Originally Posted by sofasurferlinux
The bike is an old Huffy. The motor is from ZoomBicycles on ebay. It is mounted to the frame via the basic factory mounts.
I posted a link on engine mounting... Did you look at it. Do your mounts "both front and rear" match up to the tubes as depicted in photos? I find it hard that the engine is mounted correctly to that frame, have never had one do it with the curved front bar...always customized front mount. Can you move the engine at all
This much gap could cause vibration. Are your engine mounting nuts tight enough? Minimum 60 inch pounds. If the nuts back off consider double nuts or lock nuts. I have found that sometimes that you don't get the nuts tighten correctly because of lack of room..this is how I corrected that.