I bought a columbia moped from my local junkyard, it has a sachs engine on it, heres my dilema...it has spark, so i've tried putting a little starting fluid in the head, put the spark plug back on, and pedaled like hell....nothing. This is my usual routine check to see if there is spark on a moped, and usually, if it does, and i spray a little starting fluid in there, it pops and sputters for a second or two, BAM! its a runner! but this one doesnt, it just keeps turning over, like theres no spark. I know it has spark though, i put a new plug in it, and grounded the plug on the outside of the head, and pedaled like hell, and there was a spark consistantly jumping. then when i would put starting fluid in the head, screwed the plug back in, and pedaled, nothing happened, no popping or sputtering, nothing. i tried takin the carb off and the muffler off, in case either of the two were clogged and blocking flowage. Still no dice. damn. Any suggestions?