I own a 2007 CRF450 that I bought used in February. I took it out for its maiden voyage yesterday and durin about the first 20-30 minutes, I noticed the smell of burning oil. Initionally, I thought maybe it was blow-by past the rings. I kept plugging away at laps and also noted a ringing sound when I pulled in the clutch lever. When I got the bike on the stand, I discovered a silver dollar sized hole just in from the water pump housing between the transmission cover and the right side case. It definately looks like something "left" the transmission. I rode it for awhile before the discovery. I soon will post pictures and will also drain the remainder, if any, amount of oil. I don't know where to start. What did I trash as I continued to ride it unaware of the blow out? What might have failed? I know this will not be cheap to replace. The previous owner stated it had low miles on the motor and everything looks to have little wear. The transmission operated smoothly and I didn't notice anything rough during the ride. Even after the case was trashed. HELP!