Prior to making any adjustments, just make sure that the rockers are both loose at TDC. If they are loose, valve lash doesn't enter into the compression issue as both valves are closed.

Put a few drops of fuel into the glow plug hole and then re-install the plug. Open the throttle full open and hand crank it a few times. My guess is that the compression is going to suddenly appear and all is well.

Mount the engine and fire it up. It isn't broken it yet, so it hasn't reach full compresson abaility yet. Chances are very good that there is nothing wrong with the engine. Most complaints about no comression of 4 strokes comes from handcranking them with the throttle shut down. If it can't get air through the carb, there is nothing to compress.

Try the little bit of fuel and open the carb and see what happens.

Don