Thanks to everyone hear. I had seen posts about this plug falling out and was familiar with the TT piece that is sold to plug this hole. Last night my neighbor dropped by. He was concerned with an oil leak on his YZF 450, 2004 model. Thanks to you guys I was able to walk right up to the right side of the bike and find the leak. He bought the Yamaha part but has the better TT plug on order from a local dealer. Just wanted to thank everyone for making me look so smart. Is it just dumb luck when the plug falls out or is it owner related?