I found this on endless and does it make sense or not?
Cut a piece of 1" pvc pipe about an inch or inch and a half long. Glue to the throttle. Use pvc cement sparingly, so you don't glue the throttle so it can't rotate. That's it. If you have some old shifter parts laying around, the inner part of the grip shifter makes a nice sleeve to go between the bars and the pipe. If not, just a scrap of flat thin plastic will do. The pipe is just slightly oversize.
Cut a piece of 1" pvc pipe about an inch or inch and a half long. Glue to the throttle. Use pvc cement sparingly, so you don't glue the throttle so it can't rotate. That's it. If you have some old shifter parts laying around, the inner part of the grip shifter makes a nice sleeve to go between the bars and the pipe. If not, just a scrap of flat thin plastic will do. The pipe is just slightly oversize.