Idle trouble with stock BS34 Mikuni CV carburetors (also broken bits)

[JaxShane650]

The Bike
I have a pretty much stock 1980 xs650 that I am trying to get back into road worthy condition. I have pretty much got this thing ready to go but I am having a carburetor issue(or at least that what I think is the issue). The carb is a BS34 Mikuni and I have no clue if the main jets have been enlarged.
The Problem
When I first start up the bike I have to run it on choke for awhile before it is able to run on its own, and there is no throttle response until it is warmed up. If I do try to throttle it while it's warming up, it most likely stumbles and the carbs make a hissing noise and the bike tries to die and every now and then there will be a backfire. Once the bike warms up though the idle will smooth out, but it seems to idle pretty low considering the idle adjustment screw is turned all the way in. Then when I hit the throttle when it is warmed up it will really hesitate and be at low RPMs until about 2000 RPMs, then it picks up and I get full power with some backfires sometimes. Also I have noticed, with the filters off,that the slides in the carb do not go up and down when the RPMs go up to max or down to idle. I'm somewhat new to motorcycle carbs and was wondering if they are supposed to go up or down at all? Could that be part of the problem?
What I Have Tried
So when I first got the bike I did a almost complete rebuild and cleaning of the fuel system, including the carbs. Now when I took them apart I cleaned them to the best of my ability and made sure everything was in working condition and checked the slides(including the diaphragms) and noticed that they were in good condition. Then I put the carbs back on the bike with a new pair of gaskets and boots. The problem started as soon as I started the bike after I got it all together. So before I tried to adjust the fuel mixture (because I thought that might be the problem) I tested the compression which was great (150psi), checked timing chain tension which was good, checked valve clearance which was good, checked the spark plugs and they look good, and then checked the timing whcih was spot on. So I know I am dealing with a crab issue and I go to adjust the fuel mixture. Then I proceed do what a post on here recommended, which was disconnecting the spark plug on the opposite side you are tuning (just to be safe though I connected up a spark plug to the unhooked wire and grounded it to the bike). So I tune the right side carb with the fuel mixture screw and it goes pretty good its running pretty well on this one cylinder. So I switch sides to the left carb and disconnect the the right cylinder spark plug. When I do this, I notice it takes a lot of choke and throttle to get the left side running at all, and adjusting the idle screw does practically nothing. So this whole time on idle it has been running on one cylinder practically and the left side doesn't kick in till high RPMs.
What To Do Next?
So I'm at a dead end here and don't know what to do, any suggestions, videos, or links to similar threads that would help me alleviate this problem would be more than welcomed!

 

[retiredgentleman]

The pilot circuit in your carbs is not delivering enough fuel/air mixture. The usual problem is total or partial blockage in the pilot jets, because they are a very small orifice.. I suggest you go the Tech section and find the Carb Guide for CV carbs. Read it through a few times, and focus on the pilot circuit passage ways, mixture screw, etc. When you had the carbs apart you should have recorded what size the jets are. Was the rubber plug in position over the pilot jets? Did you remove the jets to inspect them when you did the carb work?

 

[JaxShane650]

Yeah I figured I'm going to have to tear the carbs back apart and look at the idle circuit, I was just making sure it wouldn't be anything else like the cv slides or anything. When I first cleaned them and tore them apart I took out and cleaned the main jets all the way through but didn't really know what to do with the idle circuit. I got new plugs for the pilot jets and replaced the old one with the new. How do I record the size of the jets? I'm guessing with a caliper in some way?

 

[retiredgentleman]

The main and pilot jets have a number stamped on the side. Its small but its there. If you have changed the air filters and/or the exhaust from the stock parts, then jets would likely have to be changed from the stock size jets. The Carb Guide has a table that shows the stock size of jets for all years.

A word of caution. When you go to remove jets, you must have a screwdriver with a tip that is the exact fit into the slot in the jet. If you try to use a screwdriver with a sloppy fit, you may strip the brass slot. When replacing jets, use only minimum amount of torque on the screwdriver as you seat them.

 

[5twins]

Here is a stock main jet. You can clearly see the size number (132.5) stamped on the top. There is also the letter "R" and the trademark Mikuni "square in square" emblem .....

All genuine Mikuni jets will have this trademark emblem stamped on them somewhere .....

The heads of the pilot jets are too small to stamp anything on so you will find the markings on their sides .....

 

[JaxShane650]

Okay so I did some tearing apart, cleaning, and investigating of these minikuni carbs. From what I found these carbs seem to be completely stock when comparing them to the pictures 5twins posted. And you all were right about idle circuit being most likely dirty, there was some dirt in the circuit that I believe caused the idling issue.
Here are the Idle jets

Idle jets that are in the throat of the carb by the air filter

Main jets (too worn out to see the marking but I believe they are stock)

Here are the slides

Before I put this thing back together I was thinking about re-jetting this carb with this kit for the BS34's https://www.mikesxs.net/parts/yamaha-xs650-dyno-tune-needle-jet-kit-for-bs-34 from MikesXS and wondering if it they are worth it since this kit says it helps with aftermarket filters and exhaust which I have on this bike.
Here are the Carbs Themselves

and while taking them apart I stumbled upon a problem I tried to solve before I took them apart for this second time. The problem being that one of the posts that holds the float in place had sheered off which you can see here.

I have tried and used JB wield to put it back together and and thought it would work but it has not survived the gas and fell apart when I opened up the carbs. Any of you experts out there have a solution for this problem or some compound that will withstand gas better than JB wield does?
Thank for all the help!

 

[Tully]

Hello I can see that this is an older post but were you able to get your carbs cleaned enough to get your bike back in order?

 

[JaxShane650]

Hello I can see that this is an older post but were you able to get your carbs cleaned enough to get your bike back in order?

Yes I was able to get the them fixed, back together, and got it running pretty relibly. Only problem I ran into afterwards was a slight stumble in acceleration in the mid range, due to the jets I'm using I believe. I think I made another post about it but I'd have to do some digging.