krank vent breather

this concerns a BMW R60/2 ...I put a krank vent breather on it and it never stops working. I have used it on Nortons and usually it makes noise at idle and low speed but stops or greatly slows up as the rpm's climb. Not so here. I wonder where it could be getting it's air supply. The old breather is closed off, there is no smoke in the exhaust from bad rings, it runs and idles very well, plugs are dry, there is no discharge from the vent hose, all seems to be well. But the breather keeps hammering throughout the rpm range and I can hear it through my helmet. There is a slight seeping of oil at the cylinder base. Little or no leakage from the rear main seal. It is possible it is sucking air inward through the cylinder base but I would expect a bigger oil loss. The next thing is to take it to a friends shop and do a leakdown and compression check. Any ideas?