BING Carb questions for 1969 125cc Steel Tanker

[t20sl]

I have the original Bing 26mm for my 1969 Six Days.  It has a 120 main.  The number on the Bing is 1/26/117.  Both carbs look identical except bore. I also have a Bing off of a Penton 1971 125 steel tanker.  However the number on it is 1/27/17.  What do these numbers stand for?  I know the 26 / 27 is the Dia but what do the last 2 or 3 digits stand for?  Also what jetting should be in the 26mm?  120 or 140.  I have seen manuals showing both.  Both these carbs have the drilled jet needle holder as per a Penton service bulletin.  I will probably error on the rich side but thought one of you early steel tankers would know which is correct for jetting.  

Thanks, Ted

[john durrill]

Tom,
 I think the last number gives the options the carb has. Like
style choke, which side the fuel inlet is on , which side the idle adjustment screw is on, style needle jet holder,spigot or clamp on mount etc.......
John D.

[Doug Wilford]

Ted;
I am not sure what the last set of numbers mean.   I always thought it was a model number.   I am sure if you use the 130 main and 35 idle even a 135 main in the 27 carb.  you will be able to get the performance you want from either of the carbs.
Have fun!

[Kip Kern]

If memory serves me correctly those #'s are the specific jetting for that particular carb.  To be sure contact "Bing International", they can give you the exact info you need plus tell you what carb fits what machine by the exact numbers.