Main fuse/Positive ground problems

Hi Supercat,
I read some, but not all, of the thread here, so if you have already found the source of the short circuit, forgive me. I had an exasperating short in my "74 Commando that blew innumerable fuses until I found it. The wires connecting to my rear brake switch were behind (and out of sight of) the left exhaust and were intermittently touching the hot exhaust. The insulation was melted away and the bare wire touched the exhaust.
Paul.

Supercat said:

But hold on one sec... here is step 19 from the Boyer instructions:

"19) Connect the white-blue wire (the one removed from the ballast resistor) to the white wire from the transistor box".

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It does, and you could connect to white/blue, but once again, the white/blue is basically a redundant wire once the ballast resistor has been disconnected/removed, so it makes more sense to connect Boyer white to white/yellow (also shown on the Boyer diagram) at the main junction under the fuel tank, because white/yellow 'WY' is what the white/blue 'WU' connects to (below, or see manual diagram) or connect Boyer white to 'switched' white (without the kill button) and if the kill button (WY) is disconnected as you say, then it's likely the WU won't have power unless it has been reconnected to white.

Supercat said:

Are you sure I'm not meant to be connecting the white-purple wire that the PO appears to have used to the white Boyer box wire?

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Yes, I am sure and note the instructions say nothing about connecting anything to white/purple.
Unless the PO has drastically modified the wiring then the Boyer white should be connected directly to white/yellow or white.

Supercat said:

And one more question - if I am able to get spark using the actual wiring instead of the bipass, am I better off running it like that if I wanted to make short trips around town (like less than 5 km at a time), or would I be better of just using the bipass setup while waiting for the new part to arrive?

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If it works when connected correctly, then yes, use it that way as ultimately you will have to, but if in doubt, keep the bypass wiring with you so you can reconnect it in order to get home if something goes wrong.

Thanks L.A.B. and Paul!

Paul, I think I found the short. It seems to be a knackered zener diode. Well, I get an infinity reading on the ohms setting on the multimeter with it disconnected in any case. I'm very happy to be at this stage.

L.A.B., I've order a Podtronics unit from the website that you kindly sent the link for. It's one that allows for running the bike without a battery, which is great. I guess it sort of eliminates the need for 3 bike components (zener diode, capacitor and regulator), and potentially 4 (battery). That's amazing - I can't wait for it to arrive.

I have one more, possibly stupid, question about my wiring situation . Would connecting the white/purple wires to the white Boyer wire, hooking up the battery, turning the key to on, and kicking to check for spark pose any risk to the ignition system, or anything else? I'd like to try this just because it looks like what the previous owner had done, but I'm not doing it if there is any risk.

I see what you mean about connecting the white main switch wire to the Boyer white wire, but I think I would need to cut the white switch wire and make a junction (if that's the right term for turning one wire into two) to get it to the Boyer. It seems to go on up to the front headlight at this point. I'd like to avoid cutting unless absolutely necessary .

Thanks again!!

Supercat said:

Thanks L.A.B. and Paul!

Paul, I think I found the short. It seems to be a knackered zener diode. Well, I get an infinity reading on the ohms setting on the multimeter with it disconnected in any case.

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Infinity reading on VOM implies an open circuit, not a short.

Since you are installing a Podtronics regulator, the Zener will be eliminated, but to determine if it is a possible short, test this way:

Disconnect wire(s) at the Zener tab.
Put red meter lead on Zener tab, black lead on frame ground. Meter should read some low value of Ohms .... 0.5 or so.

Reverse meter leads. Meter should now read infinity.

The Zener is shorted if the meter reads low Ohms with meter leads both ways.
The Zener is open circuited if meter reads infinity with meter leads both ways.

Slick

Thanks Slick I'll try that out.

When I was looking for the short I had the multimeter connected to the main leads that would normally connect to the battery. With the zener connected I was getting 00.0 ohms on the most sensitive setting. That means a short right? When I took the wires off the zener I got infinity.

