I have a '79 KZ1000 LTD that I recently purchased. The bike ran good, but would not idle when cold without having to give it gas with the throttle. I took the carbs apart and cleaned them in a heated ultrasonic cleaner with simple green cleaner. They were very dirty and came out spotless inside and out after cleaning. I blew all the holes out with compressed air. I replaced the float valves and seats, but kept all of the original jets, which were removed for cleaning and reinstalled. I also replaced the fuel petcock on the tank at the same time. I did not mess with the choke assemblies, but now it seems like the choke lever will only go about half way and then jams. The bike does not even try to start now. I also set all fuel screws to 1 1/2 turns off fully seated. These are the 28mm carbs with the accelerator pump. I took one of the spark plugs out after trying to start it and they seem dry, so I think I am not getting fuel to the cylinders, but not sure why. I put in about a gallon of new gas and put the petcock on reserve so it should be getting gas. I loosened the bowl drain screws and fuel started to drip out of each one so there is fuel in the bowls. Any ideas on what to check next?
Yes I did ungang the carbs. The only thing I did not take apart was the jet needle/slide assembly. I took the first one apart and there was nothing dirty inside, so I didn't take apart the last three. I also did not set the float levels. Prior to the cleaning, at least one carb would leak gas if I left the petcock open by accident. Now they do not seem to leak at all.
Re: the vents...these are normally connected to the smog ports along with a hose from your airbox to the exhaust side of the valve cover. A lot of people have taken all of the hoses off and blocked off the ports.
I think you need to take your carbs off and open up your choke plungers to see why they are binding. If you left them in when you cleaned the carbs one or more of them may have gotten plugged with a bit of dirt. Regardless, they should move freely and easily, and if they don't they should be carefully inspected.
I also think you need to check your float levels. You should also compare your new float valves to the originals. Do they have the same number on them? If not you are probably not getting enough fuel into the bowls to start the bike. Maybe try re-installing the old float valves to see what difference that makes. And for an easy method of checking float levels...have a read of the "Wounded Zed" thread by Slmjim & Z1bebe. Towards the end there is an easy way to check floats with a glass instead of using the tube method.
I have a couple of Z1B's restored, an '80 KZ1000LTD restored, a 1981 KZ550 restored and a 2008 KLR 650 for off road fun. My wife has a 2019 Suzuki DR 650 for on and off road.
One other question, there are two brass nipples on carbs number 1 and 4. You can see the one on number 4 in the photo in post 1 between carbs 3 and 4. Is this a vacuum line? What should it hook up to?
These are vent ports to the atmosphere and should not attached to the airbox or any vaccum.
The only tubes attached to the airbox are the tube from the engine case vent and the secondary air vent tube to the smog valve cover reed valve unit.
hardrockminer has you started in the correct direction. The brass nipples should be on 2&4. Not 1&4 as you noted... as Scirocco says they are vented to atmosphere, really don’t need anything on then. Sounds like the best route would be to pull them follow hardrocks advice. Also do a bench sync before your install them. Carbs rarely work correct when a partial rebuild is done.
Edit: I’m still wondering why the throttle return spring is so stretched out. Investigate the area also
Making progress (sort of) -
* took all 4 choke plungers out and cleaned with 0000 steel wool, now working great without sticking half way - still won't run.
* replaced float valves with original valves, numbers were identical (2.3) and dimensions looked the same - still won't run.
* decided to shoot a little starter fluid in carbs to see if I could get any attempt to run - nada.
* pulled #4 spark plug to check for spark - no spark, pulled #1 spark plug - no spark.
So it looks like in pulling the tank off multiple times I must have screwed up something in the ignition. Will now start troubleshooting the no spark issue and go from there. Thanks to everyone for their suggestions! And now I am an expert at R&R of the carbs, I can do it in about 2 minutes now and not even spill any gas if I'm careful!
EDIT - I will report back here when I get the ignition sorted out and let you all know about the status of the carbs!