Carb leak flow related to vacuum line?

I bought a bike last weekend and have been working on it some (see my other noob related threads). I was told that there was a small carb leak. I just added some Sea Foam to hopefully take care of the issue. So here's my question. When I was poking around under the tank I saw the vacuum line was disconnected at the fuel tap. I reconnected it, and now the carb leak seems to be at a higher flow. Is this possible? Am I just noticing it more, or should I re-disconnect the vacuum line until the carb leak is fixed?

gte105u wrote:

I bought a bike last weekend and have been working on it some (see my other noob related threads). I was told that there was a small carb leak. I just added some Sea Foam to hopefully take care of the issue. So here's my question. When I was poking around under the tank I saw the vacuum line was disconnected at the fuel tap. I reconnected it, and now the carb leak seems to be at a higher flow. Is this possible? Am I just noticing it more, or should I re-disconnect the vacuum line until the carb leak is fixed?

Vac line should remain connected to petcock. If not connected, the vac line should be plugged, or capped at the carb nipple.

Is the carb leakage issue while the engine is running?

When engine isn't running, carb leakage likely not influenced by whether or not vac line is connected to petcock.

Initial guess would be leaking float valve(s), and perhaps petcock not performing up to snuff.

Good Fortune!

As far as I can tell it is only while the engine is not running. I figured it would not influence much, and I was just noticing it more. The other factor is that when I bought the bike the overflow lines were missing. I installed them back, so I am probably noticing it more since the flow is concentrated. I hope the Sea Foam works...

May want to assure that carb end of vac tube is connected to a carb vac nipple, and NOT to a carb float bowl vent nipple.

Here's an example (see below).

In this example, the vac to petcock is on #2 carb.
Sometimes the vac to petcock is on #3 carb.
Other carbs don't have a separate dedicated vac to petcock nipple, and just use one of the vac sync nipples to supply vacuum to a vacuum petcock.

Unless used to supply vacuum to a vacuum petcock, or used incident to a "clean air" hose system, a vac nipple should be plugged during normal operation.
In other words, an unused vac nipple should be plugged during normal operation.

An open unplugged vac nipple will create a huge air leak.

Good Fortune!

[Click on image to enhance view.]

Thanks for the heads up. Is the vacuum line coming from the between carbs 1 and 2 or 3 and 4? There is only one line under the tank besides the fuel line, and it is coming from near carb 4. Is the vacuum line towards the front or back of the vent?

gte105u wrote:

Thanks for the heads up. Is the vacuum line coming from the between carbs 1 and 2 or 3 and 4? There is only one line under the tank besides the fuel line, and it is coming from near carb 4. Is the vacuum line towards the front or back of the vent?

The earlier posted pic is a view when looking at the carbs from the rear where the air enters.

Those carbs have vac nipple between 1st and 2nd carbs where the tube attaches that runs from there to the petcock.

As noted, some carbs have such vac nipple between 3rd and 4th carbs.

While other carbs have no such dedicated vac nipple at all.

When carbs do have the vac nipple between 1st and 2nd or between 3rd and 4th, it's easy to confuse such vac nipple with either of the two VENT nipples. As shown, one vent nipple is between carbs # and #2. And the other vent nipple is between carbs #3 and #4.

The two vent nipples run though their attached tubes to open air, often underneath the seat or underneath the bike.

Here's a pic showing one of the two vent hoses (see below).

Good Fortune!

[Click on image to enhance view.]

[Click on image to enhance view.]

Hey guys, thanks for all the help. I am sorry I am so full of noob questions... this is my first bike I have bought which needed a lot of "love" from the beginning. All I could afford... but I am actually enjoying getting to know her as well.

Anyway, after digging through the Kawasaki parts diagrams, I think I know what I am looking for. It looks like there are two vent nipples feeding from one location between carbs 3 and for. Does it matter where they run to? The vents are behind (towards the back of the bike) the vac line, also between carbs 3 and 4. Please take a look at the pics below and advise if I am missing anything here. Thanks again

Sound like the fuel level in your carbs are to high, needle not seating or possible leak in float. Before pulling the carbs off you could try to "Flush the needle" by draining the carb that is having the issue, and with the drain screw out turn the petcock to Prime and let some fuel run through with the float hanging down. This will wash it a bit if there is a piece of crud in there it might wash it through. You do run a inline fuel filter, right? If that doesn't do it bite the bullet and get a set of kits and do the job right.

I imagine it is the float needle as well. I just bought the bike so I cannot say for sure about the fuel filter... but from what I am seeing of other things from the previous owner probably not likely. I just added a decent bit of Sea Foam with this fill-up. I am going to give it a few days of working in to try and loosen up any gunk in the carbs then flush.

Let us know if the bottle of "Foam" works, better see if there is a filter or that stuff may add some more junk into your carbs, all of the old residue in the tank.

I just looked. The line coming across that was not connected is the vac line. There also is an inline filter. I don't know if it is any good or not (or if there really is a better or worse kind). I looks just like this one, though I did not have the lighting to really look well and see the brand.