The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: DartmoorStar on 18.06. 2019 16:28

Title: Can anyone identify?
Post by: DartmoorStar on 18.06. 2019 16:28
Hi - The Bike an A7 SS 1961 has stood garaged now for over 20 years, I bought a new replacement battery (6 volt system)- which had been disconnected - now i have assumed ( and  I know that can bite you on the A**) that the two ringed connecters on Red and Blue wires in Pic are Blue (-ve) and Red (+ve) Battery connections , however there are two taped together Brown Wires left that I am unsure what they are - can anyone help from the picture i have attached  or if more info is required I will try my best to supply. Not sure when my father wired it what way it was done or if correct colour coding was utilised. Pointers welcome to get this one up and running again. Thanks in advance.
Title: Re: Can anyone identify?
Post by: Bsareg on 18.06. 2019 18:02
Without starting the bike, what's not working ? There should be nothing on the bike that could be damaged through wrong polarity, so first see is working. 
Title: Re: Can anyone identify?
Post by: duTch on 18.06. 2019 20:28

 Is difficult to see where the brown wires go- you should be able to find the other ends relatively easy....maybe the horn or brake switch.??

 Unless you have some kind of 'lectronic ignition, the bike can be started without a battery with just magneto sparks
Title: Re: Can anyone identify?
Post by: morris on 18.06. 2019 20:49
There should be a brown wire coming from the ammeter that connects to the battery negative. The other connection on the ammeter should be brown/white and coming from the regulator. Another brown wire from the battery negative connects to the horn and the stop light switch. This might explain both brown wires (ammeter/horn) twisted together. The battery positive side connects to the frame but should be black. Check that your red wire connects to the frame and nothing else  (all assuming your bike is wired as standard, which  is positive to the frame)
No idea where the blue wire is coming from as a blue wire is definitely not standard in the loom.
Title: Re: Can anyone identify?
Post by: RogerSB on 18.06. 2019 22:44
I agree with Morris. On my 1960 swing-arm two brown wires are fed via a connector from the live (negative) terminal wire on battery, one goes to + on ammeter and from there to horn. The other to stop light switch and then on to the rear light.

Two brown and white on the ammeter -, one to A on a dvr2 or to control box if you have one still fitted, the other goes to the lighting switch (in my case to terminal no 3).
Title: Re: Can anyone identify?
Post by: DartmoorStar on 19.06. 2019 00:10
Thanks for your replies all helpful, is there access to any wiring Diagrams to help me trace the loom, i'm sure it is a custom reworking of my Father's doing so not correct colouring as you suggest.
Title: Re: Can anyone identify?
Post by: scotty on 19.06. 2019 06:38
Howdy Mr Dartmoor Star

There are links to the factory service bulletins on the forum that will include wiring diagrams.

I purchased a loom from a supplier who provided me with this diagram

Ignore my scribble on the bottom right

Title: Re: Can anyone identify?
Post by: Swarfcut on 19.06. 2019 09:30
The non earthed lead on the battery goes to one side of the ammeter. If connected correctly, without the engine running you should get lights and a discharge on the ammeter.  Horn is usually fed from this ammeter terminal, so does not show a discharge. Brake light is fed directly from the battery. So in summary, if the horn and brake light don't work, joining these wires to the battery will give power to these items. If you have horn and brake light, just make a reliable  connection of these wires. With the engine running, assuming standard magneto ignition, the lights will work without the battery connected.

 Good idea to put an in line fuse in the battery earth lead. 10 amp is a good starting choice.

 Just read your earlier posts. Before attempting to start 'er up, there are a few critical items to check and procedures to observe, so have a good look around the Forum at what's what before you get jumping on the kicker. Have a look for Barnfind Bikes.

Title: Re: Can anyone identify?
Post by: RogerSB on 19.06. 2019 09:58
DartmoorStar, thanks for the message.

