I recently changed the front sprocket on my 93 TRX200D Fourtrax Type II. When I removed the sprocket cover, the lower bolt hole began to leak oil. I quickly put the bolt back in and went about changing the sprocket. When I tightened that bolt back it didn't get snug and feels like something is stripped inside the crankcase. The last couple of threads on the bold are booger'd up and I'm hoping that a new bolt will solve the problem. My real question is "Why is oil leaking out of a bolt hole?" Is this normal or do I have some larger problem inside the motor? I have a repair manual but it doesn't answer this question. I am putting a link to the diagram of the Left Side Crankcase Cover for better explaination. The bolt I am referring to is #31. Any help would be greatly appreciated.

1993 Honda ATV Parts for TRX200D FOURTRAX TYPE II, Engine & Exhaust - LEFT CRANKCASE COVER