I had just port matched and cleaned casting blemishes in my 66/80cc. Now wont idle and has low power. Revs well under no load. Seemd to be no vacume leak. Used all new gaskets. Has dilliato carb and boost bottle,new champion plug.
Soap is for cleaning spray any areas in all areas with gumoit ou as soon as it boggs or dies that's your leak 100% fool proof..
Then inspect that conrction or gasket ETC.