Xs400J air box bolt ID? DOHC

[franticvike]

I seem to be missing a bike for the right side of my air box. Directly beneath the battery.

I think it's number 27 in this diagram but all sites I can find show it as unavailable. Anyone know the thread spec and size of bolt?

https://www.partzilla.com/catalog/yamaha/motorcycle/1982/xs400j/air-cleaner

 

[franticvike]

Ah never mind, I see that the backing "nut bar" (no 9 in the parts fiche above) had just fallen loose into the air box.

Looking at it though it's not immediately obvious what this thing does. Any insight?