I have the same model engine. It took me a while to figure it out, as the butterflies were staying open, even when it was cool. I thought I had it set up correctly, but I was wrong. The new carb I got just wouldn't work properly, so I cleaned up the old one inside and out, and reinstalled it. It idles better and starts quicker. I contacted the seller, who said it was the correct part number. Once I looked closely at the choke lever I could see the difference. I could modify the new carb by using the choke lever and spring from the old carb, but it wasn't an issue once I got the old carb cleaned and reinstalled. I kept the other carb in case I need a new one in the future. All I will need to do is switch the choke lever and spring.
Maybe you should compare the carbs. It's what helped me to figure it out. Just look at the carb choke levers and see if they are identical.