when I get this I know it's the middle range jet circuit. If you have seen the circuit you would understand. it goes through the jet and comes out in front of the filter or opening of the carb. the vent hole is about .030 real small. My advice is to remove the carb bowl, take this jet out and take some carb cleaner in a can or brake cleaner and squirt up into the opening for the jet and when you see a small stream come out the carb at the filter area you know you got it cleaned out, remove the filter of course. mine generally has a bunch of brown junk come out at first. than take some shop air and do a round about on the circuit, put it back together and should be much better. the jet is between main jet and the front of the carb twards the front of the engine.