Help... I want to ride!

My bike is 1978 KZ400 with vacuum keihin carbs.
It's has been sitting 6 months while I was traveling . I left the tank and carbs empty. I came home and when I started it, it ran but was very rough and would loose power on acceleration.

I noticed the oil was low and added a bit of oil, but I added too much with out realizing it. I took it for a test ride (about 1 mile) and it was still really rough. When I got home is when I noticed the oil was too high, so I drained it, put in a new filter and brand new oil.

I then added seafoam to the carbs and let them sit overnight. No change the next day. So I took out the carbs and cleaned them. one of the drain tubes was clogged. When I put them back in it ran worse and one plug was black. I took the carbs back out and did a bench sync. Put them back in and it was still running rough.

Today I took the carbs back out, cleaned them again and noticed that the Main Jet on the left side was clogged (same side that was running rich and making my plug black). I cleaned everything with carb cleaner.

I did the "clear tube" test to find the fuel float level. It was about 2mm below the gasket. The fuel float should be fine because the bike ran perfect when I left it.

I put everything back together and changed out the fuel filter for a fresh one. It still runs shitty (barely idles, seems to pop and choke, blackens plugs). I tried spraying some wd-40 around the carb boots to make sure I had no leaks and I saw no effect.

What else could it be?!?!?!?!?! Could it have to do with overfilling the oil? what else would make it run rich?

It's perfect weather and I want to ride!

Mouse or birds nest in the air filter:laugh: (yes I have seen it happen!)
Seriously, if it ran fine before and doesn,t now then if drained the carbs and tank all the carb settings should be fine. If jets are blocked you cant have emptied the carbs passages. Draining the bowls alone wont remove all the fuel from these only running it untill its runs out of fuel will do that.
All that said, if the main jets were blocked and the plugs were black it can only be a lack of air so maybe you have had residents!

Thanks Warren 3200gt: I did find some seeds in the air filter. I took it out and cleaned it all out. I also stuck my finger through the airbox and it's clear.

UPDATE: I redid the tube test with the carbs on the bike and one was over filling and leaking out the tube. I took the carbs back off and cleaned the one that was sticking. Redid the test on the bench and everything worked. Put the bike back together and it's running and holding idle. it even has good power throughout. However it's still gurgling and popping as well as blackening the plugs. so it's either running rich or maybe there is still residual oil in the pistons? it's smoking a bit as well.

Thoughts?

Have you polished the valve seats and valve needles yet?
73 and 74 on the diagram
They are what stops the fuel from flowing if the floats are set right, a little bit of crud will keep them from seating properly .

I use a Q-tip with some metal polish to do the valve seat and a cotton T-shirt for the needle , make sure that spring thingy moves in and out freely on the needles
I suggest taking the valve seats out to do this and wash them in soapy water after you are done.

Yep, I polished those and just triple checked the fuel height using the "clear tube" method and everything is good there.

I also tried removing the the air filter to see if that helped, but it didn't.

I noticed a bit of oil on one of my plugs.... So i'm thinking its oil in the cylinders from over filling it, but i don't know

How much over did you fill it ?
How many miles on the motor?

I over filled it by a quart. The bike has 11k miles on it.

I just tried the spray bottle method to see if there was any oil in the cylinders above the pistons. Basically used a spray bottle sprayer in the spark plug holes. they were dry. The bike was idling good but running shitty, now it won't maintain an idle...

Update: I noticed that the oil was way high again. Gas must have leaked through the carbs overnight when the float was stuck. I changed the oil again, hoping that this would fix the problem, but it's still running really poor.

78's have a vacuum activated petcock, unless you keep it on the middle (prime) setting it should not supply fuel to the carbs unless the bike is running.
That is a nice low mile engine but the O rings are 40 years old, hopefully you didn't do any damage .
Are you cleaning the old plugs or are testing with fresh stock NGK's?
Have you cleaned and set the points? Strobe test?
What type of oil are you using? I recommend Shell Rotella T4 15W-40

Here is an insightful write up on your bike; www.motorcyclespecs.co.za/model/kawasaki/kawasaki_z400%2078.htm

Ok, I had a thought last night. If it’s running rich and the fuel float level is correct, then it must be something else causing the problem. I dissconnected the pet coco and put a cut under it. This morning I had about a 1/4 inch of gas in the cup. I took apart and rebuilt the petcock but stretching out I the spring on the back and reshaping the wavy steel o-ring spring in the front. Just reinstalled it and I’m going to let it sit today and see if it drips. That may have been the problem.

The only other thing I can think of is that maybe one of the rubber diaphragms on the top side of the carbs dried out a cracked. I think this may cause it to run rich as well.

I put new plugs in yesterday and have been cleaning them with a wire brush to test the richness.

I rebuilt the petcock and reinstalled it. No leaks or drips after 3 hours of sitting. I reinstalled and started the bike. It ran for about 3 minutes and still seems like its running rich. Then it died and won't start again. Ugh...