Out riding yesteray and noticed a burning oil smell, pulled off the track only to notice oil dripping off the radiator onto the head pipe and the engine's top end became really noisy!!! I thought, oh shiii, I must have lost enough oil to burn up the top end... What I found was there is a plug on the front side of the cylinder, to the right of where the exaust pipe mounts, that somehow came out.. I think it is on the exhaust side of the valves but not sure. Under idle, the port pulls air in, likely because it opens a closed circuit under pressure. But it also must work in the opposite under revs and blow air / oil by, thus the oil loss.. I found by plugging it back off under idle my suspected engine noise goes away, thank God. Parts book calls it a " Plug ". Weird deal. I was also using an approximate 70/30 race gas mixture, but I don't think the high octane gas was the cause. Anybody else seen this yet?? Thanks, Dirtstiff.