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#844461 03/29/21 12:44 pm
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Hello,

First time poster. I've got a 1965 C15 that won't start.

There's no spark, so it's obviously not starting. I'm pretty certain the timing is set correctly. I've made sure to check this a few times to make sure as it was my first time doing this. Frame to engine earth is tested and good.

The wiring harness is all new, so I have a good starting point in knowing that the colours are all correct. I'm trying to convert it to 12 volts and have fitted a combined reg/rec (Podtronics type), 12 volt coil and have swapped out the bulbs.

I've got the Rupert Ratio books showing the wiring diagrams, but wanted to get some advice from someone that's actually done the work and can help more practically! I think I need to rewire the ignition switch, but I'm not entirely sure how. My new wiring is as page 185 and to convert to 12 volt is page 186 I believe.

Any help and pointers would be greatly appreciated.

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Sidepoints F type engine ? or earlier Distributor engine ?

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Yes, it's side points F engine.

Thanks for the reply

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Have you swapped the alternator for a 12v 2 wire type? Or are you still using the original one? If your using the original 3 wire alternator have you paired two of the wires together or do you still have one wire going back into the loom(green and black??) for emergency starting?


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Hi Allan, thanks for the reply.

I'm on the original alternator. I've joined the black/green and green/yellow wires together which run to one of the yellow wires on the reg/rec. The green/white wire runs to the other yellow wire on the reg/rec.

Is that right? Does it matter which yellow reg/rec wires, or is that irrelevant?

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Have you had the engine running with the original 6V system? This will give you an indication that the engine and carb were functional at that time.

The alternator/Podtronics don’t need to be connected for the engine to start.

What is needed is a good 12V battery, fully charged and displaying ~12.6V, and that this voltage is reaching the coil –ve when ignition switch is on.
There must then be good continuity from coil +ve to the moving contact, and a return path from the fixed contact to the battery +ve.

Then provided there is a contact gap when fully open of ~15 thou, you should get a spark, whether the timing is accurate or not.

So you need to check that basic circuit and do what is necessary to get it sparking before worrying about anything else.
Connections, condenser and contacts are principal suspects.

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Hello, thanks for the reply.

I did have it running on the 6 volt system prior to this. I've had the engine apart since then to cure some leaks and clean the crank out. Coil, condenser and points are all new replacements, but I'm not ruling then out and understand I need to check them.

I understand what you're saying but a little confused as to how to do it and how to check each thing.

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Hi,
I’ve not seen you mention a 12V battery so far, you do have one installed?

As you’ve checked “Frame to engine earth is tested and good.” I assume you have a multimeter? So what voltage is the battery showing?

Before getting that involved, I would suggest a crude test of the ignition circuit in isolation.

Just in case there is a mis-connection in the new harness installation, disconnect the existing connection of the harness from the battery –ve.
Also disconnect the existing harness connection at the coil –ve.
Position the engine so that the contacts are closed.
Now connect a separate wire from the coil –ve, flash the other end on the battery -ve. You should see sparks at the battery terminal. If you don’t, there is something not conducting in that minimal circuit that needs to be corrected.

If it does spark in the above check, then with the sparkplug laying on the head (in its HT cap of course) then hold or fix the “hot wire” on the battery –ve and turn the engine (or just open the points with your fingernail). You should see a spark at the plug.

Try the above before going any further.

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I think I made sense of most of it. It's not you explaining it, it's me being thick.

I tested coil positive to moving contact with a test light and it was ok. battery positive to fixed contact was also ok with the test light.

My battery is good and fully charged. How would I go about checking the power from the battery to the coil?

Also, I did try to get the bike running before with the old wiring as 12 volt, but I didn't have any luck. Hypothetically, if I'd wired it up wrong then, could I have damaged something in the system?

Thank you for the replies.

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I doubt that you have damaged any ignition components by trying your new components on the original harness.

The use of a test light (rather than a multimeter) can only inform to a degree.

Knowing now that you only have that to help with diagnosis, I think that it would be worth following the suggestions in my previous post.
Follow one line at a time carefully:

[Disconnect the existing connection of the harness from the battery –ve.

Disconnect the existing harness connection at the coil –ve.

Position the engine so that the contacts are closed.

Connect a separate wire from the coil –ve, flash the other end on the battery -ve.
You should see sparks at the battery terminal.
If you don’t, there is something not conducting in that minimal circuit that needs to be corrected.

If it does spark in the above check, then with the sparkplug laying on the head (in its HT cap of course) then hold or fix the “hot wire” on the battery –ve and turn the engine (or just open the points with your fingernail). You should see a spark at the plug.]

The above shouldn’t take more than 15 minutes or so.

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Sorry, I completely missed your reply before my last reply. We must have posted about the same time!

I'll get a multimeter tomorrow and have a look through what you suggested again to get a better idea. Thank you for your help.

