Does anyone know the temp sender thread size ?
wouldn't happen to be M6 1.0mm would it by chance ?

looking for a temp sender for my trailtech voyager and would rather one of these over the copping of a hose and inline type

It's some kind of odd thread. I know from trying to find out myself. The TrailTech senders will fit in the original Honda temp sensor position though so you don't need to mount one in a pipe.

Why not just try a bolt in the head to check size.