Hi all, I need some advice. I'm trying to help out a friend who's bike suddenly started making a terrible noise while in my possesion. It is a 1997 XR650L. We were driving along a dirt road fairly slowly and came to a stop, the bike died at idle which is very unusual for this bike. Started it back up and went a little further then it died again. This time when it started back up it was making a loud knocking noise, it is there at idle and when you pick up the revs, seems to be louder on the right side. We shut it down immediatly but I don't know what is wrong. It is blowing a small amount of smoke when cold. I took off the valve covers and checked the clearance, it seemed to be ok *see below for my question on that. I was curious if oil was getting up there so I turned over the engine while taking each of the covers off one at a time. The two on the left sprayed all over and made a terrible mess, the two on the right I couldn't really see if any oil was there at all. Is this normal or should all 4 make a big mess? Anyone have any ideas what is wrong and what I should look for first if I start to take it apart? *about the clearance. On my bike I have always kept sticking feelers in until one didn't fit and the one below that I declared was the clearance. The manual for the XR says to use the one that drags a little. That seems so ambiguous, there are about 4 different feelers I could say that about. How do you all go about checking the clearance? Thanks guys!