GPz550 #3 Rod Knock Probable Cause

We "flute' the rod journal oil holes to keep more oil at the bearing surface. Corey, did we do your crank on the last project?

Jay

Thanks for the replies Gentlemen.

Jay,
No, I didn't send you the crank or rods, but that's now on the list of things to send in. Can't afford cutting that corner, if I plan on a complete rebuild. Overkill? Might be, but I'd like to do this once, and right.

Looking at the other rod bearings, what does anyone think caused the pitting? Could it just be poor oil? Nothing looks overheated. I'm not the original owner either.

My $0.02

Pitting is caused by chemical action due to acid build up in the oil from extended drain interval.

Physical damage due to dirt/carbon in the oil caused by oil bypassing the filter from extended drain intervals.

Perhaps previous owner didn't realize that oil changes were required periodically??

Thanks for the 2 cents.

Another thing is with a lot of our bikes, some with very low mileage, is oil breakdown, I'm a big fan of changing that oil and filter ASAP after buying a used bike. Oil, being lighter in weight than water, will allow moisture/gunk/muck to settle in the bottom of the oil pan, and when first started, if there's enough, it gets sucked up, and displaces it everywhere. Fuel from internally leaking carbs, will also break down the oil. So much working against clean and good lubricating bearing surfaces here. Kind of makes you want to go out and change the oil and filter after reading this? I did mine on the current engine in my ride, just yesterday.

Dropping the oil pan to inspect what's in there, or what it looks like, should be high on anyone's "to do" list.