weak needle valves causing leak?

[claygs750e]

I went ahead and ordered the set from Z1 so I'll report back after they are installed and hopefully this resolves my issue. Thanks again everyone.

[JTGS850GL]

And I agree on the mini shock absorption too. The OP moved the needle to another carb..presumably with the same float hts set but the leak followed.

The needle with the good spring didnt leak and the bad one did. Why didnt the one with the good one leak even when moved around? WHAT one SINGLE FACTOR followed from carb to carb and made it leak..the spring. Why the spring? Because it wasnt applying upward pressure like the ones with good springs are doing.
Say whatever you want, but that spring DOES INDEED assert pressure on the needle to keep it seated upward.

Dont move a single thing in any of the other carbs that werent leaking and break one of the springs from holding against the needle and youll get the same thing again. The only factor that has changed in my scenario is the PRESSURE the spring was asserting before it was broke...but you dont want to hear the truth.

Maybe the float valve is bad and the week spring has no bearing on it leaking.

OR

A very weak or broken spring can cause the pin height to be so far out of position that the tab hits the edge of the valve seat before the valve is completely closed. Seen it.

The spring loaded pin is a shock absorber. No other reason then that. Don't confuse the design purpose of a mechanism with the results of a broken one.

[bwringer]

I once installed new needles from a kit. After a VERY frustrating few months, I finally discovered that the shoddy aftermarket needles had much weaker springs than the OEM needles, and two were actually sticking. Upon closer examination, the seats were also visibly different -- different size holes and poorly finished seating areas.

It was about then that I swore a dire oath to NEVER waste my money on carb kits again, and to prevent anyone else from doing so whenever possible. The only usable parts out of $100 in carb kits turned out to be the bowl gaskets.

The springs in OEM needles are strong enough to hold the floats up without compressing at all when the carbs are upside-down. Make sure yours fit this description.

Also, the shoddy aftermarket needles are much softer. The stock needles will last darn near forever, but the aftermarket needles will develop grooves after a very short time. Someone posted pics a while back showing the difference.

[chuck hahn]

Hey JTG850..take a known good carb and do absolutely nothing to it (other than break that spring) and then come and tell me the spring has absolutely nothing to do with it. That biitch will leak like a payday hooker at shift change!!!!!!

[JTGS850GL]

Hey JTG850..take a known good carb and do absolutely nothing to it (other than break that spring) and then come and tell me the spring has absolutely nothing to do with it. That biitch will leak like a payday hooker at shift change!!!!!!

Hey chuck!!! Did you even read my post above? Here, let me make it easier for you.

A very weak or broken spring can cause the pin height to be so far out of position that the tab hits the edge of the valve seat before the valve is completely closed.

As stated, I agree that a broken spring can cause the float to leak, but not for the reasons you state.

If the pin sticks then the float height will change depending on when and where it sticks. This would alter the set point of the float and thus effect the fuel height.

If the pin spring is broken, then the total length of the valve will be reduced to the point of the tab not being able to push it up high enough to shut the flow off.

If the spring is weak, then it will get weaker in a short time and will cause the height to change as well.

These are reasons the spring can effect fuel level. Like I said... Don't confuse the original design purpose of a component with the results of a defective component.

The spring loaded pin is designed to absorb shock. PERIOD. The buoyancy of the float is what shuts the valve off. Not some distorted concept of a PoGo stick effect forcing the valve closed.

[claygs750e]

So are you saying the set I bought from Z1 might not fix the problem or they just won't hold up as well over time when compared to OEM? If somehow it turns out not to be the valve needles and the floats are to spec for height what would be my next step for the gas leak?

[chuck hahn]

Again I disagree because I have had it happen form that exact reason...and that reason alone. Spring was broke and the needle fell about 2MM lower than the rest when I lifted the floats and looked at them all. Put in a needle with a good spring and that fixed it. Changed absolutely nothing else and the only common denominator was the spring.


Do it to your carbs once!!!

[JTGS850GL]

Again I disagree because I have had it happen form that exact reason...and that reason alone. Spring was broke and the needle fell about 2MM lower than the rest when I lifted the floats and looked at them all. Put in a needle with a good spring and that fixed it. Changed absolutely nothing else and the only common denominator was the spring.


Do it to your carbs once!!!

Pretty much what I said... If it's broke then it wont work as designed. A broken pin spring will leave the total length of the float valve too short to work. I don't understand why you keep arguing about it. All I've ever said is that the purpose of the spring loaded pin was to act as a shock absorber and keep the float from hammering the seat. The only area I didn't agree with you on is that the spring forces the seat closed by design. That's not the reason for the design including a spring loaded pin.

As an experiment, take a working float valve and put a small dab of glue at the base of the pin to lock it up. The float valve will still work even though the spring is now effectively disabled.

[tkent02]

Its easier to argue with asparagus than hammers.

It listens to reason a little bit.

[bwringer]

So are you saying the set I bought from Z1 might not fix the problem or they just won't hold up as well over time when compared to OEM? If somehow it turns out not to be the valve needles and the floats are to spec for height what would be my next step for the gas leak?

One test is easy to make -- take the carbs off, remove the bowls, flip the carbs upside-down, and see if the springs in the needles are strong enough to hold the floats up without compressing at all (that's how OEM needles work). The springs compress easily if you poke a float with a finger, of course, but they should not compress at all under just the weight of a float. If they don't pass this test, you'll never be able to set a correct float height. Throw them in the garbage.

The other test is not as easy to make: after a few months or many years of use, the needles should show no visible wear. Many aftermarket needles are much softer than the OEM needles, and will quickly develop visible lines in the metal and wear rapidly.


Much as I love Z1, they sell K&L carb kits and parts, which in my experience and that of many others, exhibit the problems outlined above. Unless K&L has suddenly improved its quality recently, be cautious.

[claygs750e]

We'll I'm not sure what's going on now. I received the new needles and replaced all four, then adjusted the float height to right at 22mm. The floats themselves are in good condition. Some of the needles no matter what I did depressed slightly. Reattached the carbs and still leaking out of carbs 3 and 4 out of the vent tube, spraying out of the air jet hole.Is the problem still the fact the needle springs are depressing? I pushed the tab pretty high, but it started getting far out of spec. So What else could be causing this problem?

[JTGS850GL]

Some of the needles no matter what I did depressed slightly.

Please clarify... Are the new needles OEM or aftermarket? Explain what you mean that they depressed slightly?

Even if the needles are good, you didn't replace the seats. No matter how good the needles are, if the seats are bad they will still leak.

With that said, can you post some pics of the carbs? Please include pics of the float height and the needles on all the carbs. If the new needles worked on carbs 1 & 2 then they should have worked on 3 & 4 if the seats are in good working order.

[JEEPRUSTY]

Golly gee gas could even be leaking around the seat to body joint via the o ring

replaced all your o rings?

[JTGS850GL]

Sorry, assumed that the O-rings were already replaced.

[claygs750e]

Yea, I did a complete o-ring kit, dyno stage 3 kit for pods and aftermarket pipes and now new needles.

So, after my last post I removed the carbs again and removed the floats. I sprayed water in the seats and the water drain out. I then inserted the needles only and sprayed water in the seats and the needles held the water in with their own weight. So wouldn't that tell me the seal between the seat and needle is good since it's not letting water through? So....even though all the floats were at 22mm I thought maybe they are too low and the floats aren't pushing the needle up far enough. I adjusted the tab where the float now is at 25mm. I started the bike and after an initial leak (had it on prime too long maybe to fill the bowls) then no leak at all and the bike is running good. So was that all it was? Floats were too low even though they were spec?