Dear Ray, try my method, its simple:
Take the carb out from the motor, and look the carb from the lower part, with the rotor fully opened ,the slow speed needle should be exactly in the half portion of the slot (the slot that resembles an "eye" in format), so adjust with an screwdriver (opening or closing the needle) until reach this ideal position.
mount the carb again, and this should give you a super smooth idle.
Minor adjustments may be required given the fuel type and altitude, but this method work very well indeed,
best wishes
Carlo
Brazil