Take a Pic of the head and the cylinder. It's possible that your head has a small hole on the inlet side like a BZM head. I will take of the head of my polini engine when I'm at home to show you what I mean.
That's correct what kitty says this transmission is not made for the power of a polini engine.
Mine doesn't have one like that at all. And i was wondering about the flow thats why i put it on like i did but now u sharing this info answered a lot thank you. With a gasket like that it would direct the flow