Sounds exactly like what mine was doing. I also had what appeared to be a good spark, then it just stopped producing any spark. I suggest a new coil, worked for mine. Hope this helps.First time Huztl 660 builder here looking for help. I completed my build this morning and tried to get her started. Got nothing, it won't even pop with the choke on. Pulled the air filter and she is getting fuel. Pulled plug and have good spark. Pulled flywheel and woodruff key is good. Gapped the ignition coil and flywheel per the service manual specs. The kit carb is adjusted 1 full turn out from seated each for HI and LO. It passed pressure and vac tests during the build. I even tried starting it in fast idle mode (which I don't have, had to use zip tie to hold throttle open. Looks like OEM trigger assembly in my future.) Pulled so many times in fast idle flooded her out to the point fuel was leaking out of the muffler. Any ideas?