while riding at 55 or so i recently heard a popping noise like i blew a tire, no other concerns noticed, i kept riding all ok, but there was a puff of smoke i think. Yesterday while riding home from work, it happened again, while on the freeway. I then smelled burning oil, noticed smoke pouring out the back of the bike. After trailering home and dissassembly i found the valve cover gasket had a section blown out of it. Anyone heard of this, or what would cause the crankcase pressure to build this high? Please help....