Topic: 1978 CB750 K Carbs Carbs & more Carb confirmation needed.

[Airborne 82nd]

 First thanks for all the help so far from everyone As the title says my bike is a 78 750K the carbs are 42b with 35 slow & 110 mains the bike runs great has stock intake paper filter from Honda plus I have a spare K&N that I may or may not use depending on what the most and smartest say. The exhaust is a 4 into 2 unknown brand so one on each side they have baffles and sound good a little deeper throatier than stock.
  I bought a complete rack for $50 that are very clean on the outside and the bowl area. I am still going to break them down to make sure they are good to go on the inside. Now the questions The new set are 42a. I have read the bodies are the same. Is this true? If so can I just change the high & low jets? I think the lows are the same #35 but not 100% sure. Also is the float height (12.5 +/-.5) or (14.5 +/- .5) I cleaned the set on the bike (PD42b) a few months ago and got them right on the third  try Like I said it runs great all clean. Choke and fast idle cam set float height  but I not sure if I set them to 12.5 or 14.5 but at the time I use the clear tube and they were all about 2 to 3 mm below the bowl gasket.
  Just to recap what is the correct carbs on a 78 750K? What slow and high jets are correct? What is the correct float height? Should I start with the pilot screw 1-1.5 out from a gentle seat? If I have forgotten any thing please let me know. I take corrective criticism very well. Any little tips are welcomed.

[750K]

Whats wrong with your current set?

[Airborne 82nd]

Whats wrong with your current set?

Nothing I just wanted a extra backup and do not want to take the ones off the bike to see what I put in them and lost my notes in shipping. Notes are in a box some where. I'm not sure if my extra set is the same being they are 42a instead of 42b. I think the A's are from a F model. I like to gather spare parts when I can. Mainly is the (A bodies) the same as the (B bodies). I did take the bowls off the spare rack today and they appear to have been set up for pods 120 mains.

[750K]

I'm pretty sure the a and b bodys are the same, I switched from a's to b's last year. B bodies with all the internals of the a's, I went from 41a's to 42b's iirc. 77k to 78k carbs and the only real difference in mine were the atmospheric vent system and the 77 needles are adjustable where the 78 needles you have to shim to raise. The rest of the internal components are interchangeable, your manual will have the idle mixture & float height specs as well as stock jet sizes which are 35 & 110 iirc.

[Airborne 82nd]

I'm pretty sure the a and b bodys are the same, I switched from a's to b's last year. B bodies with all the internals of the a's, I went from 41a's to 42b's iirc. 77k to 78k carbs and the only real difference in mine were the atmospheric vent system and the 77 needles are adjustable where the 78 needles you have to shim to raise. The rest of the internal components are interchangeable, your manual will have the idle mixture & float height specs as well as stock jet sizes which are 35 & 110 iirc.

Thanks just what I needed to know I was not sure about the bodies I did find the specs in the manual. So all I really need to do is clean and put the correct jets in check floats bench sync.

[750K]

Yeah you should be good to go.