No spark - new coils - old CDI

Patmanbbe

Been Around the Block
Greetings guys, Yea I know its me again...

I just finished wiring up my bike's ignition and charging system. I havent wired up the guages or lights yet but those are on a seperate circuit anyway.

I get the starter to crank when I push the start switch and I also verified power to the coils. However when I grab a plug and hold it to the frame to check for spark I get nothing. Not even a flicker.

I have brand new Dyna 3.0 Ohm mini coils so I dont think they are the issue. However Does anyone know a good way to test these coils and verify they are good? I have a multimeter but I am not certain what to check for.

I am also using a CDI I bought on eBay. Is there a good way to test the CDI?

Any help would be awesome! Thanks guys!
 

Sonreir

Oregon
DTT SUPPORTER
Do they look like this? With a single spade connector on the coil?
 

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Patmanbbe

Been Around the Block
Sonreir said:
Do they look like this? With a single spade connector on the coil?

They look like exactly like that but they have two spade connectors on the coil.
 

Patmanbbe

Been Around the Block
It has output for two plug wires on one end and then two spade connectors on the opposite end. On of the spade connectors has a red dot next to it.
 

Sonreir

Oregon
DTT SUPPORTER
OK. Good deal.

You can follow these instructions for bench testing those coils:

http://www.dotheton.com/forum/index.php?topic=44556.msg679448#msg679448
 

Patmanbbe

Been Around the Block
Excellent, Thanks! I found in my service manual how to test the pick up coils too. Hopefully I can eliminate all the testable items and isolate the problem. I will post up my results when I have them. Thanks again!
 

Patmanbbe

Been Around the Block
Sonreir said:
OK. Good deal.

You can follow these instructions for bench testing those coils:

http://www.dotheton.com/forum/index.php?topic=44556.msg679448#msg679448

I did the bench test but I am not sure about the results. When I tested the coil I did get spark but not at the spark plug. I got the spark at the negative terminal on the coil. It was very nice bright blue spark. Is this what I should expect?

I also tested the pick ups and I get a good resistance rating from both signal wires on the pick up coil.

If I did the bench test on the ignition coil correctly I think I can safely say that my CDI is the problem. Any thoughts?
 

Sonreir

Oregon
DTT SUPPORTER
You shouldn't really be getting a spark at the coils' connectors. Did you have the clips secure?
 

Patmanbbe

Been Around the Block
I did not have clips. The connector on the coil is a tab with a pin hole in it. I feed the wires through the hole and wrapped tightly against the connector tab.

I guess to be more accurate the spark is happening on the wire that is connected to the negative tab on the coil as I pull it off the negative terminal on the battery. It is not happening at the spark plug.

I see the spark on the wire as I remove it from the battery negative terminal.
 

Sonreir

Oregon
DTT SUPPORTER
What you're seeing is the flyback usually absorbed by the condensor (in a points system). You should still be seeing a spark on the spark plug, though (assuming you have a wire running from the threaded portion of the plug to the negative terminal on your battery).
 

Patmanbbe

Been Around the Block
Yea I do have a wire run from the threads of the plug to the negative terminal on my battery. But I dont see a spark at the plugs.

I get about 13 Ohms resistance through the spark plug cable.

The battery is a bit low at 11.75 Volts. Could it be low battery voltage?
 

Patmanbbe

Been Around the Block
Ok I did a retest with the battery voltage at 12.6 and same result. No spark at the plug but I have spark at the battery terminal when I pull the wire off.

I have a wire from the threads of the spark plug to the negative terminal. The Spark plug is plugged into a good working plug cable then to the coil. On the positive connector on the coil I have a wire going to the positive battery terminal. On the negative connector on the coil I have a wire attached that I hold onto the negative terminal of the battery. When I pull this wire off I get a strong white spark at the battery terminal right as I remove the connection.

It seems the coils both might be bad. Any ideas Sonrier for an alternative test? Can I measure resistance through the coil?
 

Sonreir

Oregon
DTT SUPPORTER
Yes, you can.

Resistance through the positive and negative terminals should be about three Ohms. Resistance through the spark plug wires and the negative terminal should be around 20,000 Ohms.
 

Patmanbbe

Been Around the Block
Yea I just saw this video and did this same test.

http://www.youtube.com/watch?v=rRQ45lT2d3c

It looks like my brand new Dyna coils are both bad. I tested both and got a big fat nothing reading from the secondary winding test.
 

Patmanbbe

Been Around the Block
Well a quick update. It looks like the coils are good. I guess they are meant to be tested in a different way than was described above. It looks like these coils you test the positive to negative resistance and then you also test the spark plug terminals against each other. The primary coils resistance is within spec at 3.0 Ohms and the secondary is within spec at about 10k Ohms.

I am back to the CDI as the source of the problem. I know its a long shot but.... Does anyone have a good working CDI for an '84-'85 Yamaha fj600 that they could lend me for testing?

I also checked the pick up coils and while I don't remember the resistance I think it was ok. I can check it again.

Thanks guys!
 

Patmanbbe

Been Around the Block
Well I bought a new CDI and it should be here by Thursday. I plan to throw it on the bike over the weekend and see where I am at that point.
 

Patmanbbe

Been Around the Block
Not much progress made. I got the new CDI and I am having the same exact results. I am going to step back from the electrical for now and work on the suspension and wheels for now. A fresh look at it before I set it on fire will do it all some good.
 

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