I bought the ski like this. I stripped the entire ski but left the crankcase, cylinders, head and manifolds in place in the hull. I had it painted and decided to take the head( a twist billet head BTW) off and look at the cylinders. This is what I found. The front cylinder is very clean, very little carbon. The back cylinder is as the picture shows. The cylinder walls look perfect. The dome in the head above this piston has a small chip in the o-ring area outside the combustion chamber. I am sure that detonation is the cause of the dent and that this engine was close to having a very expensive repair bill. I just finished rebuilding the carbs. I can't remember what the compression was before I took it all apart. I did not write it down but I remember thinking it was high enough that it needed race gas and not just straight 93.(Previous owner ran 93 in it) Good thing is I found out about it now while it is a relatively cheap repair job.