I often cut my own gaskets. When doing so on one of my B&S engines (8.75 OHV Professional Series on a Deere push mower), I had a bit of difficulty lining up & cutting the opening circled in orange on the gasket. It mates up to the hole also in orange on the carb. Then I stopped to think, what is this opening for? On a carb off of a standard 6.75, 7.0, 7,25, etc.Briggs flathead, there is also an opening on a slightly different style carb and I believe it is there to facilitate the primer pulse if the engine has a primer bulb. Well and good, but the engine on my Deere has an auto choke, not a primer. So, again, I'm wondering what this opening does? I'll bet someone here knows.