ORIGINAL: aspeed
Maybe the headspace is too big. It may need a shim removed if the screw is tightened down all the way and still isn't down far enough. I assume you know more about the dangers of running overcompressed than I do.
Whoa! Back it up a bit here - if the head space is too big then you would get a misfire big time due to the compression being way too low and if the comp is too low AND the ether content is too low then how did you even get it to start in the first place? Couldn't have been fun.
Something smells very fishy here and it ain't ether.
Check for head leaks as mentioned and get the thing to go minus the muffler firstly.
Good luck.