Thanks for reply. The Holts aerosol specifically says that it contains lubricant so is suitable for 2 stroke engines. I wouldn't know whether they are spinning a yarn or not on this, but I did only run it for fifteen seconds with the engine start.
Saying that there was so much petrol lub mix which had filled the cylinder and that I had drained out, I am hoping that alone would be enough to lubricate cylinder rings.
I only know about the valve inside the primer bulb. My guess is that either you run the engine till the carb is dry, or swap the fuel hoses on the primer bulb so as to pump the petrol in the carb float chamber back into the tank, should you wish to purge the carb of fuel.
My guess is that you are suggesting that the primer bulb will have been pressed too many times causing excess into the carb. There is an overflow on the carb and it appears excess fuel is suppose to vacate the carb and return to the fuel tank. However as this is not happening, perhaps the valve in the primer bulb is allowing fuel to siphon through the carb and into the cylinder.
Gutted that 100psi will not be enough. A couple of videos are telling viewers that something over 90psi for a hedge trimmer will still mean the engine will run. I'll do the compression test again, reason is I see you have to have the throttle open when you attempt this. I probably had the carb on choke when I pulled it.
I agree that most of the compression tests for similar engines are over 110 psi with many reaching 120psi.
I just found this video which makes me chuckle the number of saws he drags out the back of his pickup.
Lastly there is a video explaining that a dirty piston can cause problems, so I might take off the cylinder and look at the piston. Just hope I can make a gasket if the engine is worth saving.