Re: checking in from Western Ma.
I keep saying this over and over but if it is possible remove the tensioner and adjust the rear wheel for the motor side chain. If necessary move the tensioner to the bike side chain much less pressure on it there. I heard it before I built my first one and then I finally did it after I wrecked a wheel and the darn chain still would not stay on. I haven't had a bit of trouble since.
My posts have entertainment value only. A bike ain't yours till it has your blood on it. Then it owns you.