Leaky carb doing my head in.

No.2 carb still leaking out of the airbox side.
I split the carbs last year (or the year before?) and had them ultrasonicly cleaned. I rebuilt them with new gaskets and new float needles and seats and I put them away for the winter.Last weekend, I fitted them on the bike and using a remote fuel feed,I got the bike started. A bit rough but that was to be expected. I was very happy that it was running on all cylinders.
 So I pulled the carbs off again and knocked together a rack to check and set the float heights. Initially measuring the heights,which were all pretty much in the area they should be,according to Clymer but when I went to check  the fuel levels with a clear tube, No.2 started leaking out the airbox side.Not a drip drip kind of leak. A flow.
Again!
 This is the whole reason that I stripped them in the first place. I was convinced that tank rust was getting into the system. Apparently not. The carbs are spotless.
So,I've been busy after work all week trying to figure out what is causing the leak. And all day today and its doing my head in.
The float itself is good,no holes or leaks. With the carbs upside down and the float bowl off,the(new) float needle and seat stop the flow. With the carbs the right way up,they don't. Swapping the needle and seat (and bowl) with one of the other (working) carbs makes no difference. It still leaks and the good carb doesn't. Bending the tab on the float to an extreme to cut the fuel off sooner makes no difference. It still leaks. Stripping it again and blowing everything through,on the off chance, makes no difference.
With the top off carbs No.1 and No.2 and the diaphrams and jet needles out, you can clearly see the fuel on No.2 flow up through the Main/Needle jet while carb No.1 behaves itself and stays dry.
It seems to me and I'll admit I'm no expert, that the float/needle/seat are all in good order but for some reason,when the carbs are flipped the right way up,something is happening to stop the float rising. The pivot pin is sitting all the way home and I don't see any signs of damage or witness marks on the inside off the bowl.
I can't see any obvious cracks or damage to the carb body itself,and like I said, when upside down,the float works perfectly and no fuel gets into the body.
This has been a long term problem that I misdiagnosed a long time ago. Any help would be greatly appreciated as I am completely stumped and have no idea where to go from here.
Thanks in advance.
(BS34s,I think. '81 KZ1000 CV carbs)

Did you use OEM Kawasaki float needles?

I had the same problem. Turned out the little spring loaded tip had a notch in it I could feel. Didn't do it all the time and when I went to check them wet it would start flooding out of nowhere. Switched it out from another set of carbs it stopped. Also if the tang is on a too steep angle it will cock the needle sideways causing it to jam and leak.  
Steve

Not sure.Its a couple of years ago. Though,3 out of 4 work fine and swapping them around makes no difference. Always No.2 that leaks.

Different carbs maybe. The only springs are the big one on the diaphram and the tiny one under the air mix screw. The angle of the tang on the float is making no difference. Set to standard height (+-) or at a more extreme angle, same result.

Might sound silly but check clearance between bowl gasket and float. They can drag on each other causing the fuel to come up the jet holder. Just a maybe..  

asphalt900 wrote:

Might sound silly but check clearance between bowl gasket and float. They can drag on each other causing the fuel to come up the jet holder. Just a maybe..  

Also worth checking the float isn't slightly bent and catching on the bowl

Wookie58 wrote:

asphalt900 wrote:

Might sound silly but check clearance between bowl gasket and float. They can drag on each other causing the fuel to come up the jet holder. Just a maybe..  

Also worth checking the float isn't slightly bent and catching on the bowl
 

I did a couple more tests this morning. There's no problems with clearance twixt the gasket and float bowl,plenty of room and the float doesn't seem bent.(If that was the problem,swapping floats should have sorted it,which it didn't). I dry tested the float this morning by stripping the bowls,floats,gaskets etc out of the other 3 carbs,leaving the leaky No.2 fully assembled,I flipped everything around a few times and could clearly hear the float lifting and dropping.So, it doesn't seem to be fouling on the inside of the bowl or on anything else. Then I  reassembled everything and with the No.2 bowl off and the carbs the right way up, I turned the fuel on and operated the float with my finger. It works fine. Float hanging loose,fuel flows. Float pushed up (lightly) flow stops.
 I then refitted No.2 bowl and turned the fuel back on. Watching through top of the carb,I could see the fuel start to come up through the needle jet,hesitate then stop!!? Fuel off, set up No.4 carb for a clear tube test,fuel on, No.2 starts leaking again. Full flow.

Vacuum petcock failure sometimes sends fuel down the vacuum line and into the carbs that way, and the vacuum line is commonly attached to carb #2.  

Having just rebuilt mine, wouldn't the small vent on the petcock leak if it were passing the diaphragm?
Unless the plastic spacer was replaced backwards or upside down somehow, i suppose. 

A simple test for this, is swap the petcock vacuum line to carb #1.

Nessism wrote:

Vacuum petcock failure sometimes sends fuel down the vacuum line and into the carbs that way, and the vacuum line is commonly attached to carb #2.  
 

Carbs aren't attached to the petcock. They're on the bench attached to a remote fuel supply BUT... good point about the vacuum situation. I have all the vacuum points blocked off but the plugs are old cracked and not fit for purpose. I was planning on replacing them when the carbs are ready to go back on the bike. Yes. You are right. No.2 is the one which takes the vacuum tube from the petcock. That might have something to do with whats going on.I'll check that out. Let you know.Thanks.

Ok. Test results were inconclusive. It was a long day at work and there was someone yakking in my ear while I was trying to check things out on the carbs but I do have all 4 vacuum ports plugged, though the plug on leaky No.2 is rotten with a split across the top. So, I have no idea if its actually plugging the port or not.I will play with it again tomorrow. Hopefully in peace and reassess the situation.
 So,a couple of questions come up. When bench testing with a remote fuel supply to the main input, should the No.2  vacuum port be plugged or be open? Should the other carbs be plugged or open? I assumed all four carbs should be plugged. Am I wrong?