Hi friends... I have a question about the operation of the mixing screw. What is the function of this screw? Will it be to increase or decrease the air in the mix? Will it be to increase or decrease the fuel in the mix? Will it be to increase or decrease the mixture itself in the cylinder? Currently I have the screw with three turns out ... and the spark plugs are soaked with gasoline. Thanks
Although mostly referred to as a fuel screw (including by me), it is actually a fuel-air screw. It is used to set the idle mixture and also overlaps off-idle. Screwing it out creates a richer mixture. Air enters via the pilot air circuit in the mouth of the carb, and many carbs have a removable air jet. It then mixes with fuel drawn via the pilot jet. The main and pilot jet look identical and it is easy to mix them up. The 'n' turns out should be considered a starting point only. See https://litetek.co/Guide_FuelScrews.html
If you are seeing large amounts of excess fuel then check that your float needles are in good condition and both assembled and sealing correctly. check fuel level see this guide https://litetek.co/Guide_Mikuni_BDST_Fuel_Level.html Check that the fuel pump is functioning correctly and is a low pressure pump as per OEM