If those All balls bearing in the link you used...There're sealed bearings...So the oil is not from the carrier but from someplace elseI thought ALL Balls was good, sorry. Here is the link
Bearings typically fail from water and dirt contamination. The All Balls Rear Carrier Bearing Upgrade Kit was developed and designed for the difficult operating environment of the powersport industry. Kit contains ball bearings and seals - all that is required to successfully upgrade a rear...www.motosport.com
The rear (axle) is solid. Not loose, no seizing, no grinding.
Why would engine oil be dripping way back there by (under) the carrier and/or why would those carrier bearings get so hot they are leaking "oil like"?
Places to look ,head cover, starter limiter gear cover, the shifter seal, front sprocket seal, clutch release & yes the cam chain tensioner gasket...After further review.. I believe it's oil coming from the short sprocket area, running down swingarm and dripping off the rear carrier. I have had this oil leak discussed here before and I do not know where is't coming from. Maybe coming from when the clutch is engaged behind the engine (since that is right above the small sprocket)? or would the tensioner leak oil? I am ruling out the breather hose for now, however oil is also on the starter motor and running down the left side flywheel case. (the flywheel case/gasket is solid - that is not the problem.)