BRIDGESTONE AND MIKUNI THREAD SIZES

[disc_valve]

Hi, Evryone,

In response to a few recent posts on  this forum, here is a list of the thread sizes used on Bridgestone frame and engine parts, and used by Mikuni on their early VM series of carbs (as fitted to all BS models)

Note that these threads are all to the old (pre-ISO) standard, and the pitches on the smaller sizes are different to current threads


BRIDGESTONE FRAME AND ENGINE PARTS
------------------------------------------------

M2:-   2.0 * 0.4
 
M3:-   3.0 * 0.6  (ISO threads are 0.5 pitch)
 
M4:-   4.0 * 0.75  (ISO threads are 0.7 pitch)
 
M5:-   5.0 * 0.9  (ISO threads are 0.8 pitch)
 
M6:-   6.0 * 1.0

M8:-   8.0 * 1.25

M10 Fine:-   10.0 * 1.25

M10 Coarse:-   10.0 * 1.5

M12 Fine:-   12.0 * 1.25

M12 Coarse:-   12.0 * 1.5




SPEEDO AND TACHO CABLES
---------------------------------

Meter end:-  12 * 1.0

Wheel end:-  11 * 1.0  (also used on the 350GTR tacho cable engine end)




MIKUNI CARBURETTORS
---------------------------
(Note that these are all finer pitch than used elsewhere on  the bike, and in the case of Main and Pilot jets they are different from those used on current carbs)


Main Jet:- 5.3 * 0.9


Pilot Jet:- 5.0 * 0.75


Needle Jet:-6.0 * 0.75


Pilot Air Screw:- 6.0 * 0.75


Throttle Stop Screw:- 6.0 * 0.75


Cable Adjusters:- 6.0 * 0.75


Choke Cap:- 10.0 * 1.0 (On all models except late model BS350)

                   11.0 * 1.0 (late model BS350)


Float Valve:- 7.0 * 0.75 (on all models except BS350)

                   8.0 * 0.75 (early model BS350)

                   9.0 * 1.0 (late model BS350)

[moonpup]

Very nice Graham, thank you for taking the time to gather this info and posting it here for everyone's use.

That's what I love about this site, members helping members. Ask a question and not only get an answer, but much more! 

[slawsonb]

Just wanted to express my appreciation for your efforts as well Graham. Very useful. Thanks
...bert

[BRT-GTR]

Hi Graham,
               Will echo the appreciation for the list, that ones going in my BS info folder for future reference.
    I'll close my eyes while you have a quick look at the M5 pitches again-Typo.

     I did post a short list of threads myself a little while ago and said the M4 screws were 0.7 pitch but I now realise they are 0.75 as Z previously indentified. Had been fettling an early points plate with what looked like genuine original screws holding the points. These checked out with a 0.7 thread but a later plate has the 0.75 pitch. I have 3 alternators which have a random mix of 0.75 and 0.7, 4mm screws on the points plate and its cover. Probably got swapped at some time but I now agree the originals were 0.75 pitch.
       Brian.

[disc_valve]

Oops!

I washed my hands that morning and the fingers had a mind of their own!

Thanks for spotting it, Brian!

Graham

[BRT-GTR]

          Graham,
                      No, it'll be one of them dyslexic key boards, I've got one - never seems to print what I type in - gets wirse as \I get older , see what I mean    
           Brian.

[disc_valve]

|Ablosutely, Brain!

I think those little people have something to do with shuffling the keys around, too.

Graham.