Gday fellas. I was working on my 1983 s2 bevel yesterday, when I turned the ignition switch from on to off, a puff of smoke and a hiss came out of my right carby. The engine was not running I was just testing the indicators. Seems like the spark plug fired at the point of turning the switch off. Anyone had a similar experience? Is there a problem somewhere in the electrical system?
Don't worry it's quite normal. The coils are supplied with 12V and the spark is produced by the ignition modules breaking the circuit at the correctl time. When you switched the ignition off the magnetic field in the coils collapsed creating a spark. There co-incidentally happened to be some fuel vapour in one of the cylinders which ignited. If you pull a plug out you'll see that it sparks every time the ignition is switched off.
