Alternative to my BS34's.

I have a PSP modified motor. Punched to 1075, PSP's 3X cams (andrews grind), stage II porting. The valve overlap is such that above 3500 rpm it comes alive, pulls like a freight train. But because of the greater valve overlap and the reduced vacuum at low rpm it suffers down there. I've played with the pilot jet and idle-air screw but I don't think I'm ever going to get a CV type carb to work at low rpm with this motor package. Suggestions?

Mikuni RS34's is what I went with. Just be aware the RS stands for Rattle Slides. There is a noticeable noise at Idle from the slides. But tune ability and cost/ range of jets is good. I still run the stock airbox.
There are a few posts from other guy's running CV style carbs but from another application. So as the tuning is closer to the change in engine set up. They have posted good results.
There is the Mikuni 29&33 smoothbores, and Keihin CR's out there as well.

I too have a modded engine, GPz1100 with the MTC 1135 kit, ported heads but with the stock cams, 4 into 1 pipe and K&N pod filters. After about a year and lots of $$$ in jets and needles for the BS34's I gave up and went with the Mikuni RS36's. Once I got the RS34's tuned, (which took a LOT less time) I am VERY happy with the performance from idle to WOT. Starts right up, idles nice and smooth, pulls hard anywhere in the RPM range. I also love the rattling slides at idle, sounds really cool. I have had really good luck tuning the BS34's with a 4 into 1 pipe and pod filters on stock engines but once you start changing the vacumm signals with porting and cams you will never be able to tune those carbs to work correctly.

Go with the new RS carbs if you can afford them. The old 29s & 33s will cost yuu almost as much and you never know what youre getting. I run 29s on mine but I wouldnt pay what they want for them now

Appreciate the feedback. Believe me, I would love to keep the BS's if I could fix just one thing. All of last year I lost riding due to some shortened advancer springs. (Think my engine builder thought I was going to drag race)LOL. So I struggled down low, the springs were so stiff it wouldn't advance without babying the crap out of the throttle, building enough rpm for it to advance. My IC Ignitor died but that gave me reason to install a Dyna S system which works so nice. So this year, with a new oem advancer I am able to ride. Still had issues down low and worked with WG on jetting changes. Discovered I was only getting 9 vdc to my coils, did the auto relay upgrade, got a good 12 vdc to the coils now, even with the fatter spark still issues down low. I've got about 600 miles on the build and this much I know for certain - in any gear at 3000 rpm if I roll on the throttle it bucks and lurches. Now, in any gear at 3500 if I roll on the throttle it's perfect, all the way to redline. Smooth and strong. So what's happening? Has to be something with not advancing and being fully advanced. Manual says motor is fully advanced at 3400. I believe that, I can feel when it is. Let me go back and say to fix a detonation issue I had I have retarded the timing 6 degrees. Factory has me at 10 degrees at idle and 40 fully advanced. PSP said I should be at a minimum 36 degrees when fully advanced. So, my question is can I be too retarded and that's effecting my below 3000 rpm issue? Too retarded. That didn't sound right.

Jut put a big-azzed sprocket on the rear and you'll be riding past that 3500 rpm range in no time.

That is the exact same RPM range that my BS34's carbs gave me trouble with. 3000 to 3500 range mine would buck and miss really bad until it got above 3500 then ran fine. It would start right up and idled good but right off throttle it would have huge dead spot.
It would also have a hanging idle whenever I would blip the throttle it would hang come down really slow, took about 20 seconds for it to return to idle. I was unable to tune those two of problems away. If you are going to stick with the BS34's all I can tell you is good luck and if you do find the solution let me know.
And no, your problem is not going to be the advancer. I too played with the advance, lighter springs, stock springs and stiff springs. The only difference I could feel changing the spring stiffness was when the springs were to light. The idle would never come down as soon as I got on the throttle the advance would go to full and the idle would stay high until I turned the engine off. With stock and stiff springs I could not tell the difference between the two.

1075cc 3x cams, 29-31mm will work out nicely at lower rpms...

Wish the MIK's came in 32mm for 34mm just a tadd too large for my build, reason I went with Kehins...
In either case, beautiful racing carbs, easy to jet and fine tune for performance.

Well, I was afraid I was going to hear that baldy. I'm sure there are those that would argue that it can be done but I think my research has concluded that I would follow the same path you took only to arrive where you are now with the RS's or something equivalent. In your post you mention the RS34 and RS36. Which one do you have?I have OMR's recommendation for the CR29 or CR31, what would be yours? Factory air box or pods with these types?

I am running the RS36, I chose those because I am right on edge of the engine being to large for the RS34's, 1135cc. The RS34 are good to about 1200cc. I will be doing additional work on my engine so I didn't want to have to buy a bigger set later. The 36's work fantastic I am sure I'm giving away some low end torque with the 36's but the bike pulls so hard now I really can't feel it.
The CR's are also great carbs, the reason I did not go with them was when I was looking they were back ordered for a long time and I did not want to wait. If I was you and not going to go any larger with the engine or adding additional performance parts. I would go with the CR31's if you can find them at a decent price however the RS34's are usually cheaper and easier to come by. You will be happy with either one. You will have a very difficult time trying to get you stock airbox to fit either the Mikuni's Or Keihen's, they were not designed to run with stock airboxes. I would just with the pod filters. Also they are pretty much jetted correctly right out of the box. I could have run my 36's the way they came out of the box but I am really anal and wanted it perfect.

Baldy - going with the RS34's. Did you have any detonation issues with your build and if so, how did you address them? I'm hoping I can keep the timing retarded 6 degrees, which fixed my detonation problem but screws up the low end, and address the low end with the new carbs.

Once you put a well tuned rack of performance carburetors on a well built engine, you will be nicely surprised at how much stronger they pull over CV carburetors. If it were me, I'd blow right past the RS34's and put RS36's on it.

We went down that road with CV carburetors and performance cams 25 years ago. They are just not a good combination for all around performance. A carburetor needs to be sized to deliver the air the engine requires but equally important is their ability to deliver the correct mixture curve over a wide RPM range.

The Keihin CVK was a much better carburetor than the Mikuni BS at delivering a good fuel curve and dam near equaled an RS34 for drag strip performance.