Need a good coil test

Trying to eliminate most everything that would cause a miss that occurs going down the road. The miss has caused the bike to completely shut off but then come back to life while I'm still rolling. On another post, htown suggested that it could be the ignition switch which it doesn't seem to be but to be sure, I'd need to replace it. Before I do that, I want to check the coils. One is a newer Emgo that I was talked into buying and the other is older (no name). I don't know which one I trust less. htown sent me a link with the following test:

With this same piece of wire, you can test your coils and plugs. Simply disconnect the black wire from the box to the coils at (3), and then, with one end of the wire connected to the battery at (1), touch the other end to the (-) negative coil terminal (3). When you break this connection, you should see a spark at the plugs if your coils are good. If this does not produce a spark, check the coil wiring and (what else?) the connections, all the way from ground to point (3). If all connections are OK then you probably have a bad or open coil.

Problem is when it says, "with one end of the wire connected to the battery..." I'm not sure if they are referring to a separate wire or what. Also, I'm not sure if all other connections should be off the coils when this test takes place or not?

I have checked all connections and for bare wire shorts or anything obvious.

Also, my gel cell battery was reading 13.2 volts but now off the charger only 3 days in a 30 to 40 degree garage, the battery now puts out 11.2 volts.

If anyone has a coil test or can clarify this, I would greatly appreciate it. Jim

The coil test would be more of a go - no go test and not sure how good it would be at detecting an intermittent miss. Best way would be substitution of a good coil.

For the ignition switch, you could eliminate that as a problem by just disconnecting and jumpering all the wires together and then try it. (Write down or take a picture of which wires go where on the switch first.)

I think 11.2 volts would be too low. You may have a dead cell in the battery or else something is discharging it very slowly.

Russ

If your battery goes from 13.2 volts to 11.2 volts in 3 days, with nothing connected to it, it's done, and it's time to replace it.

Ken

lcrken said:

If your battery goes from 13.2 volts to 11.2 volts in 3 days, with nothing connected to it, it's done, and it's time to replace it.

Ken

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The battery was in the bike and hooked up but the key was off. I have a Harbor Freight battery load tester but not sure if gel cells need to be treated differently.

Charge battery check the voltage then leave it disconnected from bike and check voltage again after few days if its dropped its no good if its same then fault is in bikes wiring causing it to drain. if the ignition switch is the cause of cutting out it may also be cause of drain on battery or it maybe battery causing cutting out if its failing. It could be something else but you will have to try one thing at a time. does it have points fitted if it has electronic ignition these can have bad connections on pick up coils and some are affected by low voltage

toppy said:

Charge battery check the voltage then leave it disconnected from bike and check voltage again after few days if its dropped its no good if its same then fault is in bikes wiring causing it to drain. if the ignition switch is the cause of cutting out it may also be cause of drain on battery or it maybe battery causing cutting out if its failing. It could be something else but you will have to try one thing at a time. does it have points fitted if it has electronic ignition these can have bad connections on pick up coils and some are affected by low voltage

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It's an older Boyer. I checked all the connections and everything looked good. I've got the battery on charge now so after it charges, I'll disconnect it from the bike as you suggest and see what I get. Thanks, Jim

Boyers need a strong ground. Clean and refit to frame. Battery replace. Coils work or don't. Clean up fuse contacts too.

If you take apart the ignition switch you'd be amazed at all the crap it has accumulated over the years causing a lot of the electrical problems you are experiencing.
I know mine did anyway. Mine kinda looked like a fuzzy, sandy mess.

Torontonian said:

Coils work or don't.

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Not always true. They can fail when hot but work ok the rest of the time. I had a set of PVL 6v coils on my 850 that were apparently bad right out of the box. They worked most of the time though. But when hot bike idled poorly, stalled easily and was hard to restart. Symptoms got worse as time went on. Drove me nuts trying to figure out what was wrong. Finally I binned them, put in a CNW coil kit, all good now.

The OP's symptoms remind me of when the Lucas ignition switch started going bad on my 750. It would cut out while I was riding, I could wiggle the key and it would come back to life. I replaced it with an EMGO replica switch that has been working perfectly for 8 years now. There was an article published in the INOA newsletter a few years ago about how to take the Lucas switch apart and rebuild it. One of these days I'll try that with mine. On the 850 I'm just running a toggle switch...

Torontonian said:

Boyers need a strong ground. Clean and refit to frame. Battery replace. Coils work or don't. Clean up fuse contacts too.

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Some Boyers also need a minimum of 12 volts or they won't fire....The POS Boyer MK 111 Digital that I recently replaced with a Tri-Spark was one of them. I'll never own another Boyer product of any kind.

You can load test the battery by charging it up and then leaving the headlight on for two minutes. If it starts out at say 12.5 volts and drops below 12 it probably is not supplying the Boyer enough juice.
The best test of the Boyer function is to take the blk/wh wire and blk/yl wires loose from the stator plate. Pull the plug leads and stick some spare plugs in them and lay them on the heads. With the ignition on touch the wires together and you should see sparks at each of the plugs. If you get this it suggests that the boyer box, coils and plug leads are working in a static state.
Its possible the coils are mis=functioning when hot, but probably more likely the Boyer is not receiving full 12 volts at all times.
Could be due to weak battery or intermittent short in ignition switch, kill switch ect.
If it starts to die while running try wiggling the ignition key. I've had this happen more than once.

Regarding the battery drained in a few days, check the 2MC capacitor ( big blue box close to the battery) , even when ignition is swiched off the 2MC is still powered. and 40 years old capacitors leaks quite often, it's not a plain short circuit but just a few millamps.