You need to put JB-Weld on the bottom back of the freewheel sprocket so it doesn't work loose in use. All the freewheels I have ever had are like this, and have unscrewed themselves in use, and fell apart. You should also make a chain shroud to fit around the back sprocket to help the chain stay on, along with making sure the chain is aligned right. I did it on the left side of my bike by just reversing the polarity "+ and - power" to make my motor run backwards. Also you may have to meltwork the motor mount to get the chain to align right. Or you can just take it to a real mechanic and dish out some money if you can't do it right yourself. It is not Aerospace science engineering, but it does take some engineering skill. Sorry, not trying to be a smartass just giving you the truth. Also you need to go the Ace and invest in some Grade A bolts to mount everything with. The bolts and nuts it comes with are cheap and will stripout with use. If you get a flat your going to have to take the wheel off, and that means at least loosening the motor mount and mounting it back right. But that's not all, you will just have to figure it out for yourself or pay someone else, and that's just part of owning an ebike. Life sucks and then you die!
Matthew 
