I bought a used hank Scott open motor this winter, and the vent from the case had a line with a larger piece inthe middle of the line with some sort of ball type valve in it. It isn't a one way valve, but has a ball that does move inside this larger piece. What is the purpose of this, and does anyone else use this? I am just using a normal line up to the breather tank. I'll try to post a pic if this doesn't make any sense.......
