How does the installation of a Harley Heavy Breather, pictured above, stop the external oil drip from an M8 intake system.

 

well I was figuring it would mitigate or eliminate it because it is more sealed/contained..the previous one we had on different bike worked like that anyway

 

Because the filter is past and in front of the breather vent hoses. But it does nothing to keep the oil mist out of the engine.

 

There are many reasons why oil may end up on the side of a bike.

This video addresses some of them-