On my buddies Eveloution 58 the noise was because either the spark plug cap was not on tight or the spark plug was loose. Not sure but I belive all electronic ignitions when turned on release a charge and that may be what you are hearing. As soon as we hear the sound of the electrical charge on his 58 we check the spark plug and cap. Hasn't happened since. Never had it happen on my DL50,

Jim