I have a spark problem. Sometimes I get spark and sometimes I don't. I disconnected main wiring harness. Checked plugs, caps, ignition coils, wires - all within spec. I checked the stator coils and they are within spec. I bought a new CDI and it doesn't solve the problem. I have checked all grounds and seem to be good. No evidence of frayed wires etc. I am at the end of my rope. Any advice?