Bolt sizes for motorcycle

Hi Everyone I am about to start work on a Tamiya 1:12 zzr 1400 and wanted to add some aftermarket details mainly fairing and engine bolts and braided hose to begin with, this will be my first foray into aftermarket detailing so can anyone advise me on bolt sizing like 10mm = ?, 6mm=?, 8mm =? these are the most common sizes I`d say or the size of fairing bolts I will be purchasing top studio bolts as they are the easiest to get hold of for me.

Cheers
Marterrin