Blown Ignition Coils

[ddeblois1206]

Greetings all,

I have blown 2 ignition coils on my 1948 Chief in the past few months.
The bike is still a 6 volt system.
I have been using 'Napa Mileage Plus IC7SB' for the replacement coils.

Anyone have any idea why I keep blowing coils?
Is this the correct replacement coil?
Is there a different replacement coil that will work better?
Could it be something with my charging system (to high output)?

Any thoughts would be appreciated!

Dave in Kentucky - 15039

[RicD]

Sounds to me like you are over charging the system. I would contact Indian Frank about this problem he is the generater guru.

[20scout]

I'm not familiar with that coil, does it have a built in resistor or not? My coil say NO EXTERNAL RESISTOR on them. Try a different coil and see what happens.

[Tom Lovejoy]

I would try hooking up a metter and see what it's charging at, an anolog metter works better than digital - don't know why. Don't have a Cheif, but on my Scout you can just swing the shoe one way or the other. See what it's doing, usually on the machines I have seen. If over charging, you will boil over the bat - or even run it dry. I would see how many amp's its putting out, at idle and with rev's. Just my 2 cents good luck.

[Bill Huth]

Hi Dave,

I copied this info down from when Stan Jessup had modern p/n's for Indians listed on his website. I don't think he lists this stuff any more.
Coil 6 Volt (internal resistor) GC88 Sorensen
Coil 12 Volt (internal resistor) UF-3 Standard
Coil 12 Volt (internal risistor) IC14SB Napa
It's desc/PN/Brand
I can't vouch for it, I just copied it for future reference.

Regards,

Bill

[ddeblois1206]

Thanks for the help

Thanks for all teh suggestions. I checked the generator output and it was right on. Still, I backed of the 3rd brush a little to lower the output even more (as winter rolls around there will be less and less night time riding).
I also changed to an Echlin coil. Supposedly a step up from what I have been using. We'll see.
Also, while looking for a Sorensen Coil I found this cross reference guild form the Oregon Trail Chapter: http://www.amcaotc.org/indianparts.htm

Thanks again -
Dave

[redfred84]

Hey Dave,
Leaving the key on, while the bike is not running may have leathel results to your coil (if the points don't erupt first). Are you sure that you are turning OFF the ignition when you stop to buy that girl a drink?

Packing extra coils, for when I forget to turn them off whilst buying girls drinks, RF.

[Lonnie]

Speaking from automotive experience with 12-volt GM systems, if you leave the ignition on and the points are closed the coil could end up overheating and be ruined. I've not seen one literally explode but I have seen the points actually welded together in the process. After that happened a time or two I ended up being more careful.