Thank you everyone for your ideas. Well I took off the clutch cover, motor still mounted on the bike, and this is what I found. The gears were bone dry! No lube at all. The gears even started to get pointed as they meshed together but not so bad they can't be used. There was powder, rust colored at the bottom of the case cover. This is either clutch dust or part of the gears. I will hold a magnet to it later to find out. The motor always made a cool whirling noise when it was on I did not know the gears were dry. I don't know how this made the bang and rattle I heard but it is lubed up and quiet now. The manufacture are clowns. The engines have to be opened and inspected before use.
Mark S.