I have a 2000 XR200R. I have what looks like a brass O-ring. Is this what the exhaust gasket looks like? When I install it, the exhaust header pipe is way loose. I can't tighten it any more and there seems to be about 1/4 inch of play. Is this brass O-ring the right exhaust gasket or is the right one about 1/4 to 1/2 inch thick?