TOPIC:

Maybe there is some confusion about terminology. You said there is a vacuum line that used to connect to the filter box, but is now just lying around. A vacuum line provides vacuum (low or negative pressure) to a device, such as the fuel valve, in order to do work. If the line is no longer connected to a device, it must be plugged, else it will introduce unmetered air into the carburetor, completely screwing up the mixture. No amount of adjusting can compensate for that.
A vent hose is used to balance pressure between a device and the atmosphere. A hose from the carburetor fuel bowl is such. A vent hose must not be plugged.
Some carburetors have overflow tubes. They drain excess fuel from the float bowls when there is a failure of a float valve or if the float is wildly out of adjustment. Such a hose must remain unplugged, else all that fuel will run into the engine, possibly causing damage.
Drain hoses are for draining the bowls, and are connected to a drain screw that is normally closed. The other end of the hose should be open.

Vacuum ports are typically located very high in the carburetor, and it would be nearly impossible to force fuel out of one. If you were blowing into a drain hose (after opening the drain screw) and fuel was coming out another hose, it was likely a bowl bent or overflow hose, depending on which carburetors are on the bike.

Does the bike have a vacuum operated petcock? If so, the diaphragm may be cracked and leaking fuel into the carburetor that the vacuum hose is connected to, causing the problem you describe. It is usually connected to number two.

Getting the hoses properly sorted is necessary to proper carburetor function.

apologies yes im confusion terms. 

so the drain screw on the bowls is closed. 100%. the hoses out the bottom of the bowls are drain hoses to the best of my knowledge, so when i blow into them, the air comes out of the hose (not vacuum line as its blocked off) from the carb that I believe is just an air hose for the carb. I ran it up under the seat. there are two of them. The bike used to have a vacuum petcock but it does not now, just a regular one so i have blocked the vacuum port off on the carbs. It ran this way perfectly up until now, so I doubt the hoses are bad. it seems though that if the drain hose on the bowl is puking gas, and the drain screw is tight, something is amiss? I was under the impression that the hose allows excess fuel to bleed off, regardless of the state of the bowl drain screw and that the screw is there to completely drain the carbs for storage. are you saying that isnt the case? 

If there is fuel coming out of the overflows with the drain screws closed then there is an issue with sticking floats or faulty float needle valves
PS: the overflow is there so that faulty floats won't pour fuel over a hot engine, not to bleed off any excess fuel potentially onto your rear tyre 

The float valve and seat are a set, that wear in together with usage.  You should never mix and match the needles and the seats, because a leak is likely to occur afterwards.

OEM Mikuni or Keyster brand float valves are the only ones that I'd trust.  I buy cheap Keyster rebuild kits for the KZ900, use the float valves, gaskets, and sometimes the pilot jets, and archive the rest.  This is cheaper than buying these parts separately.

www.siriusconinc.com/products/detail/562
 

ive been watching this. 
I think ive added to the issue by swapping out the float valve with one from my spare parts kz650 but its older and they are different. Im going to pop the carbs off again, swap it back and check the floats with a caliper. I also noticed on carb 3 the gasket was rubbing the float a bit, so ill shave that down. 

thanks for the tips and clarifications. Its tough when you dont know what you dont know. Ive rebuilt several sets of carbs, and ive never set the floats or synced them, I guess ive been lucky. These I had gone through by the guy on here or used to be, from texas. I dont want to mess with his setup too much 

xstreamcanadian wrote:

It ran this way perfectly up until now, so I doubt the hoses are bad.
 

I mean this in the nicest way possible: things work until they don't.

The hoses may be connected properly - which makes sense given how well it ran - but it's possible there was a failure in one or more of the hoses or other parts. When troubleshooting, it's a good practice to look at everything involved: if you skip certain parts because they're new or they worked yesterday, etc. you might be missing an important piece of data.

I was going to suggest that you switch to a gravity-type petcock for troubleshooting but it sounds like you already have one. The other suggestion would be to go to Partzilla, CMSNL, etc. and get a set of four new OEM float springs and other parts related to float operation. That way you'll have the correct spring rate and overall you'll have a better chance that the floats will behave correctly.

If there is fuel coming out of the float bowl overflow, the float in that carburetor is not moving correctly and is not shutting off the flow of fuel. It's possible the float is stuck, or it may have developed a hole and now has fuel in it (so it doesn't float any more).
 

completely agree. re the hoses, they are hoses, i mean, not a lot to "go wrong" there. I checked them all to ensure they are clear, hence the blowing on the drain hoses. I only meant that their configuration must be correct/ok, as it has not changed. Im ordering a new set of float needles. 

Nessism I used the wrong term. again. my apologies. I was meaning the float needles. they were all replaced brand new less than 100km ago. And again it ran very well. these are the correct kits for  my carbs www.siriusconinc.com/products/detail/921 just fyi. The one float needle seems to be kind of crappy spring wise, which is sad as again, its "new" but what are you going to do. Ill replace them all again, and see what happens. aka parts shotgun here we come 

these floats are solid type, not hollow plastic, so not sure they could get a hole in them. Ill double check thats a good idea. clearly the #2 float as you say is having issues 

this video is also pretty great I think. 
 

xstreamcanadian wrote:

Nessism I used the wrong term. again. my apologies. I was meaning the float needles. they were all replaced brand new less than 100km ago. And again it ran very well. these are the correct kits for  my carbs www.siriusconinc.com/products/detail/921 just fyi. The one float needle seems to be kind of crappy spring wise, which is sad as again, its "new" but what are you going to do. Ill replace them all again, and see what happens. aka parts shotgun here we come 

I do not like K&L carb kit parts, particularly the float valve, because the needle springs are too weak.  They won't hold up the weight of the float.  The floats tend to get a little heavy as they age, too, thus the fuel level can increase in the bowl, and for this reason it's important to perform the "clear tube" test as detailed in the factory service manual.  Checking float height is NOT good enough on it's own, you must check fuel level.

And just to be clear: a Float Valve = Float Seat + Float Needle

copy that. these needles seem a bit ghetto to me. ordering a set from the dealer