Carbs Leaking

When I bought my KZ1000 I put some fresh fuel in the tank to see if I could get it running. I noticed that there was gas leaking out of the carbs. Overnite it would leave a pretty good puddle on the floor. Is this because the carbs did not have the vent hoses on them or could it be something else? Please help.

Im no expert. But To me that tells me your floats are sticking and letting the bowls fill up to the point were its overflowing.

you might also check your petcock to make sure it is shutting off the fuel if it is not it will overflow your bowls and cause gas to leak good luck

Hi, you have 1, maybe 2 problems.

1) Your float needle and seat (valve assembly) is faulty - replacement is the best option I can recommend. I have not had good luck cleaning them after years of sitting or wear.

2) Your floats have lost some of their bouyancy and are not correctly adjusted. Sounds strange, but this has just happened to me and I would never believed it possible before now. Getting your floats set-up correctly using a fuel level gauge is the only way.

Your petcock has absolutely nothing to do with your over-flow problem. Sure it would stop new fuel transfer from the tank, but those bowls aren't going to leak in the first place if those floats are set correctly and those seats are in good shape - Period. Several of my Kawasaki triples don't even have a cut-off. They are vacuum operated. Floats and set properly working - no leaks.


Best Regards,
Gordon

Thanks Guys,
I will look into the float needle seals, and also look into adjusting the fuel level for the floats. I am sure they might need replacement parts as the bike had been sitting outdoors for about a year.

A dissenting opinion here:

Yes the Petcock left open will allow the gas to reach the needle valves in the carb and they often can and will stop all or part of the gas from getting through. But remember... that the number one reason that the needle valves are there is for regulating the height/level of the gas in the carb bowel so that the air/gas ratio, as metered-out by the jets, has as chance of being fairly constant... that's all. :dry:

IMHO, whether the Petcock is vacuum or mechanically operated it’s still the main gas shutoff valve never the less. True, new/good needle valves and seats can postpone the enevitiable gas seepage... but that's just a side effect. :dry:

Again, IMHO, a point is being lost here. Why are the needle valves so leaky? Are you sure you have an inline gas filter? If so, try a new one because the existing one may no longer being doing its job right... stuff may be getting through and lodged in the valve seats (don't ask how I know). :blush:

You may simply need to do a quick valve clean-out. If correct, this is a lot cheaper than new valve seat kits.

Best of success.

I would do the same but float neeedles are't too pricey.
henry

Because the fit between float needle and seat is so critical for sealing off the fuel flow, the float needle and seat are usually replaced as a matched pair. And this is of course why they should not be mixed and matched during re-assembly of carbs after disassembly for cleaning, jetting, etc.

Before removing the carbs from the bike, I would suggest doing two preliminary things:

(1) Remove the float bowl drain screws and allow fresh fuel from the tank to run through, as this might help flush out any crud at the needle/seat interface;

(2) Add some Seafoam to the tank and ride the bike enough to run through a couple of tankfuls, as this might help clean away any crud at the needle/seat interface.

Then if the problem persists with fuel continuing to drizzle from the floatbowls, would determine exactly which one or more of the four floatbowls is overflowing, as this will help determine which float/needle interface needs cleaning or parts replaced. One method is to place separate small containers to catch the overflow from the separate drain tubes, leave the petcock open (or on prime), leave overnight and inspect in the morning.
Another (less precise) method is the same idea, but use a clothespin or other clamp or plug at end of each drain tube to prevent its draining overnight. When opened in the morning, any accumulated fuel will flow from the tube.

Where must resort to pulling the carbs and removing the bowls, if the float needle tip isn't obviously worn, I would just clean the seat and re-use the same float needle with the same seat. It is easy to then bench-test the carb for any floatbowl overflow. And while at it, would also verify the correct service fuel levels by using the clear plastic tube method, which is also easy to do with carbs on the bench.

Good Luck!

As known, a properly functioning vacuum style petcock in the normal run position is indeed "off" until opened by vacuum produced by a running engine. Whereas a properly functioning manual petcock is either "on" or "off" regardless of whether the engine is running or not running.

And yes it's true the float needle/seat interface isn't for the purpose of serving as a fuel shut-off. But it's also true that a properly functioning float needle/seat interface (such as when the bike was new) manages by itself alone to prevent any fuel passage even though the petcock is allowing fuel from the tank.

Meanwhile, it's still the better practice to turn off the petcock when the engine isn't running. And rumor has it Ma-Kaw adopted the vacuum style petcock to assure fuel flow being discontinued from the tank when the engine wasn't running.

For example, unbeknownst to the owner, a speck of grit may begin interferring with and preventing full closure of the interface shortly before the bike is parked and engine shut off. Let's say the owner walks away leaving the petcock ON. What happens then? Supposedly, the excess fuel running into the floatbowl through the failed float needle/seat interface runs out the floatbowl overflows without further drama. But what if the overflow is clogged or the carbs (such as 29 smoothbores) do not have floatbowl overflows? Where does the excess fuel go? Unfortunately, it goes up into the carb throat and flows from there both ways. One way is toward the engine and on into the combustion chamber, then down around the pistons and into the crankcase. The other way is back toward the air filter. Not so much a problem with pods because the excess fuel just runs through the pod filters to the outside world. But mucho problem where the excess fuel flows into an airbox and drains from the airbox down through the crankcase breather vent tube directly into the crankcase. That's the reason many smoothbore users disconnect the crankcase vent hose from the airbox and route it to the outside underneath the bike. And must still keep close watch on the float needle/seat interface to guard against excess fuel being allowed to run toward the engine into the combustion chambers and down around the pistons into the crankcase. So it's the better practice to turn a manual petcock OFF when the engine isn't running.

The bad news -- with a clogged or non-existent overflow circuit to discharge excess fuel inside the floatbowl, the excess fuel may be allowed into the crankcase during on-the-road operation of the motorcycle. And that alone is a really good reason to assure the float needle/seat interface continues perfectly sealing as it's supposed to, regardless of whether the petcock is always turned off while the engine isn't running. And especially where the airbox remains connected to the crankcase vent.

Fuel draining out onto the floor is bad enough.
But it's far worse when excess fuel gets into crankcase.

You know what to do.

Good Luck!

Ok, I have had this problem on both my 650 B and my 1000 st.

Please dont waste your time or money on this problem pulling the carbs unless it is not fixed by the following suggestion.

I solved this issue by rapping on the carbs with a rubber mallet and by throwing the bike up on the c stand a few times with a little extra umph. Wht ever junk is in there will come loose if it is under your needles.

Do not hit the carbs to hard to damage them, but give them a good jostle.

Also, threw some new spark plugs in the bike and have never experienced this problem again.

Cost me 10 mins of time and $12.00 for a pair of plugs.

You need to take your bike for a nice long run and then check to see if this has soved your problem.

I would do this first before over complicating the issue. If this does not fix your problem, then pull the carbs and poke around in there.

Anyone else have this fix there problem, I have heard of a few guys doing the same thing and it worked for them.

It usually happens when the bike has been sitting for a while.