I'm having trouble over here in the uk getting a head gasket for my tri-z, i've done some searches on here and some people say that the 1983 yz250k is the same and others say the 1985 yz 250 is the same, can someone who knows for sure tell me the exact year that i need. also is there a difference between the cylinders and gaskets on the 85, 85-1/2, or the 86 tri-z's, thanks guys i'm finding this site a great source for information.