Leaky carb doing my head in.

Plug all the vacuum ports.  Leave the float bowl vents open.

As I understand it (happy to be corrected) the float valves are a purely mechanical device so the vac lines should have no effect on their operation (the vacum ports are connected to the intake tracts not the float bowls) the float bowls are vented to atmosphere (or they wouldn't fill) but the vent should be above the fuel level (or the tank would empty through them as fluid will try and find it's own level) - I believe the reference to the petcock vacum line was simply if the petcock was faulty it may supply fuel via the vacum port and flood the inlet tract. Two questions

• Where in the #2 carb is the fuel coming from ?
• How high above the carbs is the auxiliary fuel tank ? (the carbs will flood if the fuel pressure is high enough to overcome the float valve)

Wookie58 wrote:

As I understand it (happy to be corrected) the float valves are a purely mechanical device so the vac lines should have no effect on their operation (the vacum ports are connected to the intake tracts not the float bowls) the float bowls are vented to atmosphere (or they wouldn't fill) but the vent should be above the fuel level (or the tank would empty through them as fluid will try and find it's own level) - I believe the reference to the petcock vacum line was simply if the petcock was faulty it may supply fuel via the vacum port and flood the inlet tract. Two questions

• Where in the #2 carb is the fuel coming from ?
• How high above the carbs is the auxiliary fuel tank ? (the carbs will flood if the fuel pressure is high enough to overcome the float valve)

Fuel is coming up from the float bowl,through the main/needle jet and flowing out of the airbox port. I have the top (diaphram/spring/needle) off the carb to have a clear view.I dont believe having the top off is affecting anything as it still leaks with the top on. Plus,I also pulled the top off No.1 carb,to compare and that had no ill effect on No.1 carb.
 The remote fuel supply is maybe half a meter above the whole set up,so more pressure than standard tank height for sure but again,No.1,3 and 4 carbs have no problem.
 I was hoping the vacuum thing could be the answer but maybe that was hopeful thinking. I get the feeling that it's something very simple,that I have missed,as all the mechanics seem to be in order.

I'll try and get some photos/video posted.

That shouldn't matter with the clear tube test. Just got done with #1 carb. It was acting just like yours. Seems crap was getting past the screen on the seat and caused all kinds of SHT. Just for GP I'm going to polish the seat and needle. 
Steve

Nessism wrote:

Plug all the vacuum ports.  Leave the float bowl vents open.
 

What/Where are float bowl vents?

Bowl vents. David, depends on which version of 34's You have? They went about it differently on different types. You have Your basic 34's, black plastic TEE between 1 and 2/3 and 4 then they had one that vented (2) casting holes, thru intake as highlighted in blue. These are the air-cut style Kawasaki ones. Others shown are Suzuki GS and Yamaha XS, they also used the black plastic TEE. I'm still suspect of float tower to float or float pin bind.    

asphalt900 wrote:

Bowl vents. David, depends on which version of 34's You have? They went about it differently on different types. You have Your basic 34's, black plastic TEE between 1 and 2/3 and 4 then they had one that vented (2) casting holes, thru intake as highlighted in blue. These are the air-cut style Kawasaki ones. Others shown are Suzuki GS and Yamaha XS, they also used the black plastic TEE. I'm still suspect of float tower to float or float pin bind.  

 

 

That explains why mine were flooding. Changed the O rings but didn't clean out #1 Like I did the rest. The old ones were crusty and falling apart. Seems to me having the vents in the vacuum path would cause negative pressure in the bowls or how does that work? Looked to me the vents were in a casting on the sides but judging on how it was flooding I guess I was wrong. It was coming out of the two holes you have circled in blue. Got it now. 
Steve
  

SWest wrote:

That explains why mine were flooding. Changed the O rings but didn't clean out #1 Like I did the rest. The old ones were crusty and falling apart. Seems to me having the vents in the vacuum path would cause negative pressure in the bowls or how does that work? Looked to me the vents were in a casting on the sides but judging on how it was flooding I guess I was wrong. It was coming out of the two holes you have circled in blue. Got it now. 

 

It certainly does seem strange (I was always under the impression the bowls needed "atmospheric pressure" through the vents) still "every day is a school day" - the stock airbox on my "K" was so restrictive the negative pressure must have been significant when the motor was singing !!!

Wookie I agree and have thought the same regarding bowl vents in the carb intake bell.  I think no matter what the pressure difference is present there will be a difference between fuel in the bowl and air entering the carb intake bell. Keep in mind it is just a vent, not a jet and it works in both directions. Air in as the fuel level drops and air out as fuel level increases. 
At least that is how I see it.

Got to say I was intrigued by this (Wookie's are easily distracted !!) so I found the below diagrams which may make it a little clearer (doesn't help solve your problem though Davido  )

For how long this has been happening, it's really starting to bother me, and it's not even my carbs!

For the sake of sanity:
- Try swapping SINGLE components from a known working carb, to the leaking carb. As in JUST the float, just the float valve, just the float seat. that kind of stuff. heck, even try swapping the bowls. but, one at a time. if you swap all the bottom end components at once, you wont know the culprit.

- You mentioned that there's no witness marks on the bowls or floats from contact. being plastic versus aluminum, there might not be. Looking at the floats, carb upside down, from above, is the float arm "straight"? are the float faces parallel to each other? 

- looking closely at the individual float valves, does the spring pressure seem equal between different valves? if you slowly press two valve spring pins against each other, are they equally pressed in?

- outside the carb, in all orientations does the spring pin on the float valve in question move "normally"? what about while submerged? perhaps there's debris that's made its way past the pin and only wreaking havoc with the pin vertical and liquid present to "slosh" it around inside the valve?

- i doubt it's the overflow between carbs because that's quite a bit higher. scowling while thinking noises

- if you "plug" number 2's valve, do any of the others start to overflow without 2 acting as a pressure relief?

Boys and Girls, we have a winner. Could Nessism (and Asphalt 900) please stand up. A round of applause everyone. Thank you.
 Yes,looks like it was the bowl vents.But not a blockage in the traditional way. Just me doing something stupid. (I new it was going to come down to that). I built a nice rack to hold the carbs and keep them level while doing the fuel level adjustment. Also with a swivel so I could flip everything over to get to the bowls. Problem is,to hold the carbs in, I had a plank across the airbox ports on one side and a plank across the engine ports with a couple of clamps to hold everything together. I must have been blocking the bowl vents on No.2!!
 As soon as I took the carbs out of the rack to check the vents I turned the fuel on and ....No leak. Everything in order. Fantastic.
Tomorrow,I have to adapt the rack so it will hold the carbs without blocking anything, then I can finally get the fuel levels checked and adjusted.(fingers crossed)
I want to thank everybody for helping out. It was a great response and I appreciate it.
(and KeylAmi, thanks for feeling my pain.)