Just came back yesterday from a 310 mile tourist route (great trip/day!!) when I wanted to fill some oil. Whilst I had the bike still running I opened the crankcase filler plug and noted quite a bit of pressure from the crankcase and oil sputtering out. From previous times I remember that there always was an under pressure, but definitely not this time. Bike runs great, so rather puzzled here! What do you experience if you have run the bike for a good while and open the filler plug? Cheers, Rene

There should always be a slight vacuum when running and that will very quickly go to atmospheric pressure when the engine stops.
Maybe there is a blockage where the crankcase breather is connected at the plenum at the rear of the TBs.