I managed to buy a replacement as the original breather had seen better days. Cracked it was cobbing out mucus like oil everywhere Sweet as now.
It's quite normal to get oil mist and pressure from the filler plug if you remove with the engine running. You've got crankcase pressure from the pistons travelling up and down. The area under the filler cap is at "low" pressure, not pump pressure, but you've got the primarys spinning around and the crank splashing the oil around the cases. You'll get oil out of the filler... Tbh, 130 doesn't sound too far out. Comp ratio is about 1:9 on the 750, so without taking all the physics into account, and just simple maths 9 x 1bar is about 130psi. It's more relevant that both cylinders aren't too far apart. The oil around the cooling fins will likely be a leak from one of the o-rings under the head. There's no gasket on the old 2V, so over time the o-rings will harden off and pass oil, especially the ones under pump pressure, feeding the cams.
