Not sure what the code requirements for Wisconsin are, but here in Ohio minimum size for the k/s drain is 1-1/2" and vent 1-1/4" (though to see 1-1/4" used here is nearly unheard of). Also, the vent size must increase to 3" twelve inches below and twelve inches above the roof.
All that being said, something to chew on.....
Code requirements are only the minimum requirements and meeting minimum just sometimes isnt good enough in my own personal opinion. Kitchen sink drains drive me crazy. I'm getting ready to rerun my own kitchen sink drain and am going to pipe it in 2". Just an opinion and you know what they say about those, but I really feel like kitchen sink drains should be upsized to 2" per code.
As I said....just an opinion and not really wanting to invite debate. lol