parts for CB77

[conbs]

Graham, Aren't the 6, 8 and 10mm JIS thread pitch the same as current standard metric thread pitch? I was thought only 3, 4, 5 and 12 mm JIS were different.

[G-Man]

Conbs

You might have me there.

http://www.forths.com/blog/wp-content/u ... hreads.pdf

This Honda Bulletin suggests that M10 bolts didn't change but I am just Looking at some bolts now. The M8 one appears to be the same as ISO at 1.25mm but M10 is definitely finer at 1.25mm pitch.

Standard metric is 1.5mm pitch and M10 ultrafine is M10 x 1

It looks like my little table needs updating. How about......

Thread size- new ISO - old JIS
3mm-.5-.6
4mm-.7-.75
5mm-.8-.9
6mm-1.0-1.0
8mm-1.25-1.25
10mm-1.5-1.25
12mm-1.75-1.5

If you want confusion you should check out German and Italian versions of metric......

It seems to be only us Brits who use the standard ISO threads after all those years of BSCY, BSP, BSW, BSF and BA.......

Did you know that BSP (pipe) is now an ISO standard, even though they are an Imperial size..



G

[kfsrq]

WOW! I had forgotten about the issue of pitch. Thank you all for the reminder.

I suspect that using the wrong pitch bolt to fasten the seat will not matter much.
The thread in the hole in the seat does not make many turns, so a slight discrepancy
in pitch will hardly do any harm. After all, in 47 years, the seat has been on and off
enough that plenty of wear has occurred.

But it would be a different matter if I had to replace a bolt in the engine!
I will take more care when assembling my CB77s.

I will take along some (dirty so there won't be an argument about shoplifting)
bolts and nuts of the proper thread when I go shopping for hardware.

Just make absolutely certain that the thread is proper on those lockwashers, eh? :)