Topic: Mikuni Carb swap on a stock 74 CB750K4

[1974CB750rider]

What size mikuni carbs could I put on my 74 750 K4? The bike is stock with the exception of a 4 into 1 exaust. I've seen some deals on ebay but am not sure what to buy or not to buy. A friend of mine has a 73 Z! with mikunies from the factory, but don't know what size they are. Anyone here done this before?

[MCRider]

The Z1s came with VM28 (Mikuni Smoothbore).  (I think) A common upgrade is the VM29. (Not CR) The VM 29 works well on CB750, but you have to get them with a rack for the CB750 spacing. I have used them on my CB750/888cc.

This is all I know (I think) sketchy, and may be off the mark,  and more may chime in. The VMs bring pretty good money on eBay.

PS.  I just remembered its not the rack that is different its the rubber manifolds. They are available from dynoman.com, though I don''t think he has the VM carbs. I think the VM carbs are no longer made, instead its the CR models.

Again I defer to those who may know better.

[1974CB750rider]

I found a set off of a later 70's model KZ 1000. Would that work?

[MCRider]

I found a set off of a later 70's model KZ 1000. Would that work?

I'm not an expert but I'll take up some time talking about it. First, the bore size may be too big. Carbs for a 1000cc are likely larger than your 736cc can swallow. Better to find some from a Z1 (900cc) but still could be too big. My experience has been putting them on a larger displacement with a ported head. So the carbs won't swamp the rest of the setup.

But one thing to remember, you can put any carbs on you want, if you can get "manifolds" the rubber booties to connect them up. Then its a matter of jetting them down, and hoping they aren't TOO big for your displacement.

[1974CB750rider]

Thinks for the info. The main reason I'm looking into this is I'm wanting to run K&N pods and I know it takes a lot of time to get the jetting right on the stockers. I also know that when I was younger a friend of mines dad worked on bikes a lot and one of the upgrades he always done was put a set of Mikunies on the bike. I know the Pod mod is a bit of a taboo subject on here but I rode a 73 CB350F in highschool that had them and the tuning was spot on. I saw almost 120mph on that bike and from what I read that is not supposed to happen on that bike.

[bwaller]

I believe the first three year Z1's used VM28's. These carbs are similar to the Keihins on the CB500 with the external adjusters and aren't known to hold synch well. Then they went to VM26's, on the KZ900/1000's I think until 78?? then back to an improved 28mm with a pump.

The early VM28mm command big prices but the VM26 are a dime a dozen, I'm not sure these will do much for your 750. They have a full round venturi nearer 27mm in size. However 29mm smoothbores would be the bees knees except these are very rare too.

As MCRider mentions Dynoman has the intake manifiolds for the conversion.

Top are the early VM28 with the center drain, next are the VM26.