I was driving along and things did not sound right to begin with, then I smelt burning and pulled over in a layby in time to see smoke coming through the vents.
There was oil everywhere, it seems to have come from the filler vent. The only other thing visibly ammiss was that the air cleaner hose had come off the top of the carburettor.
Is it possible that a lack of vacuum on the crancase vent on the rocker cover, caused by the air hose being adrift could have caused the valve to stay shut causing a build up of back pressure with no where to vent but the filler ?
Engine seems to be running fine, so is there any other cause of a sudden oil pressure build up anyone can think of.