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What I suggested was an elementary test (multimeter not required) which would have provided basic function information (ie that the ignition system works or not).
The sort of test you could do by the side of the road with a length of wire, if the ignition switch (or any other connection) was suspected of causing a problem.

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Originally Posted by courtney
Hi Allan, thanks for the reply.

I'm on the original alternator. I've joined the black/green and green/yellow wires together which run to one of the yellow wires on the reg/rec. The green/white wire runs to the other yellow wire on the reg/rec.

Is that right? Does it matter which yellow reg/rec wires, or is that irrelevant?

Sounds about right to me.

The importance which koan might be missing from my question is my follow up two questions... did you isolate the wire which connected originally to the green/black wire?

Also, are you switching the ignition switch to the correct position? My bantam had emergency and standard ignition positions, for a long time when on 6v I selected the wrong position, it never seemed to make any difference. When I converted to 12v it still worked just the same but I didn’t know if the c15 wiring was different in some way.


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Hi Allan,

The wire is hanging out of the way, so shouldn't be causing an issue. The C15 does have the emergency position and the normal position and I had it turned clockwise, which I'm pretty sure is the normal position. It did make a difference at 6v but I believe it's defunct and bypassed at 12v on the C15.

Unfortunately, the switch stopped turning clockwise earlier and I ended up getting the key stuck, so I'm having to order a replacement before I can begin to get it running again.

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Hi Allan,
“The importance which koan might be missing from my question is my follow up two questions... did you isolate the wire which connected originally to the green/black wire?”

The whole point of my procedure was to remove such complexities from the situation, to reduce it to just a simple test of the ignition system, to established if it works (or not).
If you follow my instructions, it is just a simple battery/coil/points ignition, which is how it is intended to work in normal circumstances.
The alternator, or any permutation of the alternator leads, are not involved in that test.

If that test shows that the ignition system works, it then shows that the problem lies within the ignition switch or the wiring between battery to it, or from it to the coil.

Some of the original system wires are now redundant in the 12V system, and from what I've just read, there are other issues with the switch.
I still think it would be a good idea to establish whether the ignition system works independently of the complex and possibly faulty original switching arrangement.

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It was a bit of a bugger with the switch. I checked all it's positions earlier in order to rule out that as an issue, and then it just stopped turning clockwise later for seemingly no reason. Oh well.

Last edited by courtney; 03/29/21 9:44 pm.
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Originally Posted by koan58
Hi Allan,
“The importance which koan might be missing from my question is my follow up two questions... did you isolate the wire which connected originally to the green/black wire?”

The whole point of my procedure was to remove such complexities from the situation, to reduce it to just a simple test of the ignition system, to established if it works (or not).
If you follow my instructions, it is just a simple battery/coil/points ignition, which is how it is intended to work in normal circumstances.
The alternator, or any permutation of the alternator leads, are not involved in that test.


Hi Koan, I didn't realise we were in some kind of competition with the questions and advice being given?

Knowing that the wiring would have been somewhat changed, it would be worth while asking such questions relating to the charging system. In the 6v system, one set of stator coils would feed the emergency side of the ignition switch, this has now been disconnected.

A follow up question would be to check that 12v is being found at certain points. I'm sure you'd agree that its best to work backwards... So checking voltage at the negative side of the coil against the positive on the battery... does this work with the key/switch in either position? (on my bantam it did)

If not then you work backwards, to the output side of the switch and +ve on the battery (to check the cabling) and then to the ammeter if one is fitted and keep working backwards until you find 12v, this might only be at the battery.

Originally Posted by koan58
there are other issues with the switch.
I still think it would be a good idea to establish whether the ignition system works independently of the complex and possibly faulty original switching arrangement.


I agree, I never said that I didn't (or at least I don't think i did?). A jumper wire from the negative side of the battery to the negative side of the coil would instantly solve that question. unless the condenser has become disloged and then you'll never get it started.

It would also be worth confirming the battery voltage.


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Hi Allan,
There’s no advice competition as far as I’m concerned.
I was merely directly addressing what Courtney presented as the problem in the first 2 lines of his first post:

“I've got a 1965 C15 that won't start.
There's no spark”

ie. That the ignition system isn’t doing its job.

This could be due to faults in the ignition system itself, or faults in the power supply to the coil (such as ignition switch and correct wiring connections from battery –ve to the ign sw on to the coil), or faults in both areas.

Bearing in mind the OP’s uncertainties about wiring the new harness in (those original 6V system rotary switches require thoroughness in correct connection, as you know), I simply considered it expedient to take all other possible errors out of the equation by disconnecting the harness and testing the ignition system in isolation, to establish whether the ignition system itself is functional.

Hopefully with pretty-much all new components, it would produce a spark at the plug.
If it did, the investigation could then move on to the feed from battery –ve, via ign sw to the coil.

OP:
“My battery is good and fully charged. How would I go about checking the power from the battery to the coil?”

