You don't need to remove the grips if you're installing new bars. The grips may be difficult to slide on dry. Use an adhesive, I use 3m Weather Strip Adhesive there are a million other things that work and I'm sure everybody is going to list them, and the slip right on with almost no effort. The weater strip adhesive will dry within a couple of minutes. Don't use grease in the throttle tube, it's too tacky. A light oil works just fine. I personally use Tri-Flo with Teflon, again just about anything will work.