So I had to take the water jacket cover of my newly acquired Merc 25 2 stroke (broke a bunch of bolts... different story.) and I noticed that it doesn't really have a cylinder head. This is kinda confusing for me as I've never seen a full sized engine without a cylinder head that's removable. So I guess you can't really blow a headgasket on one of these... Hmm, Just thought that was interesting. Pros- No more blowing head gaskets, Water intrusion into the cylinder due to leaky water jacket seals on HG. Cons- If you strip a spark plug hole, mess up combustion chamber somehow... You're screwed!