Bolts for Harley risers

Who knows about US bolts sizes? I have 2 sets of Harley style risers and I really would like to know if the bolts for them are 1/2" UNC or UNF spec. What’s the difference? Is it something like the old Whitworth and AF?

hi there theyre probly unc the difference is amount of thread per inch unc is about 18 and unf 24 i think the last letters being for coarse and fine not sure that whitworth etc match up ,try clerkenwell screws on theobalds rd they seem to stock pretty much everything and will gladly help even when the end sale is only a handfull of bolts

Thanks for that. I’ll check out that shop. All the bikes I’ve ever had up to now have been Japanese and everything is easy in metric, but I do like those risers! Sooner or later I’m sure I’ll get my teeth into something hardtailed of British or American origin so it’s good to know contacts like that.