Bad coil?
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Intermediate
Joined: Dec 2011
Posts: 26
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From: St Louis, MO
Bad coil?
Ive got a 99 Fatboy with and Evo that wont start. Sparing the details, Ive had a few people tell me its probly a bad coil. Its got a Dynatech DC6-5 TwinFire II Single Fire coil installed.
To troubleshoot, I first checked the resistance in the primary and secondary circuits. Primary read fine, around 2.7 Ohms, but the secondary read really high, around 18,500 Ohms. According to the service manual, it should read between 10k and 12.5k. Is this higher resistance because it is an aftermarket coil and possibly normal??
Secondly, I decided to check the spark using a screwdriver between the plugwire and the plug, the spark is a pinkish orange color. If Im not mistaked, this means a weak spark, right?
With this info, should I conclude that the coil needs replaced???
To troubleshoot, I first checked the resistance in the primary and secondary circuits. Primary read fine, around 2.7 Ohms, but the secondary read really high, around 18,500 Ohms. According to the service manual, it should read between 10k and 12.5k. Is this higher resistance because it is an aftermarket coil and possibly normal??
Secondly, I decided to check the spark using a screwdriver between the plugwire and the plug, the spark is a pinkish orange color. If Im not mistaked, this means a weak spark, right?
With this info, should I conclude that the coil needs replaced???
Seasoned HDF Member
Joined: Aug 2007
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From: NW AR
I'll tell you it's a bad coil if it makes you feel better. That's not your problem, but if it makes you feel better, WTF.
You have spark. Do you have compression, fuel and timing? You're missing one of the three. Is this EFI?
You have spark. Do you have compression, fuel and timing? You're missing one of the three. Is this EFI?
Thread Starter
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Intermediate
Joined: Dec 2011
Posts: 26
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From: St Louis, MO
Dr Hess, I havent gotten any further than checking for spark... I was convinced it was the coil, so didnt check further.
Soft 02, yep... checked the wires also... they checked out ok.
Soft 02, yep... checked the wires also... they checked out ok.
Seasoned HDF Member
Joined: Mar 2007
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From: TOAK western branch
If its not a high comp engine than a weak spark should start it. Did it just stop working. Was there something you changed then it stopped working. Air, fuel, spark, and compression are the first things to check.
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Thread Starter
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Intermediate
Joined: Dec 2011
Posts: 26
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From: St Louis, MO
I had a hard time getting it started from the get go. I suspect some of it was getting use to the choke, but I also changed the plugs and it ran like a champ. Then sunday, I rode about 100 miles, ran great all day until I was just about home, then it sputtered and died... havent been able to start it since. I havent changed anything at all on it.
Well Im obviously gonna have to do some more troubleshooting in the areas you mentioned. Thanks for the info!
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From: Niles Canyon Ca.
Go to Dynatechs web site and download the instuctions & trouble shooting guide for that setup first thing just so you have it .
If the coil is making spark I'd be looking at the plug wires and some fresh plugs to start after making sure you have gas getting to the cylinders . About it could be unless you've lost all compression ........
From the sounds of it I'm suspecting you have intake leaks screwing up the fuel mixture badly if she's been a bitch starting since the gate or the timing is way off .
One last thing just as a dummy check , pull the fuel line off the carb with petcock closed and blow back into the tank by cracking it a bit with the right side gas cap off . This can blow off any sludge or build up that can block the filter screens on the petcock killing your fuel flow , also check to be sure the breather port on the gas cap isn't blocked too . This does happen some on older iron .
If the coil is making spark I'd be looking at the plug wires and some fresh plugs to start after making sure you have gas getting to the cylinders . About it could be unless you've lost all compression ........
From the sounds of it I'm suspecting you have intake leaks screwing up the fuel mixture badly if she's been a bitch starting since the gate or the timing is way off .
One last thing just as a dummy check , pull the fuel line off the carb with petcock closed and blow back into the tank by cracking it a bit with the right side gas cap off . This can blow off any sludge or build up that can block the filter screens on the petcock killing your fuel flow , also check to be sure the breather port on the gas cap isn't blocked too . This does happen some on older iron .
Last edited by TwiZted Biker; Dec 28, 2011 at 10:37 PM.
Seasoned HDF Member
Joined: Mar 2007
Posts: 66,948
Likes: 4,573
From: TOAK western branch
Go to Dynatechs web site and download the instuctions & trouble shooting guide for that setup first thing just so you have it .
If the coil is making spark I'd be looking at the plug wires and some fresh plugs to start after making sure you have gas getting to the cylinders . About it could be unless you've lost all compression ........
From the sounds of it I'm suspecting you have intake leaks screwing up the fuel mixture badly if she's been a bitch starting since the gate or the timing is way off .
If the coil is making spark I'd be looking at the plug wires and some fresh plugs to start after making sure you have gas getting to the cylinders . About it could be unless you've lost all compression ........
From the sounds of it I'm suspecting you have intake leaks screwing up the fuel mixture badly if she's been a bitch starting since the gate or the timing is way off .