Flange nuts are common on Japanese motocycles. Quite q few models may exist, we sell here the most common in standard and fine pitch. The base may be flat or serrated.

 

Japanese motorcycles usually use fine pitches for M10 and above. So you may need M10 x 1.25 and M12 x 1.25 which are not common in hardware stores and overpriced in bike shops.

 

 

Nut Flange