Here's my wiring diagram (for my own 1960 G/Flash).  When I bought my bike the electrics worked, except the dynamo wasn't charging the battery, and the wiring was in a terrible mess with bad connections, different coloured wires cobbled together to make up one continuous length, etc, etc. and so I had to sort it out myself. I couldn't get some of the original two-colour wiring so I had to make due with what was available - so some colours are not as original.  This is why I drew up my own diagram (see .pdf), to represents my own particular bike and to make it easy for me to trace any wiring problems in the future, but it is very representative to the original wiring layout.

No doubt there are some who will say my G/Flash is about to explode or go up in flames  *sarcastic*
Title: Re: Can anyone identify?
Post by: Swarfcut on 19.06. 2019 10:33
Roger.. On the contrary. That is one of the best layouts, nice a clear, not about to flare up thanks to the fuse in the feed line. The fuse in the earth is ineffective as it is wired in parallel with a big hefty lead to the rear light fitting which is electrically connected to the mudguard and frame.
 I suggested  a10 amp fuse, I suppose 15amp is more suitable with high output systems and big wattage bulbs.

 The Draganfly schematic of the loom from Scotty was fine to tell what goes where, but your scheme shows how it all works. The system is more or less the same over the years, only the wiring colours, polarity and individual types of component changed.

Title: Re: Can anyone identify?
Post by: RogerSB on 19.06. 2019 11:33
Thanks Swarfy.  I must admit the earth from rear light to the battery + earth is a very recent addition (actually only 2 days ago).  Over the past few weeks my bike has been up on it's work platform for a fork overhaul, a new rear sprocket and while waiting for replacement parts I took the outer and inner covers off the gearbox to check if anything was amiss after detecting a slight difference in sound in certain circumstances. Pleased to say (to me) all looked fine but while it was out I did renew the mainshaft bearing and bushes in the inner cover. During this time I also stripped and resprayed the fork legs, trousers, front mudguard & its fittings. Then the rear mudguard and number plate, finishing it all this weekend, only to find the rear light and the stop light wasn't working.  Bearing in mind that, in addition to the rear light, all the wiring inside the nacelle had also been disconnected. I was sure I had connected it correctly but removed the headlight to check. All was ok and I was puzzled.  I eventually traced it to the rear light not having an earth, so I added the new earth wire and all worked fine. Previously the earth must have relied on a bolt from the light fitting making earth through the mudguard and, of course, I would have painted over it. Checking an original wiring diagram for my bike's year there was no separate earth wire from the rear light and it must have relied, from day one, on making an earth through the tinware, frame and to battery.

Now waiting for my son to come and help me take it off the work platform.
Title: Re: Can anyone identify?
Post by: Swarfcut on 19.06. 2019 13:39
Roger, just route your new earth return via the fuse to the battery, rather than straight to the battery. An earth added from the headlight to the battery, again via the fuse will eliminate poor connection due to the grease and muck on the steering head bearings, as the standard set up uses the bearings as an earth path to the frame.

  A good excuse to go out and about is down to Sutton Harbour for a nice new stainless shackle....the hoist you have will eventually cut through that piece of quality string....been there, done it.

Title: Re: Can anyone identify?
Post by: RogerSB on 19.06. 2019 14:04
Hi Swarfy,

Yes, thanks, good point, I'll put it to the earth bolt under the seat rubber bump stop. The main earth wire goes from that bolt through the fuse to the battery.

I forgot to mention this earlier but my original reason for the fuse on the earth side, in addition to the live side, was so that I could pull it out from under the seat to remove the fuse when working on the bike, so no need to remove the seat to pull the fuse. The live side is more in the middle so to get at it I need to remove the seat.

(Edit): The pulley was only a temporary lash up to to support the front of the bike while lowering the front and raise the back up to get the wheel out.  It's certainly not a quick detachable rear wheel (as advertised) when you have to remove the front wheel and lower the front so the bottom of the fork legs are on the ground  *conf*.  Done it a few times and it's always a pain in the ***  *problem*  No excuse for not using a shackle, as a one time yacht owner (*smile* see how the rope is coiled by the ladder) I have a few laying around.
Title: Re: Can anyone identify?
Post by: RoyC on 28.06. 2019 22:22
Page 14, I think  *conf*