Don't have a 914. The jackshaft is a single speed bike hub that I had made into a freewheel and welded on a sprocket to it, to connect to planetary rear end.
http://www.youtube.com/watch?v=_CmPovPH4UI
Posted earlier in wrong area for projects.
Plan to ride in parades next year, with straight pipe only sounds cool.
Got real lucky on putting everything together eye balled it together lol.