All the oil feed drillings on the exhaust side were either missing or only partly aligning with the oil groove in the follower (when in the closed position) on my cylinder head. As Dave explains, opening up the lower end with a dremel significantly improved, but did not completly cure it. The final cure was to eliminate air in the oil by fitting a drysump system.
Edited by - Englishmaninwales on 6 May 2009 15:09:19