Engine/Carburetion Problems

Hi! I am a year into my build of a 1975KZ400 build (with a 1976 engine... Long story) and ran across a problem that I was hoping someone could help me figure out. First off, I am using a pair of Mikuni VM30 carburetors as when I bought the bike, it did not have any carburetors at all. I bought them from speed motoco, but had problems and then tried to match the jetting to the ones that dime city cycles sells (25 pilot and 140 main). As of yesterday, I can get the bike to fire up when on choke, but it does so screaming at 6,500 RPMs. When I turn off one choke it drops and when I turn off the second, the bike dies altogether. It will not start without the choke. Would any of you have a suggestion as to where a good point in troubleshooting this problem might be? Thank you for your suggestions.

What sort of air filter are you using?

The carburetors came with UNI pod filters. I had used them in the past, but with this second engine that I just put in, I was starting it with no filters to see if it was running. Might putting the filters on impact the way that it runs? Also, thank you for responding. I appreciate it.

Yes with no air filter it will be way lean and require the choke / entricher. I would suggest you put the pods on.

Thank you again for your response. I did put on the filters and it did seem to lower the choke-on RPMs by about 1000 or 1500 (Instead of running at 6500 RPMs, it ran between 5000 and 5500 RPMs). You mentioned that not using the filters would cause a lean operating environment, so I changed out some pilot jet sizes (I don't know why this was what I decided to do, but I was trying to get more fuel in to make it richer - as a novice to mechanical things, I don't know if it makes sense). I went from a 25 to a 30 to a 35. With each of these changes, the RPMs of the bike with the choke on seemed to rise... after using the 35 pilot jet, it was back to running even more quickly. I don't know whether this has anything to do with the pilot jets or whether it is because I changed them out somewhat quickly and the engine was getting warmer. It still does not want to fire up or run with the choke off... When I turn the each of the chokes off, the respective cylinder shuts off. Thank you for any suggestions.

I have mikuni's on my 79 750..there is no choke for say..the socalled choke opens a passage to fuel bowl and allows raw fuel to be sucked into the cylinder ...... Just guessing possiable pluged fuel passage??????