I'm going to make an extension boss to move the O2 sensor out a bit, anyone know what the thread size is as my motor is a few hundred miles away at the mo'.

Al

 

I fitted a Revolution downpipe which had two bosses welded on it, one at the top, one at the bottom.
Don't know if both bosses have same thread but the bottom one was blanked off with a 12mm metric fine bolt (1.25mm thread pitch). It was the same thread as the wheel nuts.

A

 

Thanks Alan,
I would have thought it was metric, just saves me having to make 3 or 4 different sized ones. Who says I've got too much time on my hands

Al