SM. ignition problems

[John Cliver]

1952. SM with electronic Ignition.........coil really warms up after running a while. wrong coil ?? Not using the porcelain resister . Any ideas ??

 

[rustred]

Using the 6 volt coil on a 12 volt system it will
Get hot. Get a 12 volt coil.

 

[used red MN]

Need more info about the coil you have on it. If it is the IH “bullet style” the majority of those are 6 volt. See link. IH bullet coil Measuring the ohms across the primary (the two small terminals) with it disconnected is the for sure way to tell what you have. Measuring 2.5 to under 4 (many 3) ohms LV primary resistance is a 12 volt coil, and 1+ to near 2 ohms for a 6 volt, many are 1.5 ohm. A coil under normal operation can get warm enough that you won’t want to put your hand on it.