Hey Martin , turn the mix screw all the way in with the eng idoling and at normal eng temp , it may start to stumble if it does stunble or start to die back the screw out just a little at a time no more than a 1/4 turn let it stabilize and then another turn until the eng speed starts going up, at about 1 3/4 turns from the inward seat , the eng will start to slow down again now turn the screw back in clockwise bringing the speed back up and then turn it in just enough to drop the rpm 50 rpm and then set your curb idol speed to around 800 rpm and you should be in good shape Jerry