I think I have the same problem. I havent replaced the switch but the engine turns with no spark. Simple test was to detach the kill lead on the magneto. It starts perfectly. This says the magneto is being earthed. Checking the wiring diagram it seems there are two causes. One is the ignition switch itself, but if you have replaced it then it is unlikely to be that! So the other one that grounds the blue lead is pin 2, the blue lead from the PCB box. Has that blown? If that blue lead is held to earth, then the pcb box has a fault. Either cut it! (in which case the other cut-outs wont work) or check the box for fault.
hoe that helps
kevin, April 2011
