Warm the engine up,shut it down,screw all 4 mixture screws in until they lightly seat.back all 4 out 1.5 turns,start the engine and turn all 4 in or out 1/4 turn at a time until you get the highest idle speed.you may need to slow the idle sped down as you do this if the screws were set way rich.after you find your highest idle sped richen the mixture 1/8 turn on each screw.this will put you in the ball park.Bill