TOPIC:

1983 KZ1100.
After riding the bike and putting it away, when I go to get it out again, I tilt it up off the sidestand and fuel drains out of the airbox, creating a small puddle on the floor. I see what appears to be a nipple in the middle of the box on the bottom, which has a nipple on it for what probably should be a drain hose. The hole in the box for the nipple is not clogged, but is wet.
I did have a poor seal on the carb holder on one of the cylinders which I snugged up best I could. (new ones are in the plan). It is not leaking fluid out of the seal now. But the fuel in the aibox issue repeated after I rode it again.
My question is what might be the reason for the fuel in the airbox? Would a poor seal on the carb holders be a cause?
The bike starts, idles, and runs fine.

The carb is over flowing and draining into the airbox as designed. Bad needle/seat, float too high, or any other reason that the fuel would be overflowing the bowl

Thanks for the reply, that makes sense.

Would also check the crankcase oil to determine whether the oil has been contaminated by gasoline having entered the crankcase and mixed with the oil. This is because gasoline rising into the carb throat can also flow forward toward the engine ( not just backward toward the air box) and go through the intake port, into the combustion chamber, and down past the pistons and rings into the crank case.

Good Fortune!

The oil did look a bit fuller when I tipped it up to check the site glass before my ride.
I think it is time to park it and put some time and money into the old girl.
Can anybody suggest good carb rebuild kits?

No rebuild kits needed, take them apart, clean them really good then set the float levels using the wet method. Of the several hundred carbs I've rebuilt over the last 45 years very rarely did I have to buy new pieces. I even used the old bowl gaskets. For the needle and seats I use "Brasso" and a Q-tip to polish the seat.
I don't like the "rebuild kits" because they are not Mikuni parts and as such the jets and needles are not held to the same quality specs as Mikuni.

Ok. I just took the bowl off the carb that was leaking out of the carb holder. It is not stopping the flow completely when I push the float up. It has a drip.