if you were to open the throttle, is it easier to blow into? does it prime then?
i would guess it is a blockage in the carb. but with the tank empy, unhook fuel line going to the engine, can you blow through pressure line then and get airflow out the fuel line that goes to the engine?
if so it...
what does the manual say for returning back to factory? I'm guessing it gives a count of turns for the high speed, is that one of those ones that you have to hold the carb shut while you close the LSN then back off from there?
if so make sure set the idle gap to 1mm, about the with of a standard...
first option would be to maybe try removing the plug, put a few drops of fuel into the top of the engine, replace plug, then try firing.
or for figuring out issues with priming, i will disconnect the pressure line from the exhaust and blow softly into the line which will prime the engine with...