Wilsons Sandbox

I looked at the pictures, and have some observations.  First, this engine has been starved for oil at some point.  On a KLR, the lower end is quite robust, so seeing bearing failure is unusual.  The balancer shaft bearing that failed is one of the upper ones, so if there was a shortage of oil, it would not get splashed.  The same for the small end of the con rod.  You said that the owner did a lot of highway riding.  I would venture a guess that he liked to run the bike fast, and did not add oil at gas stops.

  

When I rode the Trans Lab Hwy many years ago, I ran my KLR at 75-80 MPH with stock gearing on the trip up and back.  I would have to top up the oil at every gas stop, and carried a couple of quarts of oil.  This was alarming to me, but on inquiry, found that it was not unusual. Subsequent trips showed that 5300 rpm was the point where oil consumption went up.  On my trip to Prudhoe Bay from Atlanta, I used 5300 rpm as my cruise speed.  My KLR only needed topping up every couple of mornings.  Over the years, lots of KLRs have ended up being parted out when the owner has run it out of oil trying to get home.  I have used a lot of different oils in a KLR.  The best oil is enough oil.

The other observation is about the copper powder which is around the main bearings on the crank.  This is probably the flash copper which is plated on parts where the manufacturer  does not want case hardening to occur.  It is similar to the copper which is deposited under decorative chrome to remove surface blemishes.  I seem to recall that the main bearings rollers on a KLR are in direct contact with the crank shaft (no race).  This would require these areas of the crank to be treated in a gas while being heated (today probably nitriding) and perhaps induction heat treating before grinding the surface.  This copper plating insures that the gas will treat only the areas around the races and not affect the toughness of the rest of the crank.  It is not unusual to see this powder, but more so on engines that have been run out of oil, overheated, or thrashed at high RPMs for extended periods.  High temps cause it to flake off.  

Thanks for letting us share in the findings.  The pictures are quite informative.  It is a good thing that you did not simply try to replace that bearing.  There are several problems with this engine(can O' worms).  I actually knew that the balancer bearings needed to be pulled from the inside--I thought my bike had a bad one.  Think of spinning a bicycle wheel and sitting on a swivel chair.  The spinning weights need to be contained in all directions.  By the time I read through what was going on, you had already figured it out, so I did not butt in.  

Cheers, 

Doug