That would be a bit of a safety concern me thinks. Wouldn't that make it more susceptible to getting stuck wide open? I guess it would be possible though. Open up your throttle housing and have a squiz. It's easy to put back together.
You're gonna need a different throttle spring. Try tightening your bar end just a tad. It'll rub on the grip and give it more resistance. I know, it's pretty ghetto, but i did the reverse as i thought it was too much resistance so i just put a small washer in between the bar-end and clip-on. Try it out!