Kuryaken grips require glue. I first used it on my VStar and I only used half a tube. The grip stayed on but would twist on the lower side. I installed the same grips on my Ultra, used the entire tube, and it is on there for good. I would rather have them on tight then the alternative.
I installed the Kury ISO grips on my RKC a few months ago. I used the glue that came with them. On these grips, you NEED to use glue for the left side, as it is not secured by the switch housing (as genuine HD grips are). The glue worked good... But about a month ago, I decided to try a different grip. To get the Kury off, I just grabbed a very tight hold on the grip, and started to twist back & forth. It came loose and slid right off. No damage to the grip or the handlebar. In fact, I just sold the grips yesterday to a guy. You coudn't even tell that they had been previously installed on a bike (yes, I did sell them as "used").