I saved this from another forum. The 300 seems to have a unique retention system and just unscrewing the hex screw damages the internals.
"Looking at the parts fiche:*https://www.kawasaki.com/Parts/Parts...017/KLE300*for
the handlebars, it appears the V-X uses a similar retention method to the Honda CB500X/F/R models - where the bar-end weight is screwed to a second insert weight inside the bar itself, and the whole assembly is held in place with a retention spring-clip that allows it to rotate inside the bar, which is why you are having trouble removing the screw/bolt, as the whole thing just spins...
Hope that helps.
Thanks. That did indeed help. For posterity, here's what I found:
To remove the bar-ends, unscrewing the bolt or the bar-end is useless and may damage the clip which is not designed to be turned. Instead, as JMo said, compress the 2 long tabs (visible at the end of the handlebar), and simply withdraw the entire assembly out of the handlebar.
Actually, "simply" is completely incorrect... To get better access to the clips and bar-ends, I dismounted the control switch assemblies and moved the grips (and throttle tube on that side) inboard out of the way. Then I had to find a way to lever the bar-end assembly out of the handlebar. On the first end I removed (clutch side), my clip was already slightly damaged (they can easily be rebent to functional shape) so I used collars and screwdrivers against the end of the bar to pull the assembly out. As mentioned, everything was loctited liberally, and the solid grommet is a substantial press-fit into the handlebar, so it was very reluctant to move. Fortunately, it comes free of the handlebar after about an inch, and then the whole assembly does come out easily. Knowing how/what I was doing made the throttle side easier, but it still felt firmly glued in.
Assembly is the reverse of the above, but you may want to silicone lube the heck out of the solid grommet before insertion. For the time being, I don't plan on re-inserting the originals, as I'll be using universal Acerbis handguards which bolt to the end of the handlebar. I haven't ridden the bike without the bar-ends yet, so I have no idea of how much difference it makes. I'll deal with weights if necessary when I install the handguards.
Incidentally, the parts fiche that JMo referenced is a great resource, but is only avaiable on the US Kawasaki site (Canada's doesn't even mention parts at all). I had looked at it, but the detail was so poor I was unsure until JMo provided the description. Hope this helps as well.