1) If the grips are worn even a little, save yourself some time and effort and just cut the existing grips off and get a decent set of new ones. They're pretty cheap at ~$10. I just installed a set of ProGrip dual compound grips to help dampen vibration. Note: There is a throttle sized grip, and clutch side grip in a set. Different inner diameters.
2) I used to use grip glue to keep the grips on, but they always twisted due to my frequent death grips on the bike. Now I safety wire them, and they stay put perfectly. Another big benefit is that by safety wiring them, you don't have to deal with messy glue, and swapping grips out is a piece of cake. No more dried up glue to scrape and deal with. You can buy just the safety wire and use regular pliers, or get the fancy safety wire pliers that are a little pricey, but are really trick to use. Make sure your grips have grooves / channels in them for the safety wire.
4) If you're so inclined, now would be the time to replace the cheap and flimsy throttle tube with an aluminum one. I use cable lube or a really light silicone grease on the throttle end of the handlebar so it slides/twists easily.
5) I recommend bark busters from Enduro Engineering (
www.enduroeng.com), along with the brush guards. Make sure the throttle side doesn't stick due to the grip end rubbing on the inside of the bark buster. Leave a good 1/8" clearance. Make sure you keep the throttle tube clean, and if dirt does get in there, clean it out well - sticky throttles are exciting but dangerous!
6) I think you have to cut more than a 1/2" off the ends to get those plugs out. You could drill and tap them to the size of the bolts that secure the bark busters to the ends of the bars for a really secure fit, and save you from busting those plugs out. I worked on mine for about 15 minutes, then said screw it and went and bought a Renthal bar instead.
Hope this helps...