Motorcycle Repair: 1983 vf750f, plug caps, resistance value

Question
Idles fine, but cyls 1&3 and tach cut out above 2000 rpm. I have replaced the 1-3 spark unit, the coil, the pulse generator and even  disconnected the 1-3 spark unit signal wire at the tach, but the miss does not clear-up. Bike ran fine for a year. Idled in the rain and then developed this problem.

Answer
Phil,  check this site for possible help:
http://users.rcn.com/kochc/moto/spark/ig_repair.html

Did you check/change the spark plug caps? What is their resistance value. Should be around 5k ohms. If they are originals, they may be arcing through the caps to ground.
Check all the wiring connectors that relate to that set of cylinder electrics, including grounds.

Did you try swapping the spark module connectors to see if the problem shifted to the other pair?  

The above page has some good ideas about how to properly troubleshoot the problem.

Bill Silver