Can't decide what carbs to use

I just think it is easier to jet the carbs without the pumps.

I don't like all the extra plumbing on the carb bowls.


What is a good set worth timebomb? :laugh:

If you read my signature, you'll see I'm running almost the exact same setup as you are proposing. While I lost a bit of mid range torque with the 34 flatslides, I was able to tune most of it back while gaining decent overall performance, especially on top. While you can't really just whack the throttle wide open, I've got the pumps tuned to where I can roll them on very quickly without any hesitation or blow back.

If you go with flatslides let me know. I'll give you my jetting specs.

BS34s baby Thats why Kawasaki used them from 82 to 2005 ..With the right set up they out perform the 29mms.. Yeah Man

Yes, but the 34CVs are quite a different animal from the 34 flatslides that TerryK is talking about.

no doubt

TexasKZ wrote:

Yes, but the 34CVs are quite a different animal from the 34 flatslides that TerryK is talking about.

Exactly. I tried CVs before and I didn't the "softness" of them. They made good torque though.

Years ago i asked why the drag guys used the BS34'S.

The answers i got was they were constant.

I'm talking bracket racers.

I think cost was a consideration here. Roy

All pretty good points...

The BS34's can be a bit of a PITA to tune. They can have near the throttle response of the 28s', but it generally takes lots of "tinker time" to get there. They will produce more HP. They are a bit touchy at slow speeds when tweaked for better a response. + If your using pods, its highly recommended to use a jetting kit to prevent flat spots, as a these CV carbs require changes to the air jets/passages as well.

The 28s' are a good choice for jetting pods. Fairly easy to work with, and a plethora of info on them here. Despite my love for the 34s', the 28s' are smoother at slow, even when tweaked out. They will have plenty to give thru to about 1/2 throttle pulls, then the 34s' size advantage would take over.

For me, BS34's for sure. For you maybe the 28's for now...

Save the extra cost of a BS34 jetkit, if going with pods.

:laugh: OR DISH OUT THE DOLLARZ! :laugh:

Cheers.

in the plumbing world going from a 34mm pipe to a 26-28mm pipe would be referred to as funneling which aint a good thing on drainage pipe,and that is using a transition fitting to make it a gradual change in size.what youre thinking about is more like trying to suck jello from a 5 gallon bucket using a straw,which really doesnt work well.kinda like running a rectangular port intake on a bigblock chevy with oval port heads,that dont work either! :S id say run the 28s or if you can afford it a set of 29-31 crs like omr is talking about.

Old Man Rock wrote:

I'm with Steve on this one, 28's over the 34's...

Reasoning, unless mid range to WOT, the 34's won't respond at lower ranges like the 28's will...

Now, if your going to pay for carbs, let's say ~ $500 then save another $200 and go with the Keihin 29 or 31mm CR Specials...

From two different reliable sources, pending your riding style, 1075cc/performance cams/valve P&P or smaller go with the 29mm setup... 31mm maybe in your build but anything larger, why bother.

Low to Mid blows you away.... Pulls like a mo-foe.... Hell, nearly pulls me off the seat... It's crazy I tell ya....

Are they expensive, yes indeed but.... New technology, phenomenal performance, easy to jet... so you get what you pay for....

Just my worthless 2 cents worth....

OMR

Allright I'm getting tired of hearing this STUFF. I've never had a set of cv's hesitate whatsoever, unless the airbox was off or jetting wrong. WTF are u guys TALKING about? Those carbs are quick! Instant! Right now! Whack or no whack. And if u look at the power increase the z motor had when it ended up with cv's finally, you'll note that it's increase is coming from the fact they took off the vm's and put on cv's. Now. Whats so hard to understand folks? Why hasn't anyone told about this fact? Do you guys even really know how these carbs work, since your so busy playing with other ones? No mystery here. :woohoo:

Big blocks, funnels, plummers, more money eithers or's and such. Royal nonesuch. Cv carbs out pull, out dyno tune, outsmart, litterly outset vm 28's all day long ev. day. Ask Larry 'c what happens when the dyno talks on this issue? Only prob is when u whack the throttle, the bike bogs and the front drops down proceeding are two consecutive front rolls. Never seen it hap, but been hearing stories. We need a couple of kz myth busters. Couple new ones anyhow.

I doubt very seriously that a 28cv will produce more power than a 28 smoothbore or flatslide. Of course a 34cv makes more power than a 28 sb, a 34mm venturi flows more than a 28mm venturi. The larger the venturi, the more maximum power the engine will produce until the carb out flows the port/cam combo. One of the big problems with big carbs is low and mid-rpm performance. In an extreme case, a huge carb whacked open at low rpm will cause the engine to bog or even die. The cv design is an attempt to overcome the big carb - low speed problems. Since the slide in a cv carb is opened by atmospheric pressure rather than by a mechanical linkage, the velocity of the air across the venturi is constant no matter the throttle opening or rpm. This prevents bog at low speed, but creates a softer throttle response than with a mechanically operated slide. This is why muscle and pony cars had vacuum operated secondaries in their 4bbl carbs, at least for street use.