Supercat said:

Would connecting the white/purple wires to the white Boyer wire, hooking up the battery, turning the key to on, and kicking to check for spark pose any risk to the ignition system, or anything else? I'd like to try this just because it looks like what the previous owner had done, but I'm not doing it if there is any risk.

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No, there shouldn't be any risk, but make sure there are no other white/purples (WP) connected to the ignition coils (or anything else).

If you are determined to try connecting WP to the Boyer, then you must understand that with the ballast resistor disconnected/removed (which it must be for Boyer EI) the normal power feed to WP (from WU) will have been cut off, so for WP to feed power to the Boyer, WP must be (or must already be) connected to another part of the electrical system, the logical options being WY, WU, or W, however, as you've already said the kill button isn't connected, then there will be no electrical power reaching WY (if WY is actually there?) in which case there will also be no power to WU unless WU has been connected to W.

Supercat said:

I see what you mean about connecting the white main switch wire to the Boyer white wire, but I think I would need to cut the white switch wire and make a junction (if that's the right term for turning one wire into two) to get it to the Boyer. It seems to go on up to the front headlight at this point. I'd like to avoid cutting unless absolutely necessary .

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Where is the Boyer box?
White (W) runs from the ignition switch to the main junction area under the fuel tank where it then branches off in different directions.
If the Boyer box is located in the usual place close to the coils (Boyer diagram, Figure 3) then the Boyer box white wire should be sufficiently long enough for it to connect directly to the W junction under the tank, and by doing so, bypasses all unnecessary (WP and/or WU) wiring.

Excellent, thanks L.A.B.! I haven't had a chance to try this yet. I worked late today and it was raining and almost dark by the time I got back so I kept her covered up. I will confirm that they're not connected to the coil before I do anything. I think the ballast resistor is still on there, and the last time I looked it seemed to still be wired. There may even be white/purple wires connected to that. I'll check that before proceeding. I take it that would be a reason to abort my plan .

The Boyer box is in the usual place, but I don't remember seeing the white wire branch off in different directions under the tank. But I wasn't looking for that when I had everything exposed there, so I could have easily missed it. There are lots of wires, and lots of joined wires in that area. I guess one of the main reasons I'm so interested in the white/purple route is because there is a wire with the correct connector all ready to go there. If the white wire branches out and has a ready to go connector also, well... that would be perfect. The possibility of having to cut a wire, make a junction, find a connector and attach it makes me nervous . I'll do it if I have to though. It sounds like I probably won't have to cut or make a junction though, so that makes me more comfortable.

Supercat said:

I think the ballast resistor is still on there, and the last time I looked it seemed to still be wired. There may even be white/purple wires connected to that. I'll check that before proceeding. I take it that would be a reason to abort my plan .

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If you use WP then you need to identify its power source.

If WP is connected to (so being fed from) the ballast resistor :shock: then you certainly need to disconnect it, also disconnect the 'other' ballast wire, normally the WU.

If WU has 12V power (Ign. on) then one option is to connect the WP and WU wires together, another would be to connect WU to the Boyer white as it says in the Boyer instructions instead of using WP.

Supercat said:

I guess one of the main reasons I'm so interested in the white/purple route is because there is a wire with the correct connector all ready to go there. If the white wire branches out and has a ready to go connector also, well... that would be perfect. The possibility of having to cut a wire, make a junction, find a connector and attach it makes me nervous . I'll do it if I have to though. It sounds like I probably won't have to cut or make a junction though, so that makes me more comfortable.

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You may have to fit a bullet connector to connect Boyer white to W.
Removing unnecessary connections and lengths of wire generally helps to increase reliability especially where EI is concerned as they need a good electrical supply with no poor connections which is my reasoning for connecting the Boyer directly to W, but it's up to you.

In the interests of reliability, if it still has the original rubber junction block then I'd seriously suggest you replace it (or use separate double common etc. connectors, see BritishWiring link, below) also renew all the other 'bullet' connector sleeves on the bike as they are usually corroded and the internal metal tubes have often become brittle from age and can break up unseen inside the rubber sleeve.

concours said:

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http://www.britishwiring.com/category-s/266.htm

Thanks a million L.A.B.!!!

