Me and the father of my wife (that is my buddy in all my 'experiments' ... ) we have installed our home made left handle throttle
May be it is not refined but wemade it with 50 cents
components are a stirrup of a washing machine, the break lever of mountain-bike (of course, it's a mountain sled

) and a cable taken from a scooter
It seems to work great but I'll can tell only after a test on snow
