I have had a pressure test go well but o rings still leak when hot , usually protocall for me is pressure test, compression test, check pick up, plug cap ohm reading(never good), cable play carb sync , before I even kick someone elses bike. I had a bad experiance a few years back , a well known builder built this kids motor but he needed it tuned didnt do my usual machanical testing and I blew a hole in piston within 20ft from my driveway , turned out to be not enouph cas sealant behind crank just plain out missed 3 inches. Im sure piston was already going b4 it got to me