Sounds like the coils in the stator are heating up and cutting out. Either that or the SCR´s in the CDI module are going bad. Any way , your right its ignition. Spark plug coil primary should be less than an Ohm. Thats the two small wires, not the spark plug wires. I don´t recognize the model number of motorcycle. If it has a CDI module with the part number TIA10-20. I´ve got one.