Got this from Custom fasteners site when I was rebuilding my bike, I don't think that they do as much motorcycle stuff these days though.
IMPORTANT - PLEASE READ BEFORE ORDERING METRIC BOLTS.
Metric bolts in M4, M5, M6, M7 and M8 diameters are suitable for both European and Japanese motorcycles and cars.
However, M10 in the standard 1.50 pitch are only suitable as replacements on European machines. They will not fit Japanese vehicles which use their own specialised fine thread. Please see the next section in the catalogue for our specially produced range of M10 and M12 fine thread bolts for Japanese vehicles.
M10(1.25 pitch) and M12(1.25 pitch) FINE THREAD METRIC BOLTS
For use on Japanese motorcycles and cars. M10(1.25) bolts have a 17mm spanner size, M12(1.25) bolts have a l9mm spanner size. The Japanese often
use a smaller size head on their bolts, so please check there is sufficient clearance for the standard size head we supply, before ordering.
NOTES ON METRIC BOLTS
M4 fits spanner size 7mm. M4 thread pitch is 0.70mm.
M5 fits spanner size 8mm. M5 thread pitch is 0.80mm.
M6 fits spanner size 10mm. M6 thread pitch is 1.00mm.
M7 fits spanner size 11mm. M7 thread pitch is 1.00mm.
M8 fits spanner size 13mm. (Japanese M8 bolts use 12mm spanner size). M8 thread pitch is 1.25mm.
M10 fits spanner size 17mm. M10 thread pitch is 1.50mm.
Cheers
Dennis