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Makotosun

1972 Yamaha LT2 - Restoring the Original Wiring

  • Zyamaha
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That's a good point. I'll add an AC regulator so that I don't blow the LED bulbs that I've got. Looking at te CT2 wiring diagram makes a lot more sense! Thanks for bringing that to my attention. Looks like I basically wired everything like a CT2 anyways, but it will help with troubleshooting the headlight.

I did not have any contact cleaner to try and use on the switch, so I'll have to pick some up. I'm almost positive that the ignition switch is the issue since all of the other points seem to check out okay. I might try taking it apart like you said and see if there's anything obvious. I checked on the backside of the switch already and everything checked out, so if the problem is anywhere, it would be on the inside of the switch.

I'll report back with what I find out. Thanks for the help!
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13 Jan 2022 08:42 #11

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  • Zyamaha
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Hello, it certainly has been a while, but I finally found time to work on it. I used contact cleaner on the ignition switch and found that the switch itself is much more consistent now and seems to be working properly... But the headlight still does not work.

I measured the voltage while the bike was running and found that it was not reading anything going to the "headlight" wire. This wire is connected to the yellow wire in the switch, and also did not have any voltage. I popped off the flywheel magneto and found that one of the previous owners of the bike sloppily soldered all of the wires together instead of having them individually placed onto the condenser.

I also noticed that the yellow wire was completely severed, which would explain why I wasn't reading any voltage. I'm going to reconnect the wires more securely so that this doesn't happen again. I will report back on if the issue is solved.

I do have a quick question about the voltage regulator. At what point would I install this? Would it be between the wire and ground or somewhere else on the circuit?

Thanks again for all your help.
28 Mar 2022 11:53 #12

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  • Gr8uncleal
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Replied by Gr8uncleal on topic 1972 Yamaha LT2 - Restoring the Original Wiring

The Service Bulletin in the Tech Library gives details on this. If it helps, I am attaching the text from a previous post that I made.

"Look for the blue double female bullet connector coming from the main harness and two single male bullet connectors from the speedo and tacho illumination lights.

To save physically cutting and splicing any wires, I made up a small pigtail with a double female at one end and a single male at the other. I fitted the male single to one of the holes in the existing double female and the voltage regulator and single male that I had removed from the existing double female, to the other.

Depending on where you have mounted your regulator, you might have to make up an extension to reach the headlight bucket. I covered this wire on my bikes with some of DEET's silver/grey sheathing. 

The regulator must be earthed. If the frame hasn't been powder coated or given a thick coat of paint, just bolting it to the frame should achieve the earth required."
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28 Mar 2022 12:25 #13

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  • Zyamaha
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Hello!

Just an update...

I was able to get all of the electronics on the bike working by replacing the whole magneto system (I didn't want to solder it and just have it break again later).

I have not installed a voltage limiter yet, but was wondering if anyone had recommendations for which one I should get.

Thanks!!!
28 Jul 2022 22:37 #14

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  • Gr8uncleal
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Replied by Gr8uncleal on topic 1972 Yamaha LT2 - Restoring the Original Wiring

"I have not installed a voltage limiter yet, but was wondering if anyone had recommendations for which one I should get."

I have bought used Yamaha ones off fleabay. I think that Stanley manufactured them, they have a single yellow/white striped wire (although the white is barely visible, so they look yellow) and there are a few styles around. New generic ones are available from online retailers (in the UK, I use Rex).

I have attached images of a couple of the ones that Yamaha fitted. Please note that these get listed under every type of electrical item you can think of (regulator, rectifier, resistor etc), so it is important that you know what you are looking for. And also make sure that it is stamped with 6v! 

I think that forum moderator DEET posted details on how to fit a three wire one, but I'll let others expand on that.

  
29 Jul 2022 00:13 #15

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  • Zyamaha
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Thanks!

I just ordered one similar to that Yamaha one, so I'll get it installed as soon as it arrives (sometime next week).
29 Jul 2022 11:38 #16

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  • Zyamaha
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Okay, so I was able to get all of the wiring done, but now I am having an issue getting the bike to start.

It was not producing spark, but after adjusting the point gap on the stator, it seems to spark consistently now. However, I can still not get the bike to start, even with starting fluid.

It ran fine before I replaced the stator, so nothing else had been adjusted. Is it possible that the timing could be off? I honestly have no idea since it was just a straight swap with no adjustment needed, from what I could tell.

Just curious if anyone knows where I should start.

Thanks!
26 Sep 2022 11:31 #17

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Replied by AirborneSilva on topic 1972 Yamaha LT2 - Restoring the Original Wiring

In my limited knowledge I'd say yes, it's your timing.  There is a specific way of doing it, you may be able to find a youtube video or you can find the procedure in the repair manual.  Up top follow the link to tech library to find a manual that pertains to your bike.
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26 Sep 2022 13:49 #18

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