How to remove the original grips without destroying them

Instead of WD40.... I prefer to use a cheap carburetor cleaner, it's much quicker and doesn't leave a [dangerous] oily residue inside. Slide a skinny screwdriver under the grip, shoot a tiny bit of carb cleaner in alongside it, and start sliding the driver sideways. One or two shots is usually all that's required, and that grip is off in seconds. You should cover any of your exposed painted parts if you're worried about overspray (that's why I use the cheap stuff, because some brands, like "Chemtool B12" will eat paint FAST!). Worked at a bike shop for 18 years, been doing it this way since the 1970s!!! Friedrich Heinrich