Author Topic: What Are The Symptoms Of Coils Going Bad?  (Read 2083 times)

J6G1Z

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What Are The Symptoms Of Coils Going Bad?
« on: March 25, 2014, 07:38:21 am »
I have read a few posts on the Ascot Owners Group of VT Ascots having Coil problems. Could someone please explain to me the symptoms experienced when the Coils start to go bad?

My VT Ascot has a high speed miss or flat spot that I need to resolve. This bike has had the exhaust modified into a true dual exhaust system & has had the air-box modified to flow more air also. The exhaust header pipes have EGT bungs welded onto the header pipes approximately 3" from the exhaust port. This leads me to believe that the previous owner who modified the bike probably re-jetted it correctly & tuned it by monitoring the exhaust gas tempertures. I have not inspected the carbs to verify what jets are in the bike though. Unfortunately I do not know the bikes history & can only go off of observation.

I'm wondering if the Coils are starting to go bad. What happens when the Coils start to go, do they fire irregular or do they just plain fail completely? I have a parts bike that I have been thinking of swapping the Coils with, but that bike has about the same mileage on it (approx. 20K +/- miles).

Any advise will be greatly appreciated.

Thank you
J.


Whata

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Re: What Are The Symptoms Of Coils Going Bad?
« Reply #1 on: March 30, 2014, 12:05:46 pm »
I've read the symptoms are that the ignition starts to fail when the engine gets warm (and so the coils). It will probably start with irregular running and get worse untill there are too many bad sparks in a row and the engine dies.
I've had this problem and they didn't fail completely, always working ok when cold.

If you have a flat spot in top rpm, mixture would be more likely.. this engine seems very sensitive to mods in the flow path.

Gr Wouter

J6G1Z

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Re: What Are The Symptoms Of Coils Going Bad?
« Reply #2 on: April 12, 2014, 08:31:51 am »
I replaced my coils with a pair of "take off" coils from my parts bike. My parts bike has less miles on it & has sat unused for probably 5-6 years now. I also replaced my plugs for some fresh NGK plugs. My old plugs were really ugly when I removed them. No telling how long they have been in the bike. Between the two, the problem has gone away. I'm beginning to think that it may have just been a bad sparkplug problem. Sometimes it is just the basic stuff that requires attention.

If your bike is sputtering, or has a miss in its RPM range, try changing the plugs. It's not that difficult to access the plugs once you remove the fuel tank. The recessed plug in the rear cylinder is a bit tough to get to, but not real bad.

That is all for now.
J.