i just got this 8n and the previous owner couldnt figure this carb problem either. he rebuilt the carb including the carb dip cleaning. it will only run with the main jet removed.....or the choke pulled. i looked at it and thought it was a simple plugged passage. i removed the bowl and found a bit of soft rusty mush in the bottom (there is the problem..."im so smart") cleaned it and put it back on. still not fixed... took off the carb and took it apart and cleaned all the passages in the top half and recleaned the bottom half (i must have missed something "hard to believe since im so smart...") put it back together and put it on.... still the same... checked fuel flow and it was good. looked in the manual found the screen at the carb.checked it and cleaned it (that has to be it it looked a little plugged) put it back in....still not right ("maybe im not so smart")
the needle looks corroded so today im going for a complete kit and try again.
so here i am...humbled....asking for ideas ( when you dont know...ask)