Like Rooster said try all that first. If it still surges and you want to try the adjustable high speed needle you will need the right one. I dont think the one out of the 10 hp carb. will work. It is too short. The high speed jet on a Walbro LMT carb is the little brass jet that screws in from the side of the aluminum post that the bowl fastens to. Once the bowl is removed it is easy to see. IT HAS TO BE REMOVED if you are going to use the adjustable needle that EC sells. The point of the needle is long enough so that it goes up inside the emulsion tube, which is the brass screw head that looks like a jet if you look straight up into the bottom of the aluminum body once the bolt that holds the bowl on is removed. It threads into the same hole as the bolt that holds the bowl on. What it does, is turns the emulsion tube into an adjustable jet, the further out you turn the screw, the more gas is sucked up the tube. Once again, make sure you remove the main jet. If you do not, it won't matter how far out you turn the adjustable needle because the main jet will only allow a certain amount of gas through and that's it. If your adjustable needle is too short to reach up inside the emulsion tube, it will run way too rich and probably flood out. There was a post on here somewhere with the part number of the adjustable needle assy for the LMT carb.