I would scuff inside the grips with a scotch bright and then clean with CRC break clean (break clean @Walmart $4.00) Sand the handlebar and throttle pipe with coarse sandpaper and clean well. Coat ID & OD with Contact cement let this dry. ( I use Grip Glue or 3M brand from Home Depot) Then I use a very small amount of the break clean to slide the grips on.