Does anyone know what thread the fan switch is? I have seen on here where one they mentioned was 1/8NPT, and another was 1/2 NPT. The thing concerning me is, should it not be metric? Just don't want to pull it to find out.

 

Not sure of the size but it's a generic part, it fits my 94 CBR1000F, 97 GL1500, XRV750RD07a.
If you have a problem with the fan not cutting in, check the earth is making a good contact. They're too expensive not to check this first - I know

 

Can't comment on size but I got a Chinese copy part for around £2 from the bay. Ironically mine started working a week or two back!