Moki tunning help
Make sure you are using large fuel line from the clunk to the carb for starters and go over evry bolt on the motor and tighten them up. My 1.80 did not respond to high end needle settings till I swithched to large fuel line and it took care of the crackling. Another thing to try is add another washer to your glow plug, if this helps order another metal gasket for the head and install it then take the extra washer back off of the glow plug.