Don't worry about it. Its probably a dykes ring which mainly seals against the cylinder during the combustion stroke-the combustion pressure pushes the ring against the cylinder creating seal. On the upstroke, there is less resistance (no combustion pressure) and less compression. Its a power saving feature that reduces engine friction. I've had supertiger engines that had virtually no compression and needed a little castor oil injected through the glow plug hold to seal the ring enough to draw fuel to start. The engine ran as powerful as other comparable sized engines in its class..go figure..