old school hairsprayI can't say what the factory uses.
For Soft grips: Bicycle or dirt bike style:
I have always had good results with Aqua Net hair spray. Spraying the inside of the grip with a heavy wet coat, slide the now sloppy grip onto the throttle sleeve and leave it overnight to dry. Has to be removed with a sharp blade or by blasting shop air through a very tight blower, aimed between the grip and the bar..
That i have used don't require glue. The proper grip should have a groove that interlocks with the handlebar switch housing that prevents the grip from siding off.
Are you sure that grip is designed for your bike?
I ask because of the throttle tube vs a hard grip. It can be done using RTV and allowed plenty of dry time.