Before undertaking any maintenance you must ensure your engine is safe it could cause significant injuries if it was started by mistake while you were working on it.

Primarily this is to prevent the engine being started and the propeller spinning while you are working on the engine.

Do not rely purely on your kill switch, you can see from below a common wiring diagram for the kill switch.

The kill switch is item 3 and is shown in the open position which is how it sits when the clip is fitted i.e.The engine will fire

The test tells us that with the engine in a condition where it won’t fire (clip removed or stop button pushed) there is continuity across the switch and for the ignition to be in a condition where it will fire (clip installed) there needs to be no continuity across the kill switch.

If either the black or white wire are broken or disconnected the engine will be in a condition where it is as if there is no continuity across the kill switch and the engine is in a condition where it will fire, not likely to happen but possible.

If the wire is going to be broken, it’s most likely to happen while you’re working on the engine and of course the wires are most likely to be disconnected while you are servicing the engine.

So….  Before you start any work on your engine, ensure the kill switch clip is removed (If you have a kill switch)  and pull the spark plug cap(s) and then you know that no matter what, your engine will not fire and you will be working on a safe engine.