Dome nuts

Hello, having recently purchased a Dax ST50, I noticed that the front engine cover, is held on by 3 domed nuts and one plain nut. Assumed this to be incorrect, so replaced them with 4 nice new shiny chrome ones.
However, looking at pictures in the manual, it clearly shows that it should have 3 domed, and 1 plain.
Anyone out there know why? Thanks, from confused of Exeter

Hi
3 dome nuts and 1 plain nut which should have a thick copper washer in the dim distant past I am sure I was told the plain one indicated the oil way but I am getting old and senile
Regards Tufty

There's lots of theories on why Mr Honda chose to have one plain nut and three domed ones.
One good one is that you can use it to lock two nuts together to fit/remove a cylinder/head stud.
Sounds reasonable?

The plain nut actually goes on the lower RHS stud (as you look at the cover), so not on the oil feed (which is on LHS).....



V.