I have a 1995 Kawasaki 750 STS jetski. The problem was when I bought it, that it ran for about 5 minutes, then would lose power, and eventually would not restart at all. After pulling the engine apart, I found 1 burned out piston. We put 2 new pistons in. The problem was still the same. We then found that the relief valve was broken (you could blow through it both ways). It seemed that maybe there was a vapor lock being created. We replaced that valve, but still the same problem. It seems that the magneto box is overheating. Not sure if this jetski is supposed to shut down when it overheats as a safety precaution or not. The main question is, what needs to be done to stop the overheating.