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Old 05-12-2015, 07:02 PM   #1
rooster
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Default Checking your coil?

Is there a way to check/test a coil?
79FLH runs fine until heat build up and then sputters and misses terribly. Sit for 30 min runs fine, repeats...


I installed a new Andrews coil but have not test road yet. I"m just curious if there is a way to check?
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Old 05-12-2015, 07:08 PM   #2
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Default Re: Checking your coil?

I usually end up checking exactly like you are gonna...change and run it...There are ways. but, The Change and run , method is Easy, Fast, and Usually Final.
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Old 05-13-2015, 02:06 AM   #3
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Default Re: Checking your coil?

I don't remember where I got this maybe on here maybe the HAMB. but I kept this info in my files.

"cross the coil leads with a multimeter set on ohms and the lowest setting usually 200
if it reads .5 to 1.5 its prob a good electronic ign coil
if it reads 3.5-6 its prob a good points coil
if it zeros out its bad"
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Old 05-13-2015, 11:46 AM   #4
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Default Re: Checking your coil?

Take one of those sparking plug wire tools and place on the plug wire .If it is weak stick the tester directly in the coil. If it gets stronger you have faulty wires . Those testers don't work in magnetos [well] . They used to be made in USA by Bonney but now all you can get are imports. But it is still a good troubleshooting tool.
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Old 05-13-2015, 01:49 PM   #5
FredoTwoWheels
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Default

Heat up the coil with a blow drier and see if you get the same symptoms while the bike is still cold
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Old 05-16-2015, 09:19 PM   #6
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Default Re: Checking your coil?

New Andrews coil, new points and condenser, new volt reg, new plugs, checked mani for leaks and it runs worse now!
I have checked the points gap and timing, someone tell me what I'm doing wrong!
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Old 05-16-2015, 11:08 PM   #7
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Default Re: Checking your coil?

Have you inspected the advance unit?
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Old 05-17-2015, 06:26 AM   #8
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Default Re: Checking your coil?

Only from the outside to see if the springs are still there!
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Old 05-17-2015, 08:52 AM   #9
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Default Re: Checking your coil?

I had the same with my ironhead. The coil had one really fine crack in it, very hard to see. Take a closer look at your coil, with a magnifying glas if you can.
If you see no cracks you can rule that one out...
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Old 05-17-2015, 09:15 AM   #10
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Default Re: Checking your coil?

Most of the things to check have already been mentioned. But here are a few more. Check the wiring to the coil isn't backwards. Replace your condenser with the original, if it ran fine before. Then the coil, back to your original, also only if it ran OK before. If your originals were bad, you need to try known good parts. That doesn't mean new in the box it means parts off a good running bike. Call your friends with the same points ignition, their flavor beer will be in order.
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Old 05-17-2015, 10:30 AM   #11
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Default Re: Checking your coil?

Well I did find something this morning. The new Vreg i just bought is for a electron ignition, I'm running point. Unfortunately I discovered that after installing and running the engine.
1. I hope I didn't hurt anything!
2. Always check electrical parts before leaving the store! No matter how good the shop is.
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Old 05-17-2015, 10:44 AM   #12
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Default Re: Checking your coil?

Two things.....
1. I had a bad circuit breaker once that was weak.... when it got hot the contact would trip and kill power. Once it cooled it made contact again and would run. I changed it and it was all good.

2. Are you sure its not a fuel problem? Hot gas i.e. fuel line ran between cylinders can cause running problems. Also a stuck float making it starve? And last poor venting of the gas tank

Just a few things to check
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Old 05-17-2015, 02:54 PM   #13
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Default Re: Checking your coil?

Battery health checked?
A crap battery can cause all kinds og similar symptoms

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Old 05-17-2015, 03:35 PM   #14
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Default Re: Checking your coil?

It was about 80* coming home from Fuel Cleveland when it first happened but the next time it did it was about 65* so I don't think it is gas, but who knows! I'll keep chasing demons...
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Old 05-18-2015, 07:23 PM   #15
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Default Re: Checking your coil?

I have now replaced, coil, plugs, points, cond, volt reg and the slide in my CV carb.
Set the static timing and the missing persists. Could rod adjustment cause a misfire? What if the timing was off just a little?
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Old 05-18-2015, 08:49 PM   #16
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Default Re: Checking your coil?

Stator. Check to see what the battery voltage is when it sputters. Carry a volt meter.

I've had to mount one to the bars and run longer leads to the battery and take them out.

The ign coil ain't the only coil. If it's above 12.6 when its sputtering it's not a source voltage issue. Next would be after the Circuit breaker and another ride. Then so on to the ign switch and then positive of the coil primary circuit.

Once that's eliminated, get another condenser and ride on. A good one, not the cheap ass generic condensers that come in the kits.


Is it popping out of the carb?
Will it do it idling on the side stand too? (Keep a fan on the motor)
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Last edited by JAWS; 05-18-2015 at 08:58 PM.
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Old 05-19-2015, 07:35 AM   #17
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Default Re: Checking your coil?

Did you change or add anything to the bike before this problem occurred?
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Old 05-19-2015, 09:51 AM   #18
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Default Re: Checking your coil?

Battery !
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Old 05-19-2015, 10:06 AM   #19
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Default Re: Checking your coil?

the condenser could be grounding out,or,if you think there is a crack in the coil,sometimes you can run the engine in the dark and see slight sparks coming from the coil
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Old 05-19-2015, 11:48 AM   #20
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Default Re: Checking your coil?

sounds like fuel too me.....
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