1971 Build for Dad

It sounds like the easiest solution would be to scrap the blue park wire coming from the ignition. Just don't even connect it.

Then, the red/yellow wire from the ignition could be sent to the headlight switch, possible with an inline fuse to protect the 20A. Alternatively, would it be possible to just feed the headlight switch from the fuse box (i.e. the brown ignition wire supplies all power)?

In either scenario, the blue taillight/meter wire would be coming out of the headlight switch. Would that work?
 
Yes, eliminate the blue wire for the parking light feature from the main switch and there will be no feedback issues. Yes, you could feed the headlight on/off switch power from the fuse box. That's how the fuse box models are set up. They have a 10A headlight fuse and send headlight power out on a red/yellow wire. But, you're trying to combine newer components with older ones and that's where the issues are cropping up. The newer bikes that had the fuse boxes didn't have a headlight on/off switch (well, most of them anyway). Headlight power was sent to the headlight auto-on safety relay. That relay was tripped once the motor was started and that allowed the power to continue on through up to the headlight.
 
No, that wouldn't help either. The problem is two different sources (ignition switch and headlight on/off switch) feeding power to the same destination, the tail light. Even if both were on separate fused lines, power into the light on one would just feed back through the other at the light.

OK, got it.............so really its the R/Y that is feeding the power back to the fuse box when the Light switch is turned on............Why not go back to the original diagram, (74TXA), and just have the R/Y going from the ignition to the ON/OFF switch. It is only used/power when the ignition is turned to Park, bypassing the fuse block......Don't need to fuse that R/Y wire anyways.
 
The newer bikes that had the fuse boxes didn't have a headlight on/off switch (well, most of them anyway). Headlight power was sent to the headlight auto-on safety relay. That relay was tripped once the motor was started and that allowed the power to continue on through up to the headlight.
A bit of good luck here... The switch blocks I am using do indeed have an on/off switch for the headlight, which does seem like a bit of an oddity, as my '80 has no such switch (despite looking the exact same):

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And despite the poor documentation that came with the blocks, that switch has the blue/black, red/yellow, and blue wires referenced in the original diagram!

I finished going through the other switches/wires and think everything else should be good to go. The headlight dimmer switch has several wires not included in my diagram that are intended for use with the headlight relay/reserve lighting unit, but I think I can get away with only connecting the main wires. Will get out the multimeter and confirm this... I was also surprised to learn that my indicator light on the tach is for signals, not the high beam :doh:.

I will post a revised copy of the diagram when I get it updated.
 
The '78 models were the last ones that came with that headlight on/off switch. They were also the first model with the headlight auto-on safety relay. This somewhat crippled the headlight on/off switch operation. It only functioned with the key on, motor not running. As soon as you started the bike, the safety relay kicked in and bypassed the handllebar switch, turning the headlight on. I thought that was a rather silly set-up so I "fixed" mine, lol. Studying the wiring diagram revealed this very simple work-around .....

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My headlight safety relay is, no doubt, still doing it's thing but now the power it was sending to the headlight isn't going anywhere. This has restored the full time, all the time function of the handlebar on/off switch.
 
To me the solution is simple, have a parking light by cutting the thinner Blue wire, or don't have a parking light and just cut the thick Blue wire.
 
don't have a parking light
Agreed! Best just to get rid of the damn thing...

Here is the latest version of the diagram. Edits include updating the ignition switch configuration, signal indicator lamp wiring, and blue wire taillight power. At the end of the day there is one master fuse and all other major systems are individually fused. I get this may not be strictly necessary, but I figure since I have the space and am looking at a custom harness anyways I might as well make the most of it. Maybe it will save me from walking home one day... Anybody see any issues?

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Anybody see any issues?
The brown from the iggy sw now carries all the power, including the headlight. The headlight power previously came directly from the iggy sw. That's not a problem, but I'd go up one gauge on the brown wire to carry that extra load.... 16.. maybe even 14 ga wire.

Blue from the fuse to the taillight. That means the taillight will be powered as soon as the key is turned on. Again, not a problem if you don't mind that. You could just take that blue and tie it to the other blue from the light sw.... just do away with the 5A fuse and let the headlight 10A carry it. Or.... just let it be.
 
Yes, I was going say now your tail light will be on all the time, any time the key is turned on. Tie it into the blue coming out of the headlight on/off switch instead and you will have control over it. But, I don't consider it a big deal having it on all the time, especially if you put a LED bulb in it. The draw will be next to nothing. My '83 was another story. By then, Yamaha had "updated" the tail light to a 2 bulb unit, and also had a separate license plate light with 2 more bulbs. So, turning the key on was lighting 4 bulbs. That did bother me so I changed it. I tied them into the headlight on/off switch I added instead. And, I thought everything was golden until this feedback issue was explained here, lol.
 
I was thinking the same on the thicker wire. I was also thinking of splicing together the brown and red/yellow from the ignition pigtail into a thicker main wire - to distribute the load more within the switch. Same source, shouldn't be a problem, right? That or maybe try to crack open the ignition switch and directly solder in a new wire?

Two reasons for the taillight. Firstly, it will be much closer to the fuse box than the blue coming off the headlight switch. I was also thinking that it would be an indicator, in case I walked off with the ignition on or something like that.

Think I am going to leave it be unless there are any other issues. This makes the most sense to me. Thanks to everyone for walking my sorry-ass through this! I do feel like I have learned a good deal in the process.
 
Seems all good progress, well done Rhy650. The next part is to work out where to fit all the connectors in the headlight area. Regarding crimp connectors, quality always pays off.
 
Thanks. I think I am in good shape regarding the connectors. Dad had already purchased a bunch of bullets, connectors, and a set of crimping pliers from vintageconnections.com. They look to be of good quality.
 
Quick question.. Where were the factory frame grounds on the XS1B? I know one is at the top engine mount, but isn't there another one around the battery? Can't find it and wanted to double-check before I get the drill out and make my own.
 
+1 on the Vintage Connections supplies. I bought and used them and they are quality pieces. Word of advice... practice putting ends on some spare scrap wires first. There are two crimp "tangs" on the connectors. One crimps around the insulation and the other crimps the bare wire. It takes a few tries to get it right. Also, on the tang that crimps the insulation, a good tip is to bend the tangs inward a little so they are not parallel with each other when you insert them into the crimping tool. This just helps them to bend into the dies a little easier when you squeeze the crimp gun.
 
+1 on the Vintage Connections supplies. I bought and used them and they are quality pieces. Word of advice... practice putting ends on some spare scrap wires first. There are two crimp "tangs" on the connectors. One crimps around the insulation and the other crimps the bare wire. It takes a few tries to get it right. Also, on the tang that crimps the insulation, a good tip is to bend the tangs inward a little so they are not parallel with each other when you insert them into the crimping tool. This just helps them to bend into the dies a little easier when you squeeze the crimp gun.
To add to that, after every crimp...every crimp, give the wire a good tug and make sure it doesn't pull free. If it's a bad crimp, you want to know now and not 100 miles from home.
 
To add to that, after every crimp...every crimp, give the wire a good tug and make sure it doesn't pull free. If it's a bad crimp, you want to know now and not 100 miles from home.
:agree:
Contrary to popular belief, you won’t get a good crimp with pliers or Vice-Grips.
 
practice putting ends on some spare scrap wires first.
Yep, I definitely botched the first couple. Once I got the spacing right I am very pleased with how tight they hang on to the wire/insulator.

My guess is your XS1B battery grounds to the motor, same as my XS2.
Perfect! I probably should have thought of that... giant metallic object with countless through holes...
 
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