Depends on how you raced the engine... Check piston sleeve if the piston is able to overshoot the piston liner / sleeve. If you can do this with the piston sleeve out the crankcase with just your bare hands, then it's already time to retire it.

Secondly, to check compression, what people do is to crank the engine flywheel until the piston closes the exhaust port. Put a few drops of after run oil into the exhaust port of the crankcase so that the oil is trapped there at the exhaust port where the piston is blocking.

Then, try to crank the flywheel up to TDC slowly while observing if there are any bubbles coming out of the exhaust port because of the after run oil. If there are a lot of bubbles all the way when you crank up to TDC, then the piston sleeve has loss compression and does not have the required seal anymore. Of course, do this with the engine head and plug mounted.