Adjust flow of tank filler. I just changed the flapper in my Kohler1.6 toilet but now it takes 10 minutes to fill the tank. How do I adjust the flow?

Changing the flapper should not affect the time it takes the tank to refill. That is unless the flapper is not sealing.
Which type of fill valve do you have?

Harold may be on to something here. Flush the toilet an a minute later add food coloring to the tank. Tell us if it aoppears down in the toilet bowl