well if it sounds like it's coming from your glow plug.. and you can see the piston sleeve move up on it... your head on your engine is loose I bet... make sure you line up the sleeve right on the piston.. and make sure you put some BLUE loctite on the screws of the head and screw it down, DON"T STRIP THE SCREWS though... make sure it's tight.. I think that's where your loosing compression.. I had that happen on my Hyper 21.. It needs to make the Pop pop noise... no hissing noise.. pop pop pop..... and if you want to see if you got good compression.. hold a finger over the carb... and pull the starter cord... sucks your finger pretty hard.. your good.. it doesn't suck on your finger.. you got a rebuild coming up..