All: The oil pump on my 2000 XR650R exploded in Baja. Up until then the bike seemed to be running running fine. Then I saw it wasn't getting oil to the frame reservoir after a thorough warm-up and was blowing oil out the crankcase vent into the airbox. First I checked for clogged oil lines and they were clear. So I pulled the right case half in a motel parking lot. The outer impeller (the pump that pulls from the frame reservoir and feeds the engine) looked fine. The inner impeller (the pump that pulls from the bottom of the case and pumps to the frame reservoir) was in pieces. 2 weeks ago I exploded a couple clutch discs and both filter screens and the bottom of the case had many aluminum chips. I think chips jammed the impeller and caused it to detonate. Before the trip I flushed the engine multiple times with kerosene and changed the oil 4 times. Here is the question. Looking at the oil flow diagram in the shop manual, it shows that the paper oil filter as the last step of protection before the oil gets to the engine and the transmission. The inside of the paper filter looked clean. From the diagram it looks like I don't need to worry about aluminum chips in my engine and tranny. I have torn down a bunch of 2 stroke motors. This is the first 4 stroke. Do I need to split the cases on this engine to make sure no aluminum got into it? Is there any other way to make sure all the passages in the engine and tranny are clear and not obstructed by aluminum chips? Thanks!