[88 slingshot 750 carbs issues]

Don't reckon there's anyway the carb body has a crack or, like you said maybe the cleaning process opened up plugged circuit. 

[Interchangeability of carbs and carb rubbers for oil-cooled engines]

I learned something today, even though the old 750-1000 air cooled Kawasakis are close to the same spacing as the Suzuki they're a little different. Kawasaki is 75-96-75 when you line up the 2 intake to intake you can see the difference. But the Kawasaki's will work on the Suzuki's with a persuasion.