Backflow

Quingquad

New Member
Jan 13, 2010
123
6
23
Kentucky
I picked up a blaster a few months ago to restore. I got it running but bogs pretty bad when I hit the throttle. Did a litle bit of trouble shooting this afternoon and discovered back flow by putting a piece of plastic by the end of the pipe (silencer not attached, the platic was sucked into the pipe and then thrown out, back and forth, back and forth...)

Since these are two stroke engines and we're not dealing with valves that could be out of time, what can cause a backflow? Is this normal? Bad reed valves maybe? What other causes are possible?
 
completely normal as 2 stroke engines "scavenge" hot unburnt fuel from the pipe