In the 1960s two stroke tuners would 'stuff' crankcases with material to increase the compression ratio. Flywheel holes were filled, etc. However, modern crankcase reed motors don't need an increase in compression. They need flow and if anything extra volume of fuel/oil. In the 1990/2000s Honda RS125/250 tuning included matching the barrel to the cases, smoothing out the bottom end for flow and trying to fit later (bigger volume) reed cages. Looks like your engine was 'tuned' like that.