did 2 builds with china girl and NT carbs. been a mechanic for over 40yrs and love the simplicty of these things. no problem with needle/jet/float stuff all coming out OK except for idle on #3 build. too lean. has a 4 position needle. position 3 from top too rich all around. position 2 OK all around but too lean at idle. broken in, no vac leaks, #65 jet, 40 oil mix, b6hs, head bolts at 12ft lbs with copper head gasket. raised the float just a bit above the std 21mm and nice idle now !! i have found subtle changes in all these kits/carbs. some needles are longer/shorter, 4 groove/5 groove. clamp has a tab to hold the square nut/no tab, different slide return spring. length of clutch arm short/long. nice casting/bad castings, fine thread/course head studs. they all run different and require different carb settings.