No Bill its not the breather although Its a new piston barrel assembly so pressure will be high I have one of Bens PCV valves they are not the problem they handled all the big Egli pressures I am beginning think it may be the crankcase recess for the tubes is wrong I was hoping that two new pushrod tubes would sort it out but then I thought that assembly of O rings suggested on here would before
. I would fit a pair of Flash solid tubes I have but the angle to the head is too acute. I also thought about turning up some bigger OD alloy ones perhaps with a screw on lower flange but you know what... its such a PIA to sort once the bikes built and I have missed so many months of riding last year and dwelt in the workshop so long I think I will get on it, ride it, and enjoy the spring and just carry an oily rag