I'm hoping to get to spend some proper time at the bike tomorrow, and I'm going to head out now shortly just to have a look at the wiring to see where the white from the main switch goes when it gets to the gas tank. I have a feeling the original rubber junction block is probably gone. There is a bit of a mess of bullet connectors along the left side of the top of the frame under the tank closer to the headlight. That situation definitely doesn't look stock, to my untrained eye anyway.

If I was able to get spark through the main harness instead of my bipass setup, would leaving the alternator disconnected eliminate my risk of damaging the ignition and the battery due to overcharging? I can wait till my part shows up before re-connecting the alternator.

K, I've just had a look, and the original rubber junction appears to be gone. It may be buried in the mess of bullet connectors I mentioned, but if it's there it's not obvious. There are also still white/blue and white/purple wires connected to the old ballast resistor.

I did notice that there is a double set of white wires that are not connected to anything that seem to come from the main switch and that end with a connector that dangles just in the rear end of the battery box. Are those good candidates for connecting to the Boyer white wire? Should I connect the battery and use the multi-meter to look for power on those with the switch turned to on? I could run a wire from those up to the Boyer box wire fairly easily and that wouldn't require any cutting. I could even use my negative bi-pass wire to make that connection with relative ease. It's plenty long enough.

Supercat said:

would leaving the alternator disconnected eliminate my risk of damaging the ignition and the battery due to overcharging?

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Yes, but from what you've just said, it seems you have a fair bit more tidying up of the electrics to do yet.

Supercat said:

K, I've just had a look, and the original rubber junction appears to be gone. It may be buried in the mess of bullet connectors I mentioned, but if it's there it's not obvious. There are also still white/blue and white/purple wires connected to the old ballast resistor.

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Well, as I've said already, those two wires definitely need to be disconnected from the ballast resistor if you intend to connect WP (or WU) to the Boyer box white.

Supercat said:

I did notice that there is a double set of white wires that are not connected to anything that seem to come from the main switch and that end with a connector that dangles just in the rear end of the battery box. Are those good candidates for connecting to the Boyer white wire? Should I connect the battery and use the multi-meter to look for power on those with the switch turned to on? I could run a wire from those up to the Boyer box wire fairly easily and that wouldn't require any cutting. I could even use my negative bi-pass wire to make that connection with relative ease. It's plenty long enough.

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Yes, you could do that, but I suggest you try to find another available source of power closer to the Boyer, first.

Man, thanks so much L.A.B.!!!

I'll pick up some zip ties and some more electrical tape in the morning and will try a few things out. It'll be nice to see if the parking light works first off. Then I'll see if I can find a white wire closer to the Boyer box to connect the Boyer white to as you've suggested. If that looks like it'll require any cutting I'll check the rear white wires to see if they have power and will consider trying to connect to them if it seems doable. Then I'll do some tidying with electrical tape and zip ties for now. I'll order some bullet connectors as you've said and will do things properly (or at least as well as I can with my rudimentary skills) when those arrive. I've got to head out of town for a few weeks on Monday so I'll have to put the bike away for a bit until I get back.

Hoping to get out for a short ride or two over the weekend, and be able to drive it into my shed before I travel. If I end up able to get spark in the normal way (i.e. not using the bipass), I'll leave the alternator disconnected until the Podtronics unit arrives.

Hi there,

Ok, I've connected the battery to the main leads - I'm no longer blowing fuses, which is great. The parking light works in the main headlight with switch setting 1 & 4. The horn doesn't seem to be happening when I press either the top or bottom buttons on the handle bar. The main front light doesn't seem to be coming on, but maybe it's not meant to until the bike is running?

The weird thing is that I'm getting fluctuating voltage readings from both the white/purple and the white set of wires at the back of the battery box. Box will sometimes go up to 12 v or a little higher (the battery is reading 12.56 or so), but they often just drop down to 7 or 8 volts and sometimes down to between 2 and 4 volts with they key in the daytime riding position. This makes me weary of trying to run the bike through the harness at the moment. I expect readings like that would be great for getting kickback, which I do not want. Any idea what would cause that?

