I have done some searching on this. I have read that if you don't cover the hole it will cause an air leak. I also read if you do cover it then it will create a vacuum when the slide goes up and down. It looks to me like it needs to be open. They went out our their way to cut the slot in the anchor. I just popped open one of the carbs I got for the free shee and the hole was covered. Is anybody 100% sure which way to install the anchor? I will call CPW tomorrow and post results if nobody knows. I agree with AWK in this thread I just want to make sure. I have them open on the other bikes.
http://www.blasterforum.com/carburetor-138/needle-53421/
http://www.blasterforum.com/carburetor-138/needle-53421/