Coil is very hot

[BigBiker]

Hello Glider, i`m new on this site and i have a strange problem on my `92 fatboy.
I`ve installed a couple of weeks ago a new horn and i have to remove the fueltanks because i don`t want to see the wires.
After all,i mount the fueltanks and everything is fixed now, but when i touched the spark coil,it was so hot i couldn`t put my hands on it.
The engine`s off and the ignition switch is on and only when i turn the switch a little bit back,i can hear a little noise in the coil.
When i push the engine`s stop-button, there`s no voltage on the coil also.
I have checked the wires to find out if there`s a connection or broken wire or whatever ,but everything seems to be okay.
I have really no idea how i can fix this problem.
After all,since i find out that the coil`s getting hot, there`s a detonation sound in my engine.
Could there be a possibility?
Glider, the last thing i want to say is thank you for your help.

Bigbiker

 

[glider]

Coils do operate hot once they have been energized for a while. Check the polarity of the coil to see if you have the hot wire on the + side of the coil.

Do you have a schematic for the bike?

If not there may help you out.

Wiring Diagrams Online - Harley Davidson Community

This schematic should be very similar to your bike.

 

[dangerdan]

I would also check coil resistance on primary and secondary of the coil.

Values should be within 5% - 10% as stated in the manual.

Also try this with the coil cold. Get a spray bottle with a fine mist and spray the coil while the bike is running. If you see any type of spark discharge or spark, its safe to say the coil is bad.

 

[BigBiker]

Dangerdan,thanks for your information.
I`ve checked the coil and the servicemanual says that the primary side have a range of 2,5 to 3.1 ohms and the secondary 11.250-13.750 ohms.
I`ve tested the coil in cold position and these are the next results:
primary 4 ohms secondary 11 ohms.
after that i tested the coil in warm/hot position ( it took +/- 12 minutes to reach that) by only the ignition switch on and the engine off,and these are the next results:

primary 5.25 ohms secondary 12.92 ohms.

Is that normal?

 

[dangerdan]

I`ve checked the coil and the servicemanual says that the primary side have a range of 2,5 to 3.1 ohms and the secondary 11.250-13.750 ohms.
I`ve tested the coil in cold position and these are the next results:
primary 4 ohms secondary 11 ohms.
after that i tested the coil in warm/hot position ( it took +/- 12 minutes to reach that) by only the ignition switch on and the engine off,and these are the next results:

primary 5.25 ohms secondary 12.92 ohms.:

The book says 2-3 ohms primary and 11k - 13k secondary .


Primary (5.5 ohms) is ok
Secondary should read 11k - 13k not 11-13 ohms. I think you meant to use a "COMA" not a "PERIOD"
If your getting 12.9k ohms on secondary you should be good, but if your only getting 13 ohms on the secondary, the coil needs replacing.

 

[BigBiker]

DangerDan, you`re right.
I`ve made the mistake with the ``Period,, instead of the ``Coma,,it`s definitely
13k ohms.
Thank you for your cooperation.

BigBiker