Carb identification

[commando1954]

Can anyone help to sort out this issue. Bought a left carb for no 1 cyl for my k5 1975 cb750. When i got the bank of carbs off i found they were all stamped 657A ALG. The used carb is stamped 7A JA. It is identical and was sold to me as a 1971 to 1976 k1 to k6 carb. Does anyone out there know if they are the same?

[Nurse Julie]

If you look in the Gallery, I put a screen shot in there the other day for 750 carb identification. It may help you, it may not. The chances are it's the same carb body but with different main jet size fitted.

[cbxman]

Hi,

According to our US sister site, .net, the 7A carbs were fitted to the early K1 (like mine).  These bikes were made in the original 750 factory, before they moved to the "new factory" this I believe is when they changed to the 657.  However, it is my understanding that pretty much all the variants of these carbs are down to the internal configuration.  The castings look identical.  So I suggest you check the main jet emulsion tube to see if it matches your other 3 carbs (there are subtle differences, spacing and hole sizes and height on the tube), the jet needle height and of course the jet sizes.  It might be worth a check on the air bypass restrictor for the main jet emulsion tube too. (the little brass air jet pressed into the body in the intake bell)

Have fun.