I just bought a 04, CRF450R. I have ridden it 4 times and then decided to check the coolant. It was empty. I'm not sure if I bought it empty or not. I took it in and the service agent said it was leaking because of a bad gasket on the impeller. They replaced that gasket and then did a test ride. Now, according to them, it is leaking out of the overflow tube. They are now telling me that I blew the head gasket, which will take another three days. Are they telling me the truth?