I called pro-tec they said 107.5 main, 65 pilot, 2.0 ns, 80g spring I allways ran high speed screws at 2 turns and low speed screws at 1 1/2 turns, my plug burn was always perfect, I ran that on several boats. as allways no two boats are exactly the same, so I would start there check plug burn and make adjustments. One thing I ran into was they would load up if you idled to long, the explination I was given was that the 61x cases had a smaller intake area and could not use all the fuel that dual carbs had (this might explain the smaller jet sizes). again right of of idle and on they work very well and I allways thought they ran as good as 62t cases with the dual 38s. hope this helps you!