Have seen some GY6's that produce over 100 psi on the compression gauge, but when performing a leak down test, the cylinder cannot even hold enough pressure to even get a reading. My guess is that if a leak down test were performed, you would find leakage around the valves. Common sense would lead one to believe that bad valve(s) would lead to a failed compression test, but we see this all the time at our shop (despite the acceptable compression readings).

Also, you stated that it was well used. It may be worthwhile to confirm the previous owner has not tampered with the timing or that the timing has not jumped out of spec.

 

Success! I put in the new stator and it took right off. Thanks to all that helped. It runs good. Now to find out what else is wrong with it.
Tom