Idle at 4000 after carb refurbishing

[Craigrr]

These are nc35 carbs on a nc30. The bike and I got stuck on opposite sides of the planet during Covid lockdown. By the time i got back the fuel in the carbs and tank had turned gooey and some had leaked out around failed o rings. So instead of diving right into it I procrastinated until a month ago when I started ordering parts. Litetek seal kits and keyster kits. Watched some videos, read through the manual and dove into it. Disassembled, many hours in an ultrasonic cleaner, reassembled when spotless. New carb boots. Connected to a temporary tank. Turned the key and fired right up, idling at about 2,000 with no choke and the adjustment screw backed all the way out. As it warmed up the revs slowly climbed to 4K and held. I’ve sprayed carb cleaner around the boots with no change, currently the low speed jets are 11/4 out instead of 1 5/8 also no change from 4K . If I open the choke the revs climb so I am guessing there is air coming from somewhere but the butterflies are fully closed. Thoughts anyone

[Craigrr]

So, I took the carbs off again removed the Keyster 34 slow speed jets and reinstalled the original #35 jets. Carbs back on and the bike fired up easily with choke and would idle down to about 2200. Next I took the shims out from under the new needles and tried it again. This time after warming up the idle would hold at 1800. My ear tells me it is lower but at least in the ball park.
About this time the compression tester I had ordered arrived but the adapter for this plug size did not so I used the tapered rubber tip with the guage attached to do the test. First I checked my cb400 sf to use as a baseline then the nc30. Cylinders 1,2,and 4 are similar but about 50lbs below where they should be. Cylinder 3 is about half of the others. I found early on where someone had disconnected the vacuum hose leading to the fuel tap and left the fitting uncovered; so #3 has been pulling in extra air for who knows how long running lean and hot. Next step pull the head and investigate. No need to worry about carbs until I get everything else sorted. That said I came across a good deal on a set of nc30 carbs with intact air box, but i have a feeling it will be a few weeks before I am back to the carbs

[Foxy400]

If the NC30 fuel tap set up is similar to the NC35, then perhaps there is an air leak in the fuel tap diaphragm.

My NC35 is currently fitted with NC30 carbs in an attempt to cure a problem a bit like yours. Carbs clean and shiny and set up correctly (initially by Graeme France, who generally knows what he's doing). Yet when running the revs hunt between 2000-3000rpm, sometimes more as the bike warms up, and never settle to a steady idle. I have to spend 20 mins juggling the choke and idle adjuster to bring it down closer to 1500 and even then it flutters around.
On the road the bike runs fine but at idle the problem is always there. Someone suggested the fuel tap as a possible culprit, so when I can summon the enthusiasm I'll look at changing the diaphragm(s).

[Craigrr]

That is interesting Foxy. I installed a new fuel tap and it seemed to be working fine for about a week ; but then it failed to open one day. I took it apart and torn diaphragm. I had bought the china made unit instead of OEM - I know better and am now waiting for a repair kit. A used set of nc30 carbs from a running bike should be showing up today. I am optimistic that between the diaphragm and the alternate carbs that the fuel delivery part of the equation will be sorted out. Thanks

[Foxy400]

Any progress with this? Obviously, with my bike having similar issues, I'd like to know where you're at.