 2009, 10:54:14 PM by L.A.B. »
L.A.B.

Offline chris perfect

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Re: '61 BSA neg or positive earth?
« Reply #2 on: April 02, 2009, 12:27:58 AM »
If It has the original rectifier or old fashioned one change it to a solid state version. It could be as simple as that and costs peanuts.
Is it blowing fuses ?
« Last Edit: April 02, 2009, 12:32:39 AM by chris_perfect »