In what I have found, using a compression tester, the guage reading is just a reference. It is a static reading that can change with temperature, altitude, hot or cold. Seeing different reading is not abnormal. There is no way to get a dynamic compression reading with the saw running 12000 rpm. What I have found is that when you have alot of cranking compression, the biggest thing to watch for is the tuning of the saw. Here is a example. Lets take your said saw, run and tune it to four stroke but clear up when cutting wood. Back to four stroking out of the wood. Everything sounds good, you can video it and share, everything seems great. But take the same saw out and really work it, non stop cutting, as the motor gets to operating temperature, you will have to richenup the high side a considerable amount. Finish up and let the saw sit over night. Next day the saw will be so rich it went turn 10k. So inevitable you have a saw where you constantly have to tune carburetor. Hope this helps.
