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I have rebuilt a 1976 R100S that was in a partial state if disassembly when I got it, especially the wiring. Im just at the stage where I am trying to figure stuff out and what goes where.

I have a couple of questions, firstly, I have a red wire that is permanently live but I cannot find a home for it. It come from about the middle of the loom and seems to be a direct link to the main battery positive cable.

The second one is, I am sure that I need a wire to this connector on the starter solenoid, should this come from the starter relay?

Please see the pictures.

Many thanks, Daniel.

Maybe this will help. It's for a different year, but it should be mostly the same as your bike.

Does the wire itself come out of the loom? With that hardware store terminal, it looks like it might be an addition.

See if it reaches the starter relay area--it could be the power source for the relay (terminal 30) or for something that was added, like a horn relay.

The spade on the starter gets a black wire from the starter relay, from terminal 87.

Now if your bike is a 1977 model, the colors and terminals on the starter relay are reversed. Red to 87 and black to 30. But those are just the opposite ends of the switch inside the relay. There's also a red wire to 87a for 1977 which powers the light relay in the headlight bucket. This would be just like gspd's wiring diagram above.

OK, so the red wire with the yellow DIY terminal does come from the loom, I will take a picture tomorrow but it looks to come from the main positive wire from the battery. It is live all the time yet I have no power to anything else, lights, horn or starter. I feel that this wire, with the yellow terminal end, is key to livening up the loom.

Mine is a 1976 model but I can check about the black wire coming from the starter relay, also, tomorrow.

Are all the spades spoken for on the starter relay? That should be a silver can on the left side of the frame.

I ask about 1977 because R100 started with 1977 models. 1977 models started production in September of 1976.

Ah interesting how a conversation brings new things to the issue I am having. I went out and took a couple more pictures.

I have this and I don't know what it is but it doesn't seem to be related to the starter issue.
But this is a rework of the starter relay by the looks of it.
I now see a terminal on the starter relay that is empty and I wonder if the "hot" wire should go there.

OK, the first box you posted up there was the voltage regulator which lives on the right side of the frame, usually. The smaller unit is the starter relay and it looks like you actually have a 1977 model.

The red wire probably goes into the slot you've highlighted. The hardware store terminal doesn't have the 'catch' on it that would otherwise hold it in the plastic block. If you pull the actual relay off that block, the open spade will probably be 87 or 87a.

The numbers on that unit suggest some kind of fuel pump relay. Where do the other wires on the "relay" go? That could help determine just what it is.

Kurt

melville wrote: ↑Thu Sep 29, 2022 1:45 pm OK, the first box you posted up there was the voltage regulator which lives on the right side of the frame, usually. The smaller unit is the starter relay and it looks like you actually have a 1977 model.

The red wire probably goes into the slot you've highlighted. The hardware store terminal doesn't have the 'catch' on it that would otherwise hold it in the plastic block. If you pull the actual relay off that block, the open spade will probably be 87 or 87a.

Brilliant, I'm done for the day a couple of hours ago but I'm now excited to get back to it in the morning.

I really appreciate your help. Just chewing a problem over with someone, where ever you are really helps.