From my notes, the white/purple is between the ballast resistor and the coils. Where are you finding it?

Supercat said:

The main front light doesn't seem to be coming on, but maybe it's not meant to until the bike is running?

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The headlamp runs off the battery, so it should come on at key position 4 regardless of whether the engine is running or not.

Supercat said:

The weird thing is that I'm getting fluctuating voltage readings from both the white/purple and the white set of wires at the back of the battery box. Box will sometimes go up to 12 v or a little higher (the battery is reading 12.56 or so), but they often just drop down to 7 or 8 volts and sometimes down to between 2 and 4 volts with they key in the daytime riding position. This makes me weary of trying to run the bike through the harness at the moment. I expect readings like that would be great for getting kickback, which I do not want. Any idea what would cause that?

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Have you disconnected WP from the ballast resistor? If you have, then what is WP connected to that has power? If you haven't disconnected WP from the ballast, then you are wasting your time.
If you are getting fluctuating voltage readings there could be a bad connection somewhere, possibly inside the ignition switch.

I see my question about white/purple is being addressed by LAB. There are lots of reasons to listen to him instead of me. Not the least of which is that I have never seen a Boyer. His comment about the ignition switch is valid. I have one apart in front of me right now. It would appear that something I sprayed into the key slot to lube and clean it was not very friendly to copper and brass. The contacts for the brown/blue from the battery where green. So its no wonder that when I fired up the bike it acted like it had a carb issue!

Russ

rvich said:

From my notes, the white/purple is between the ballast resistor and the coils. Where are you finding it?

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Although not shown on the wiring diagrams, a WP and a white/red 'WR' normally run through the harness to the battery compartment as those two wires would have been connected to the electric start solenoid if the factory had fitted the Lucas version starter motor in 1971. :wink:

WR would have been the solenoid operating wire from the handlebar switch cluster push button (which has the WR wire and is shown on the wiring diagram going nowhere) and WP would have been the ballast 'bypass' (solenoid-to-coils) wire.

L.A.B. said:

rvich said:

From my notes, the white/purple is between the ballast resistor and the coils. Where are you finding it?

Click to expand...

Although not shown on the wiring diagrams, a WP and a white/red 'WR' normally run through the harness to the battery compartment as those two wires would have been connected to the electric start solenoid if the factory had fitted the Lucas version starter motor in 1971. :wink:

WR would have been the solenoid operating wire from the handlebar switch cluster push button (which has the WR wire and is shown on the wiring diagram going nowhere) and WP would have been the ballast 'bypass' (solenoid-to-coils) wire.

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All I know from my notes is that I removed the white/purple from the harness when I installed the EI. I am a little puzzled about the ballast resistor still having power to it. Could that be causing the low voltage readings? Seems like removing all that is a good way to go, or so I thought when I did it.

Russ

rvich said:

All I know from my notes is that I removed the white/purple from the harness when I installed the EI.

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Yes, as removing, or disconnecting it would be the normal thing to do, however, Supercat appears insistent on using the 'wrong' wire = WP, to power the Boyer because it has the 'right' terminal on it. :?

rvich said:

I am a little puzzled about the ballast resistor still having power to it.

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Theoretically, it shouldn't, as it should have been disconnected :roll: therefore WP shouldn't have any power in it at all.

rvich said:

Could that be causing the low voltage readings?

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Possibly the WP, but he said it was also the white in which case it's less likely to be the ballast resistor causing the drop/fluctuation in voltage.

rvich said:

Seems like removing all that is a good way to go, or so I thought when I did it.

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My feelings, exactly, but it seems I'm having some difficulty convincing Supercat.

Well the Boyer certainly wont care which color the wire is going to it, so if the WP is going to be used to power it then it needs to be hooked the white somewhere that doesn't include the ballast resistor!