how fast is the motor idling?, you will need to set up a fast idle to keep the motor running on one "pot" until you get the idle mixture right for that cylinder , slowly adjust the mixture until you get an even idle, slow the idle by backing off the slide adjusting screw.Repeat the procedure for the other cylinder.When you reconnect both plug leads the motor will be on fast idle, back off each slide screw an EQUAL amount to set a slow idle.A word of caution -- if you are running a Boyer electronic ignition make sure that you have a plug connected to the lead that you remove and ground it against the cyl. head, the Boyer black box can be damaged if you do not do this. Good luck, James.