OK, I now can recognize the insulator in your picture. Now you have me wondering if I should take my YF off and check to see if my hole/gasket/insulator notches line up. My engine runs great and I get 17 MPG. Have you tried it as is? The gasket is pretty thick and might allow the vent to work. I'd be scared to run it without the insulator. You are likely to overheat the carb bowl and boil the gas in it.
