carbs choices vm24 vs cv34

So i'm in project of two junk bikes into one that runs.
#1 is a '81 750cc  LTD
#2 '83 650cc CSR
It seems that the 650 has older 78/79 vm24 carbs while the 750 has cv34.

From what I can gather from kawaski.com the 83 650 csr originally from the factory the same carb (cv34) has the 750  though a few internally parts are different but with many the same part #. 

Can the older VM24 be installed on the 750cc with some larger jets? they appear to be in much better condition at this time and much less work to get cleaned up and usable.   

I am pretty sure that the 83 650 csr came stock with Miknui BS 32 carbs, but if I am wrong it would not be the first time.

yes, 83 650 csr’s used mikuni bs32’s, some 750’s used mikuni bs34’s, some used keihin cv34’s, installed 32’s on 650, which had vm24 pumpers, changing to vm’s requires replacing boots on both sides of carbs, and 24’s are probably too small for a 750, stay with 34’s 

I've rebuilt a bunch of CV34's, BS32 & BS34, VM's, most types, and honestly, all are more or less the same amount of work to get back into prime working shape.  

My 750 has CV34's and it runs flawlessly.  Starts easily, runs smooth, nothing not to like.  Key things are first, a proper airbox, with new carb boots and well sealing airbox boots.  Needless to say, a full rebuild, with all new O-rings (I have O-ring kits if interested).  And keep all jetting stock.  It will save tons of time down the road.

P1030119 by nessism , on Flickr

jwfels wrote:

yes, 83 650 csr’s used mikuni bs32’s, some 750’s used mikuni bs34’s, some used keihin cv34’s, installed 32’s on 650, which had vm24 pumpers, changing to vm’s requires replacing boots on both sides of carbs, and 24’s are probably too small for a 750, stay with 34’s 

24's are plenty big enough for a 750.
If you compare the available air flow for stock 24's on a 650  to  stock 26's on a 900/1000 then just rejet according to other engine mods if any. 
650cc
Vm24 dia = 452mm sq x 4 = 1808mm sq div by 652cc = 2.77mm sq per cc.
900cc
Vm26 dia = 531mm sq x 4 = 2124mm sq div by 902cc = 2.35mm sq per cc.
1000cc
Vm26 dia = 531mm sq x 4 = 2124mm sq div by 1015 = 2.09mm sq per cc. 

VM carbs are 100% mechanical and are simple to set up. I would run VM carbs over CV carbs everytime. 


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