[WilliamWonka17]

So a little while ago my buddy was riding his 400ex when he noticed there was some smoke coming from his handlebar area. Turns out his wiring harness completely melted and had to be replaced. So far hes replaced the coil and checked all connections. What are some other things it could be. The old wiring harness was fairly mangled so it is possible that could have caused the failure.

 

[Here 2 help]

Well,the ignition system is separate from the starting and lighting system - ignition is AC and the rest is DC - you kill the spark by grounding the CDI box - so a no spark issue usually comes down to a connection problem both on the wiring side and the grounding side. You can lose spark simply by not grounding the engine correctly or by accidentally grounding the kill wire.

 

[farmerjo1206]

so this is really funny cause this happend to my 400 and i took all the plastics and fuel tank off pulled the boot and put a new spark plug in and still nothing. so i just started wiggling wires and tried it and it work and still works.