In reply to # 1512174 by grumpicus OK, so you believe that the '12 flats down' position is completely random - fine, that's your opinion.This all started because you said , and I quote ,
"If you're having to turn the adjusting nut through a turn or two to make a difference, there's something else wrong...."
If they were adjusted to level , all the way up , lean as can be , a turn down is still rich . It will take more than a turn just to get to 12 flats down . You indicated that there would be another problem other than just the need to dial in the carbs . I object to telling him to look elsewhere when he is doing an initial dial in of the carbs he has just installed . I think he should adjust the carbs to suit the motor he has just installed them on .