I posted a while back asking for help with sorting out a wiring diagram. This feels a little like the final submission of a research project (which has taken me several weeks). I have purchased and have been reading Classic Motorcycle Electrics Manual by James Smith; very detailed and informative but didn't quite take me to where I wanted to get to. I have been using wiring information that came with the Wassell Vape electronic ignition and from the Lucas Reg/Rec and from original BSA 250 wiring diagrams. I have also been very grateful for the videos posted on YouTube by Brian Stretton, who has been recording his work on a BSA Starfire which at times has been exactly what I have been looking for.
Following a lot of head scratching and sitting in a dark room with a wet towel around my head I have arrived at the attached which I now submit for review by the BSA Forum; please be gentle with me! I have a version of this with the coloured wiring but that did not reproduce too well, so I drew it out again in black and white.
If you can help me, I will be very grateful,
Rev Kev
I perhaps should have added that the bike is a C25 (1967) but will be wired similar to a B25 Starfire (1969-70)
Looks ok to me but is there any reason for connecting the stop lamp circuits to the permanently live side of the ignition switch?
Seems quite clear and logical although it isn't clear which wire is connected to which terminal on the ignition switch, or what the lighting switch connects/disconnects in various positions. Um, it's probably quite clear to you.
Thanks Derek996 and Rog1,
The ignition switch that I have has 4 spade-terminals at the back. In my ignorance (because I couldn't find out how the switch works from internet searches and from my reading) I assumed that when the switch is off and the key is out all 4 terminals are disconnected i.e. dead. Again, I assumed that once the key is in and the ignition is on all 4 terminals are connected and so live; I assumed that I could route all circuits through the ignition switch as this would disconnect all circuits. From your post I conclude that I am wrong and the 4 terminals need to be wired in a particular way (?)
Re the lighting switch, I have taken the live to terminal 4 as I would then be able to disconnect the power with the switch in position 1 (which links terminals 1 and 7 so not making a circuit in how I am proposing to wire the switch). The middle switch position (which links terminals 1, 4, 6 and 7) will give me pilot and tail. The fully on position (which links terminals 1, 4, 7 and 8 ) gives lights through the dipper switch and tail light. This was an arrangement that I have seen in one of the wiring diagrams I found (page G17 from the BSA Manual for later B44s and B25s; see attached) and it seems to be work better than having the live connection come in on terminal 1. Is there a standard way of wiring this switch that I have missed?
Thank you for your feedback, this is really helpful,
Rev Kev
Also, how do you earth a Wipac Ducon switch for the horn? There doesn't seem to be enough wires from the switch and no clear instruction about how to earth the horn.
Not familiar with the Wipac switch but the usual practice is to take a live feed to one terminal of the horn. The other horn terminal goes to the horn switch which earths through the handlebar when the button is pressed, thus sounding the horn.
The lighting switch is fine.
I don't know about the ignition switch so cannot be sure. Do you have a multimeter? If so, you can check what is connected in the various ignition switch positions and let us know. You can also check with some sort of battery and bulb setup. How many switch positions are there?
Multimeter! Why didn't I think of that? Derr! Thanks for the idea. Looking at the back of the ignition switch there are 4 spade terminals but these are "U" shaped pieces of copper so 1 and 2 are permanently connected as are 3 and 4. Looking at the wiring diagram I do not want to have either the light switch permanently connected to the live feed from the battery; even though this would be OK as the light switch would break the circuit but it would not stop any passer by switching the lights on and draining the battery when the bike was parked. Having the brake light permanently live would not be such a problem; the light would only go on if someone stayed with the bike and held the brake on; this is similar to my Norton Dominator. However, I think that I will pair the live feed from the battery with the feed from the electronic ignition transistor box; as the engine would not be turning there would be no feed from the stator plate.
Having checking with the multimeter all 4 terminals are live when the ignition switch is in the on position, which was the only obvious answer.
Thank you Rog1 and Derek996, this has been really helpful - does anyone else have a view on what is being proposed? If so, it would be great to hear from you,
Rev Kev
In that case, I would put the feed from the ammeter on terminal 1 or 2, the lights on (say) 3, and everything else on 4, including the electronic ignition and maybe the brake light. The lights are the biggest current draw so they get a terminal all to themselves.
The wire to the ignition switch from the electronic ignition can't be permanently live as it would drain the battery and make the coil get hot, plus the ignition switch wouldn't be able to stop the engine. It's up to you if the brake light circuit is permanently live; it's like that on my BSA and I don't find it an issue. If you go for permanently live, you can connect it to the spare terminal on the ignition switch if you like.
You might know all this, but...
If you have one of those cheap, (£6) common, pressed steel wire stripper/crimper/side cutter tools don't use it; they do not produce reliable crimps. Ratchet crimpers for non-insulated terminals are the tool to use. They are a good £32 more than the £6 ones but if a crimp fails and you are stuck on the side of the road you'll wish you had used them. The non-insulated terminals are very reliable and have separate insulation (bought separately) that you slip over the wire before crimping. The red/yellow/blue insulated crimps aren't as reliable but you need another, different ratchet crimper for them. I will be rewiring my M33 mostly using British style bullets, but I'm going to solder them; I'm not good at soldering but I can manage them okay.
Here's where I get stuff from:
https://www.vehiclewiringproducts.co.uk (https://www.vehiclewiringproducts.co.uk)
Thanks Rog1,
This is, again, really helpful and I will take your steer about having the brake circuit on the permanently live side.
I have read about the cheap stripper/crimper etc tools. As this is the only wiring loom I am ever to assemble I was hoping that one of my biker mates might lend me one or other wise I will solder all the connections but this will mean that I will have to "dry" assemble the loom without the space connectors as I want to use sleeving to protect the wires. The advantage of the crimped connectors is that you can easily fix connectors with the loom on the bike; I don't fancy trying to solder in the same way - I will have to think about that.
Thanks to you and Derek for your comments; this has given me the confidence to proceed,
Rev Kev
Just had a look at this website - https://www.autoelectricsupplies.co.uk/p/crimping-tool-for-non-insulated-terminals-standard I think that I will go for the crimped connection,
Rev Kev
Great; let us know how it all goes. I haven't come across AES before, so I've bookmarked your link for later reference.
AES were a recommended supplier in James Smith's book "Classic Motorcycle Electrics Manuel", which is an excellent book for anyone who wants to really go back to basics. However, some (including myself many times) can find that he focusses a little too much on the theoretical. I did need to take notes and keep these under review during the first few chapters.