Doctorot's '78 KZ1000 build

I can't imagine a builder of Doc's skill is running the chain too tight - however he isn't shy in the "burnout" arena 

The doc wasn't the address this was addressed to...I meant maybe a previous owner, most of us aren't the first owners of our bikes....anyway: a bearing that's sooo a kind destroyed must have a cause, it doesn't happen on its own!!!

DoctoRot wrote:

WA-20 is always a treat

Hwy 20 is a great road and the Washington Pass hairpin is my favorite corner especially westbound. I can take that corner westbound at 60mph on the Concours. Eastbound is off camber and regularly has gravel on the road. Just about every trip we take the first and last day is riding Hwy 20. Lunch in Winthrop at 3 Finger Jack's or on the deck overlooking the river at Carlos 1800 Mexican restaurant.
Now I need to plan another trip over Hwy 20.

 

Unsure as to why the bearing failed. These are the original bearings so that means they have about 90k miles on them at this point. I regularly beat on this bike – burnouts, clutch dumps, I hit the rev limiter everytime I ride it. 

Since this bike is jacked up in the rear and extended swingarm I determined chain slack by removing the shocks, finding the tightspot in the swingarm arc, backing it off a bit. I then made a gauge block that I use to set chain tension. 

It looks like all the balls are still in the bearing - I count 11, the gap is what the cage typically takes up if it were there.  I'm considering a double row bearing from APE.  www.kzzone.com/trans.html  

No need for the Fancy Expenditure DoctoRot! I've plenty of "little" more powerful engines i've built over the years that don't ever require that option of double row output bearing. I believe ZED1015 mentioned an option for output bearing. They are still a 6000series bearing but if you look inside they have a draft/windage area not that that that would matter. 

Since this bike is jacked up in the rear and extended swingarm I determined chain slack by removing the shocks, finding the tightspot in the swingarm arc, backing it off a bit. I then made a gauge block that I use to set chain tension. 

It looks like all the balls are still in the bearing - I count 11, the gap is what the cage typically takes up if it were there.  I'm considering a double row bearing from APE.  www.kzzone.com/trans.html  


Can't do more than what you did to determine the correct sag..1 Perhaps a material defect or fatigue of the bearing's ball cage?...and at the mileage about 145000 km´s , everything can happened....!
 

90K is a crap load of spinning. I Always replace these when going thru an engine. Also interesting, have you ever witnessed a "plastic" cage/separator in the newer bearings? I do a lot of chainsaws and for some reason Stihl decided this a cheaper way to assemble? I see them fail at an alarming rate, at least when the cage goes south it doesn't eat-up the ports.