Partial or half gas load can be achieved when the gas gate valve is 1/4 to 3/4 open. Jet needles and mix tube are competent to regulate the mix in this area. Needles The needle can be adjusted with a clip in 4 different positions. If the engine runs fine with the throttle valve slide fully open, but stutters in the middle, then its too greasy stroke. You can hang the lower jet needle (move the clip higher than the needle) and thus reduce the mix in this area. If the needle is already in the lowest position and the mixture is still too greasy, then use a thicker needle or a smaller mixing tube. If the performance is too low at full throttle then hang the upper needle. The needles are available in a variety of thicknesses, lengths and grades. We recommend that you try out different needle sizes to find which one is best for your personal tuning needs.