I have enough trouble keeping just one sprocket lined up with enough clearance for everything. When I was using a chain tensioner I even had problems keeping the chain on the sprocket so i got rid of the tensioner altogether after reading this thread http://motorbicycling.com/f6/increme...ement-265.html
If you get it to work, be sure to report back with pictures! You will need to put an alternative starter on because I don't think bump starting willl be an option any more. I live on the side of a mountain so I am very interested any manner of gearing down for the hills. Discretionary funds are too short for a jackshaft kit so still in the scheming and dreaming stage.