Just got my bike back from having the timing checked for tough starting...Rode about a mile before I noticed that oil was "streaming" down from the bottom of the two half moons of the valve cover of my WR400. Came back home...took off tank...the top two allen head bolts were not tightened at all...almost shaken loose! Would this have also contributed to the new popping that I didn't have before..ie more air being sucked in through the gasket? Tough starting, high idle once started? Thanks for your insight.