Dreaded Oring oil leak head-cyl!

[greenmonster]

A bit frustrated, have oil leaks on both my Monster & 907, on hz head-cyl, oil line at exhaust valve.

Is there a fix f that?
Tried 0,5mm thicker Orings w 907 w no good results. 

[Norm]

Are you referring to the external drain line where in attaches to the head or the mating surface between the head and jug?

[greenmonster]

Mating head-jug.

[Norm]

Check your "freeze" plugs, if/when those leak, they need new ones and need to be a TIGHT fit (FHE ).

[greenmonster]

OK, thx.