KZ400 VM32 Conversion

I've been fighting this for several months now and decided to pass it on to the experts. 

Problem: The bike idles at 3500-4000 rpm. I've tracked it to one of the carbs, when I switch the carb from side to side the high idle follows it. The boots are new, the ignition system is new, the engine was just rebuilt and ALL seals are new. The carbs were boiled in lemon juice/vinegar after careful hand cleaning (there is 0 dirt in them), this made it run better but didn't solve the idle problem. All the carb gaskets are fresh and all the jets/needles are new but the carbs themselves are second hand. I have sprayed everything with pb blaster to check for air leaks and couldn't find any. Pulls almost as hard as my yz400f and there aren't any holes so I'm pretty happy with the jetting, only issue is the idle. Is there anything i can look for on the bad carb that may be causing this? 

Any info would be a huge help, i really just want to ride it.
Thanks.

Bike info:
-75 KZ 400
-ported cylinder head,
-head milled for compression (10.5 ish),
-2 into 1 "open header" (loud as hell)
-Uni foam pods
-Dual Mikuni VM 32 carbs 
-25 pilot
-210 main
-6f5 needle
-clip position?
        -2.5 slide  

1] carbs are to big
2] they are jetted like a 2 stroke


.

1.] Yes the carbs are big...maybe too big. This was done intentionally to support the ported head/exhaust and a web camshaft in the future. Research suggests there are other people running these carbs on less modified engines with success, that doesn't mean its correct its just a data point. Given that the bike feels like its going to wheelie when i get on it, this leds me to believe the sizing isn't too far off. the bike might be even better with small carbs though.
2.] Jetting is similar to all other kz400/440s running vm32s not sure why they like the mains so big but they do. The plugs look great. There is power everywhere, even cruising around under load at a 'normal' idle speed.

Let me restate my problem. ONLY ONE CYLINDER is running high at idle. This is caused by ONE of the two carbs because when i switch the carbs around the problem follows the 'bad carb'. When I progressively apply the choke to the 'bad carb' the idle returns to a normal 1000-1500 rpm but the cylinder starts misfiring and coughing on the fuel. I was thinking there might be a crack or some other defect on the carb. Thanks for the replies.

Your idle circuit is lean on that carb.
The reason the jetting is so big is because the ventri effect/signal is weak. The air velocity thru a big carb feeding a small displacement cylinder will be lazy. A larger jet will be needed to 'pull' the fuel required. On a 2 stroke there is less time to get the air and fuel into the cylinder. 2 stroke carbs have larger needle jets to accomplish this. A big 2 stroke carb on a small 4 stroke is going to need large jets.

Have the carbs been properly synchronized? Fuel levels checked?

Bike needs some mufflers too.  Too much flow on both sides of the engine.

I set the float level with a caliper to insure both carbs were the same. The tangs are parallel with the bowl gasket. The carbs were synced with a drill bit, I don't remember seeing any vacuum ports on the head. I have plans to make some through the carb bodies or boots once I have access to a machine shop again. 

I don't see any reason to put a muffler on at this time although I'd eventually like to buy something nicer, right now Hagon shocks are higher up on the list. The primary tubes are the same diameter as stock and similar in length to the commercial 2 into 1 systems so I doubt the scavenging is messed up. I also don't see how that could cause one cylinder to idle fast while the other is fine.

I plan on experimenting with a 27.5 pilot on that side. 

Setting the float height is a good preliminary step, but the actual fuel level should be confirmed via the clear tube method.
Likewise, setting the slide openings on the bench is a good start, but they should be fine tuned with vacuum guages, or other appropriate tool. Don't the VM carbs have a vacuum port? Maybe I am old and forgetful, but I thought they each have a fuel inlet, a bowl vent and a vacuum port.
Are you certain that both throttle cables are releasing properly? Perhaps one is hanging up.

So you are going to change the pilot in one carb? They should be the same unless something is seriously screwed up.

Agree.  Do not bump pilot on one side.  The jet size is not the problem.  You most likely have an air leak, and spraying stuff on the carbs doesn't always find vacuum leaks.

Are they real Mikuni, or Chinese knockoffs?  You might simply have a defective carb with a crack somewhere or a leak from a casting void.

My buddy ordered a Weber performance carb for his son's Toyota Celica, but he couldn't get it to idle right.  When he brought it to me to checkout, I found an 1/8th inch hole in the sidewall of the carb leading straight into the throat.  It was a casting flaw.  When he called the supplier, the supplier seemed to be aware of the problem and sent him a new one.  The funny thing is, the supplier and I both agreed that it should not have affected the idle since it was above the throttle plate.  But if there is that major of a flaw in the body, who knows what other flaws there might be.  They sent him an upgrade carb at no additional cost, and that one seemed to run great out of the box.

The carbs are real but they are second hand, likely off an old 2 stroke snowmobile. I went over them thoroughly and didn't see any cracks but its possible I missed one. They are completely clean with new gaskets and brass (besides the air jets although they were the same). Any suggestions for finding an air leak besides spraying crap on the carbs? Only thing I can think of is getting a cigar and blowing smoke near the carbs.

I have 27.5 pilots on order. I plan on trying both of them first and if it causes fueling issues in the good cylinder I will try a combination of the 25 and 27.5. I'm not real worried about running 2 different pilots. Its possible my carbs were manufactured at different times and the tooling could have been different although they look identical.  

Thanks