BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JRC Engineering dealers
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
DPO
DPO
Douglasville (Atlanta) Georgia
Posts: 1,649
Joined: June 2007
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
27 registered members (blackrag), 182 guests, and 364 spiders.
Key: Admin, Global Mod, Mod
Newest Members
IDG1, pemdoc65, creativecroc, gregneal, Chris Marsland
10170 Registered Users
Top Posters(30 Days)
Lannis 97
Stuart 83
reverb 80
NickL 71
koan58 56
Popular Topics(Views)
549,851 mail-order LSR
Forum Statistics
Forums34
Topics66,550
Posts645,144
Members10,170
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
+ to earth? #15086
09/06/06 8:16 pm
09/06/06 8:16 pm
Joined: Jan 2006
Posts: 149
Oslo
R
Rocker Offline OP
BritBike Forum member
Rocker  Offline OP
BritBike Forum member
R
Joined: Jan 2006
Posts: 149
Oslo
My newly purchased 1940 M21 did not have light`s, until today. When I had a look in the battery case I found a wire that had come loose. I fixed it and after a little while I had lights !!

But one thing I don`tunderstand is that the bike had - to earth, not + to earth like I`m used. Is the battery faultly connected and if so, is it still possible that the lights could shine bright ?

Or should M21 have negative earth like mine might have?


1940 M21
1960 Golden Flash

"Everything takes longer time than it takes"
Support your #1 BSA Forum and our favorite sponsors

Check out BSA on e-bay: BSA Parts in UK, BSA Motorcycles in UK, BSA Parts in North America, BSA Motorcycles in North America

 
 
Re: + to earth? #15087
09/06/06 8:37 pm
09/06/06 8:37 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
BritBike Forum member
beezageezauk  Offline
BritBike Forum member
Joined: Apr 2002
Posts: 962
North East England
BSA Service Sheet number 808 shows the wiring diagram for the A,B & M group models. My copy has the date October 1948 and it is for a negative (-)earth system. These machines changed to a positive (+)earth system some time after 1948. I am sure that somebody can tell us the date of the changeover.

As your bike is a 1940 model, the negative earth system is correct.

Beezageezauk.

Re: + to earth? #15088
09/07/06 12:22 pm
09/07/06 12:22 pm
Joined: Aug 2006
Posts: 33
Alexandria, Virginia; U.S.A.
Mark Taylor Offline
BritBike Forum member
Mark Taylor  Offline
BritBike Forum member
Joined: Aug 2006
Posts: 33
Alexandria, Virginia; U.S.A.
Interesting... my recently purchased 1965 A50 also had the (-) side of the battery to ground. All of the literature I have suggests that it should be (+) to earth (BTW, it is a 6V battery). Question: if one of the previous owners got it backwards, what problems may I be facing?


Mark

2004 Triumph Daytona
1965 BSA
Pre-unit Triton
Re: + to earth? #15089
09/07/06 7:13 pm
09/07/06 7:13 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
BritBike Forum member
beezageezauk  Offline
BritBike Forum member
Joined: Apr 2002
Posts: 962
North East England
The BSA Twin Restoration book states that BSA started using positive earth systems in 1951. I take this to mean for all models and not just on the twin cylinder machines.
It doesn't state in it that BSA reverted back to the negative earth system. However, it does mention that the the 12volt system was standardised on the twin cylinder models in 1966. On saying this, some machines had 12volt systems prior to 1966, but not all of them.
Your A50 is probably correct with a 6volt system but it appears that it should have a positive earth.
Do we have any electrically orientated guys here who can advise and maybe comment on my findings?
Beezageezauk.

Re: + to earth? #15090
09/07/06 7:39 pm
09/07/06 7:39 pm
Joined: Sep 2001
Posts: 296
Winston, Oregon
B
beezerbill Offline
BritBike Forum
beezerbill  Offline
BritBike Forum
B
Joined: Sep 2001
Posts: 296
Winston, Oregon
One thing to remember BSA has a pos grd for some kind of safey thing a million years ago..anyway if your battery is completely dead it is very possible to charge it up backwards so what you end up with from the battery < is a negitive which is the postive..and a pos. which is neg.I just know this is got to helpful..Beezerbill

Re: + to earth? #15091
09/07/06 8:40 pm
09/07/06 8:40 pm
Joined: Aug 2006
Posts: 33
Alexandria, Virginia; U.S.A.
Mark Taylor Offline
BritBike Forum member
Mark Taylor  Offline
BritBike Forum member
Joined: Aug 2006
Posts: 33
Alexandria, Virginia; U.S.A.
beezageezauk, I agree. Everything I've read suggests that a 1965 A50 should be a 6V system with a positive earth.

beezerbill, I've heard the same thing... if the battery is completely dead, it's possible that the alternator could reverse the battery's polarity.

I think I'll see if the battery will hold a charge and then re-install it with a positive ground and see what happens... tahnks for your help!


Mark

2004 Triumph Daytona
1965 BSA
Pre-unit Triton

Moderated by  Allan Gill, Jon W. Whitley 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.1.1
(Release build 20180111)
Page Time: 0.077s Queries: 14 (0.005s) Memory: 1.0198 MB (Peak: 1.1713 MB) Zlib disabled. Server Time: 2018-04-21 04:03:07 UTC