My Dads Two Speed had 50 psi left and 70 psi right, I didn’t even bother checking with oil as obviously theres a problem. On barrel removal the rings had broken and also had a large gap (or bits missing). My 600 engine which has slightly worn bores but not enough to warrant reboring has compression over 100 psi and most importantly both cylinders are to within a few psi. When I did the honing and fitted new rings I removed the original Scott ring end stops and fitted taper pins and ground the rings to suit the pins, if I remember right it was three thou per inch of bore for the ring gap. Comparing the before mod and after mod ring gap it was surprising how much difference there was. Kev
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