I tried to replace upper motor mount one side would loosening up but only at the end of bolt but the other side is loose like nothing there it want tighting up but other side will any help getting it off would be great

 

I and it is a 250 polaris

 

Air tools really help if you have em. Sounds like the motor mount may have separated if one side just turns and the other side is ok. If you can get a small pry bar or some thing to wedge against the inside of the frame mount,you may be able to put pressure on the plate and be able to impact the nut off.