Motorcycle Repair: loss of spark to rear bank, rear cylinders, conductors

Question
1984 honda v40 magna 15k miles  hi, after running for 20 mins, hot. i lose spark to rear bank of cylinders, ive ohmed coil packs and even swapped them replaced cdi modules, cleaned ig switch, checked all connections, still lose spark to only rear cylinders, tach also goes dead i unplugged incase it was shorted, no change. can u help ?  

Answer
Hi Tom,

With respect to all of the tests you've performed, I suspect an intermitent problem with the ignitors, or conductors in the circuit.

Visit the following website to learn more about testing the ignitors:

http://users.rcn.com/kochc/moto/spark/ig_repair.html

Respectfully,
Mark Shively