I recently bought an 03 cbr600rr, which was almost completely rebuilt from a bad wreck. I finished the project, and even after sitting for a year before I bought it, it fired right up. everything checked out great until it really started to warm up, where I found an oil leak. It appears to be coming from the small hole just below the exhaust port on the far right cylinder, and I am wondering what that hole is, and if its even possible for it to leak from there. I was thinking head gasketbefore, but it seems to be this hole. Any help is greatly appreciated!

 

check the valve cover gasket!!to the best of my knowledge the holes go up into the
spark plug holes-used for moisture control

 

Damn, maybe it was oil in there from being worked on and its leaking its way out now. It wasnt the valve cover gasket. Thanks for the post though, ill start lookin!

 

I looked down through the hole the spark plug goes in and noticed that the gasket for the valve cover is pinched off there, so if that hole is to let moisture out of there, im guessing the oil is splashing up into that hole and running down and out. I didnt realize from the other post what you meant about the valve cover gasket being at the top of the plug hole. Thanks a lot!