I remember my Dad telling of an unforgettable experience he new of back in the late 1920s, of how a friend of his was going to loan a outboard to another friend to go fishing, but before loaning it to him, gave it a run in a tank to make sure it was running ok. Unfortunately he over revved it and the flywheel disintegrated, hitting him in the chest, killing him instantly…….needless to say Dad was always reminding me of the accident when he heard me revving my motors!