Having established OP didn’t have a multimeter, I didn’t offer any voltage-chasing advice, instead offering a direct method of getting battery power to the coil.
Even if the battery isn’t quite as good as OP believes, it should do for this test on a breaker system.

Of course there may also be faults in the charging system wiring, which would be apparent once the engine can be started.

Hopefully OP will have obtained a multimeter soon, so more detailed investigation will be possible.

Cheers!

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Hello again,

Today I tried the negative battery/ coil thing. There were sparks at the battery and I also got a spark at the plug trying the second part of the suggestion. I also have a better understanding of how it all works now, which I appreciate.

I got a multimeter yesterday, though not much idea of how to use it for the most part, so I've been looking on YouTube which is a bit hit and miss.

New ignition switch should be delivered tomorrow. What to try next?

Many thanks for the assistance again.

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Good news Courtney! That proves there is life in the ignition system. You should be able to start your bike on the battery now, if any encouragement were needed, that would give you a boost!
I'd suggest you do that, so you know that not only is the ignition system working, but the engine and ignition timing is also good.

Then when you install the new ignition switch you know what to hope for.

With the new ignition switch, in the 12V system, several of the wires between it and the light switch aren't required.
The ignition switch only requires the battery -ve feed, and then to send it onwards to the coil and the light switch.
Other connections are redundant.

I think you're making progress!

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Thank you again for your help.

I got it running today! It was right at the end of the day and had to pack stuff away, so I will have a better look and sort things out with the switch and lights, and re-check the timing on Saturday.

I appreciate all the replies from all that helped. I'll probably be asking a question about the lights, but maybe it'll go smoothly.

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I've been back at work, so not had as much time to try to work on the bike this week. I had a chance today though.

After getting it running last week by connecting the negative coil and negative battery terminal, I was unable to get it started today with the ignition switch and other bits in the system and there's now no spark. The ignition switch has now been replaced with a new one since last time when it broke, as mentioned in my previous replies.

Looking at the wiring diagram in Rupert Ratio for the 12V conversion, it seems that there's only two wires coming from the ignition switch. Koan and others have said that a lot of the wires from the ignition switch don't need to be connected, so I'm aware that some are now redundant.

[Linked Image from i.ibb.co]

Has anybody on here done the work and know what wires go where? The wiring loom is new, so I'm reluctant to start peeling tape away and unravelling things until I'm sure. Much of the wiring looks the same but there's a couple of bits I'm unsure of from standard.

Any help much appreciated. Thank you

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The only wires/connections involved in ignition are:

- the brown/blue (NU) from battery –ve to ammeter

- the brown/white (NW) from ammeter to lightswitch 2

- lightswitch 2 is permanently internally connected to lightswitch 10

- lightswitch 10 then connects via brown/white (NW) to ignitionswitch 12A

- when the ignitionswitch is ON, ignitionswitch 12A connects to ignitionswitch 13.

- Ignitionswitch 13 then connects via white (W) to the coil –ve

From your earlier experiment, we know the system works from there onwards.

So something in the above routing is incorrect and preventing the battery –ve voltage reaching coil –ve.

As you now hopefully have a multimeter, set it to DC volts in the range above 12V (probably 20V?), fix the red probe to battery +ve. Set ignitionswitch OFF.

Now touch the black probe to battery –ve, write down voltage (call this V).

Now touch the black probe to ammeter, both terminals should show V.

Now touch the black probe to lightswitch 2, should show V.

Now touch the black probe to lightswitch 10, should show V.

Now touch the black probe to ignitionswitch 12A, should show V.

Now touch the black probe to ignitionswitch 13, should show no volts. Turn ignitionswitch on, should show close to V (may be slightly less).

Now touch the black probe to coil –ve, should show the same as immediately above.

Somewhere in the above chain of tests you will lose the voltage. This will indicate a fault in the section between that point and the previous point.

My money is on an erroneous connection to one of the switches. Note that ignitionswitch 12A is NOT the same as 12.
Anyway, the above routine will identify the issue.
Note that none of the charging system wires need be connected for this procedure, and for simplicity it may be better that they weren’t (in case there is a fault with the reg/rec confusing matters, for instance).

At a pinch the above tests could be done using a small 12V bulb with wires attached, if a multimeter is not available, but the results will be less quantifiable.

Let us know how you get on!

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That's really helpful once again, thank you. I will probably have to wait till next weekend to try it, but I will try to make some time one evening before that to give it a go.

When the bike started it sounded good and started quite easily, so that was reassuring and encouraging.

Thank you again.

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Hello,

I did the checks as koan mentioned using a multimeter and all seemed to be ok. I am certain the wiring for the ignition system is correct, and after going over it I think I've got a good understanding of how it works now.my

However, it's still not running and won't spark. Why might this be?

I fiddled with the points for different reasons between getting it running the last time and I now think this might be my issue. I have noticed that the heel of the points that runs against the cam is not running against it for the entire rotation. When it gets to the flatter portion of the cam the heel does not touch/follow it. Is that right?

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