To all
Well, bike fully re-assembled, still running rough at idle, kept cutting out with loud "Phuttt" sound. Suspected loose plug, checked and renewed both plugs, still at a loss until young neighbour (BMW F650) observed source of sound as "somewhere under the airbox" lifted airbox carefully to find vacuum hose from airbox valve to induction stub badly perished and split, replaced. Another vacuum hose alongside it going across to the other induction stub also perished, replaced. Result: bike now running sweet as a nut, sounding good, and going as my old friend Elvis LeBeau of Baton Rouge would say "like a racoon with its ass on fire!". These hoses are on the right hand side of the engine as viewed from the seating position and run from the airbox to the respective inlet stubs. The hose used by the factory is a relatively thin wall 1.5mm or one eighths thick and internally wire wound. You will need to find something similar for replacement because fitting is a little tight in places. As you probably know the wire binding prevents collapse under vacuum. All in all a worthwile exercise as the engine seems to be breathing a lot better and the exhaust is running cooler. Replacing the oxygen sensor is another thing that I would reccommend, (if you have around 30k mileage) but when you order one verify the length of cable to connector that will be supplied.