Hey guys i have a 23 briggs with a mikuni and I'm having trouble getting my jetting right. Carb stutters bad from slow speed when I stab the throttle. Worse than my stock carb ever did. With thes Mkunis it it possible to hammer the gas from idle with out it stalling out.
I have a
35 pilot
6f5 needle 2nd from top position
175 main
2.0 air jet
air screw 7/8-1 turn out
Runs awesome on top end and idle, sucks in the midrange and under hard acceleration.
I have a cam, bps pipe, polished stock intake and rev kit in it. Rest is stock.
runnin at about 800 ft elevation and 80-90 degree weather right now.

Is this similar jetting to what you guys have or do I have a jank carb?

What type of mikuni ? (I don't recognize the part designations you note). Where did you get the carb (i.e. what was it set for before?)
Do you have a mikuni tuning manual for you carb (you can access on-line)?

Its a mikuni vm 34 roundslide from BPS. I've been using my tuning manual but just can't seem to get it right. I'm thinkin I may have a wrong sized needle,jet or something.

What is your idle rpms set at? If its to low it will stall some what when hammering on the throttle. Not sure on the 34 but 1150 to 1200 rpms seem to works the best on the 42 HSR. I personally have my idle set at 900 but I let it build up to at least 1150 to 1200 before racking her back. It sounds like your air pilot screw needs adjusting or the pilot jet might be a bit over sized.

Flat spot is not going to go away with that carb. Your jets are too big as well.

I have a 30 pilot I can put in. Is my needle and main jet to large also. I have it idleing at 1100 rpms now. I'll raise my idle to 1200 and lean my pilot out. Do you guys think my main is too big? Thanks for the ideas so far.

Ended up getting a bum mikuni. Got sent out with a totally mis-matched needle jet and needle. Runs really good for the most part now except today I noticed it was slightly faster at about 3/4 or 7/8 throttle than it was at wot. Been trying to figure out if my main is too rich or too lean. My plugs are i'd say dark brown. I've read on the internet from different sources it could be lean and some say too rich.

Currently I've got a 175 main
needle 2nd from top
30 pilot jet
air screw 1 turn out.

What you guys run on 23's for jet sizes? A baseline from someone would really help. thanks

Your too rich if you lose RPMs at full throttle, its not burning the extra fuel being put too it.drop it to a 165,170

Thanks gator guy I will give that a try.