I have a stock, relatively low hour (maybe 200 hrs) 2006 WR450 and I am hearing some knocking sounds during low RPM high load conditions. It sounds like a rod knock but I would think a bad rod bearing/wrist pin would knock at all load conditions (i.e. idle, low RPM/high load, high RPM/low load, etc.). It doesn't sound like detonation (I think)......i run 91 octane at about 5000 ft elevation, so I think the chance of detonation is low. There has never been any metal signs in the oil (changed regularly) but the knocking seams to be getting slowly worse over time. Also, it has an aluminum GYTR engine skid plate, which I understand makes these motors seem noisier, but I am getting concerned as I don't want to launch a rod through the side of the motor. I have 2 intake valves that need to be re-shimmed, so when doing so, I will just go ahead and pull the head/cylinder off to check for any play. Is there any other easier way to check the rod bearings without taking off the head and cylinder? Any comments would be greatly appreciated!