I would agree with Coleighf. The head gaskets are one of this bikes weak points. Even Kawasaki acknowledged this as in addition to the 8 head bolts they added 3 extra bolts underneath around the can chain chamber to try and keep things tight and leak free. As Coleighf says you will need to remove the head and replace the head gasket. That is a comparatively straight forward job. Its when the barrels need to come off that problems may occur. I can supply head gasket and maybe valve stem seals but will need to check for those.