Hey, I just picked up a poulan 42cc engine for $10. I need a new jug, but I know where to get parts. I have a question about the intake design. On mine, it has an extra port above the carb with a butterfly valve. It only opens at WOT and is plumed to the airfilter. Maybe a recirculation valve? The piston also has ports, that lead to the transfer ports. I also noticed that when the exhaust port is open, this extra port is also open about half way. In order to use this engine, does it have to have this extra port. I was hoping that i could just block it off, and use a different carb. I am going to take some pics with my phone, and put them on here.