Magneto Kill Switch Wire Shorted to Ground

[bertsmobile1]

The kill wire is a GROUND wire
Ground = off
open = on
A spark when the wire is connected to the block with no plug but no spark with a plug = weak magneto or bad connection between plug cap & HT wire

 

[StarTech]

And don't forget a bad plug. Even plugs the shows spark outside the compression zone can be failing under compression load.