i havn't a clue ---- again

[berger]

hello you lovely peeps it is now santa time MERRY CHRISTMAS to all our readers [ humbug ]  so here goes , my yonda CB750FZ 1979 is fitted with keihin VB52A carbs, the two manuals I have don't cover the FZ which is a originally a Japanese market bike. the books which are for 1978 to 1984 models says the CB750F is fitted with a VB42A or a VB42B and the CB900F with a VB51A. so what is the difference between a VB42A    VB42B     VB51A and VB52A which is on the bike , I know nothing except santa has burned his bum and b*gg**d off

[muskrat]

G'day Bergs.
Basically it's venturi size then there's jet size, accel pump, etc. It's a bit of a mine field knowing which one goes on which bike. My book says for my 83 CB1000F is VB56A but it has VB57C!
Different countries had different carbs. My 81 CB750FZ had 42's, no accel pump but adjustable pilots (US had covered pilots)
VB41 or 42 is for your bike with a choke size of 32mm. The 51 or 52 is for the 900/1100 with a choke size of 33mm. Do your carbs have an excel pump on #2?
https://motorcycleproject.com/text/specs_revised.html
The good thing with CV carbs is their not affected by altitude so going from sea level to 10,000ft there's no need to change jets.
One piece of advise I can offer is DO NOT replace the std air box with pods. I know it's a pita getting the carbs on and off but It won't work.
The other prob with these carbs is the seat for the float needle. They are pressed in so replacing them is a real pita. Just did mine. New floats, needles & seats. The float height is governed by how far their pushed in. A few thou too far and the float height is too rich. The book says 15.5 mm but to get it to run right I had to use 17mm.
Cheers

[berger]

cheers musky, I have no intention of using pods. I will study things a bit more closely and look at the link you have so kindly found. I hope to report back to let you know what I find out