I have a K & B .45 Sportster engine built for RC planes. The muffler does not have a nipple for the fuel tank pressure line and the documentation with the engine says that the fuel tank needs to be "vented to the atmosphere". How do you vent a fuel tank to the atmosphere when the plane may be upside down at times? Won't the fuel leak from the vent? I am unfamiliar with any system that does not have a pressurized tank using exhaust pressure. Somebody help me please???