When you say that the piston sticks out of the cylinder are you speaking about the top of the crown on the piston or the point at which the round bore diameter of the piston meets the crown of the piston? The owner said that the cases were split and they were machined then, so is it posible for the cases to be trenched for a 4mm crank? I will measure the stroke tonight and get a better idea. Since purchasing I have put a cool head on it, however have to started it at all. I have rotated the stator and nothing crashes. with 18cc domes what should the squish be?