Nine times out of ten an engine problem is actually a fuel tank/line setup problem. Double check the tank to make sure everything is installed properly and in good condition. Check fuel lines for cracks/pinholes.

Then again, a bad tank setup will not make the engine loose compression. Are these engines really loosing compression that quickly? I've only heard of instantaneous compression loss with four strokes. Really the only way with two strokes is to have the backplate or head come loose.