Temp gauge, Oh goody. There are no specs on the temp ranges for these engines. 300 degrees, whatever. I usually tell people to avoid those with a temp gun since they are pointing that thing at an item and it tells you nothing. Hows the airflow through the cowl.

I did notice you said it was inverted. if the fuel tank is mounted it the stock position, that is 1st on the list of problems and until you fix it, you will continue to have problems that a temp gauge willnot fix