Entire bar end and rod falling out while riding
Luckily I noticed the bar end and the shaft it threads into was falling out of the right side throttle sleeve while I was riding. I grabbed it and shoved it back in.
When I got home I realized it was more than just tightening the screw down on the bar end. Like I said, the entire shaft had slid out. I'm guessing the last owner had aftermarket bar ends on and shoved the stockers back in for me to pick it up.
I found that the metal retaining ring that is around the rubber bushing on the bar end side was simply placed incorrectly (too far towards the bar end) on the rubber bushing. Once I repositioned it correctly it slip in as one piece and snapped in and I haven't had a problem since.
Just thought I'd let this be known in case someone else has the same problem.
Over the past 15 years of riding, every bike I've owned has been to prepare me for a RC51