Triumph Twin Breather

[walworth]

I have a Triumph 5TA distributor engine in a trials frame, and currently have the engine out for repairs. I have noticed a lot of twins with breathers out of the dizzy mounting hole. When making this mod do I blank off the original breather, and remove the associated disc valve?, or do I run both systems? I always worry about water entering through the original breather when in deep water sections, but I have never seen any evidence of this happening. I would like to alleviate this worry, if I can.

I have also seen a few bikes breathing out of the primary case, I presume this means taking out the seal between the crankcase and primary, but does this include drilling a hole and allowing the engine oil from the bottom of the crankcase to drain ino the primary, as I know some B40s have adopted this system? What would be the advantages of this system? I would appreciate some advice gents, if you can.