So a freind of mine sunk his yz450f in a muddy pond a while back. We have completley torn the motor apart and replaced EVERYTHING on the inside. WE just got the bottom end put together and now we are ready to put the head back on. The head has got some sand particles all over it and its pretty oily. We are looking to give it a good cleaning before installing it. What can we use to clean it? we were thinking mineral spirits, but i dont know if that will damage the valve seals. Anyone have any suggestions on what we can use to clean the head that will be safe for all the components in the head??? Thanks.