"Robert M. Gary" wrote in message
om...
If you get next to nothing on a mag during
runup, don't switch back to the good mag or you may blow out your
exhaust. Let the engine die or pull the power back to idle before you
switch back to a working mag.

That's how "youths" make cars backfire. Switch off the ignition then
turn it on again after a short while. Makes a big bang.

Paul