Ace, not trying to mislead, the point I was attempting to make was that even if the reeds were stuck somewhat open the engine would pop. The only way it could be a reed issue would be if they are stuck closed. I have not ever seen that happen. I'm still feeding to there being a large air leak. I would pull the intake assembly apart and take a close look at the gaskets. There should be visible signs of leakage on one of the gaskets. If it were weak spark the plugs would get wet. IMO there just is not enough crankcase velocity to get the charge up into the cylinders. An air leak or poor sealing rings are the only items I can thing of that would do this. Unless the needles are set way lean and the metering needle is stuck in the open position.