Does anyone know what size nut to use.

I wanted to fit mine today, but the M10 nuts I had wouldn't go on

Could be 10mmx1.25mm the Japanese tend to use finer pitch threads than europeans. The only way to tell is to find a nut that fits or measure the threads using a pitch gauge

or get a normal M8 bolt, and put the threads together.

if it's the same thread pitch, it's M10x1.25. cheaper than pitch gauges

my bike indicators had the same thread. pita!
tom

yep, last bike indicators I fiddled with had m10x1.25 threads (instead of our normal metric coarse at 10x1.5)

Spot on.

My local fasteners place (I could spend all day in there, they have almost everything) had them 25p each. Fitted straight away (M10 x 1.25).

Thanks
Rob