#1 cylinder is eating spark plugs

bountyhunter wrote:

I doubt it, I think you are getting a poor seal at the #1 needle/brass seat interface. You can greatly improve the seal at the needle by spinning the needle at polishing the tapered end with #600 paper until it is mirror smooth. Spin the brass seat and polish with a Q tip and chrome polish inside where the needle goes. I do that as regular maintenance with a hand drill. The leaking gas floods that cylinder and makes it impossible to fire that plug.

BTW: if your petcock is cutting off well, the gas in the lines should not be able to "drain down" since there would be a vacuum lock holding the fuel in the gas lines. That assumes there are no air leaks in the fuel lines above the carbs, but they shouldn't continue to flow down.

DO THIS.

TeK9iNe wrote:

bountyhunter wrote:

I doubt it, I think you are getting a poor seal at the #1 needle/brass seat interface. You can greatly improve the seal at the needle by spinning the needle at polishing the tapered end with #600 paper until it is mirror smooth. Spin the brass seat and polish with a Q tip and chrome polish inside where the needle goes. I do that as regular maintenance with a hand drill. The leaking gas floods that cylinder and makes it impossible to fire that plug.

BTW: if your petcock is cutting off well, the gas in the lines should not be able to "drain down" since there would be a vacuum lock holding the fuel in the gas lines. That assumes there are no air leaks in the fuel lines above the carbs, but they shouldn't continue to flow down.

DO THIS.

Could this really be the problem even though these parts are new? All parts made in Japan, bought from z1 enterprises.

Last night, before considering what some of you said, I put a wood block under the side stand to make the bike more centered. This morning, almost no gas had leaked out, which might mean, like someone said, that the gas leak just spread out to all four cylinders, but not sure. I ordered new float pins so that i will be able to say that all internal parts are new.

Im really considering just ditching these carbs and get a new set keihin racing carbs. Im really frustrated.

cobura wrote:

Could this really be the problem even though these parts are new? ...

...I ordered new float pins so that i will be able to say that all internal parts are new.

Im really considering just ditching these carbs and get a new set keihin racing carbs. Im really frustrated.

I don't get this?

You need new/clean float pins to stop the gas.
Bench check the carbs. Stand them up off the bike and hook the gas up to them. Then leave them overnight and check the gas flowing out of them the next day...

A new set of carbs would have a new set of float pins...

GL.

Once again, unless your pingle is bad, there has to be some vacuum still sucking the gas from the tank to the carbs. When gas is off there should be NO gas WHATSOEVER unless of course the petcock is faulty or the vacuum line is plugged up somewhere.
Too, I had to replace the needles in my zr and that was EXPENSIVE! In retrospect I should have just ditched them and bought some new Keihins or Mikuni Flatsides. Because the needle coating was corroded it cost me over 150 just for the float needles and I guess that was stupid of me to do because the actual insides were probably corroded too. The needle valves should stop the gas flow so assuming the floats are set correctly they may still leak gas if the needle valves are worn out. I never was able to fix the problem myself and when I took the bike to a mechanic he couldn't diagnose where the problem was coming from either. I would say if your carbs are working fine stay with them and just get those floats set properly, make sure the needles are in good shape that cut the gas off in the carbs and by all means check out the vacuum lines. Make sure they are not plugged up or crimped by the tank somehow. And most of all be PATIENT. lol I know it's hard but this is probably just a small easy fix. But man! If those float pins are rusted up????? HMMMMM I have never ever seen something like that before. I have seen the internals of several carbs and not once have I seen that. Well, good luck. If we had more info we probably could tell you but there are so many variables that could be causing the problem. You have an old bike so there are always gremlins but once you get them worked out it may be just fine. Me, I am about finished with mine. Old bikes often cost more than new bikes do if you put any real money in to them. I don't even want to say what I have in to mine. I still am not finished yet. Let's just say that I could have bought a brand new ZX14. If I had it to do over I think I would still have kept to my bike and left the new rocketship alone. Although.... wouldn't be bad to have both.

Id pull the gas line off the carbs and place it over a dry container over night. If it leaks your petcocks to blame
Or try riding with it in the off position to see if it runs out gas.

Has an in-line fuel filter always been used since the new float valves were installed?

If not, the new float valve may have been instantly contaminated.

Might also want to double-check that the float wasn't accidentally installed upside down.

If the float pin is so ragged that movement of the float isn't virtually friction-free, it's conceivable that there might be enough "drag" on the movement whereby the float's natural buoyancy is unable to press hard enough against the needle to sufficiently push the needle point into the seat orifice. Or perhaps the float pin channel is bent or damaged where the pin passes through so as to cause some binding.

As known, the rising float is supposed to push its tang against the float needle to press the needle into the seat orifice which stops the flow at prescribed level in the bowl. When this doesn't happen, for whatever reason, excess fuel escapes through the overflow circuit and out through the nipple from bottom of float bowl.

Just thoughts.

Good Fortune!

I hear all of you, thanks for the advice. To answer some questions:

yes an inline fuel filter has always been new. Tank is also clean and re-coated, so no contamination.

If i ride with the cock in OFF position, it DOES run out of gas.

The float pins were not rusty, just a little bit rough. It looks like someone had used pliers to remove them before or something. But I used a air drill and sandpaper to smooth them down really nice. Im not convinced however that they are OK, which is why i ordered new ones.

Since three days ago, i removed the wooden blocks from under the sidestand and set it back to how it was before. I've checked it every day and there is absolutely no gas leaking at all. Not one drop. It seems now that it only leaks gas after it has been ridden. Once that amount of gas has leaked out, it stops. This could be what i said before, maybe its just the gas still left in the line. One thing i was thinking, maybe the hose that i am using is not a tight enough fit. Tomorrow i will go to buy some wire and place a better crimps on the line.

cobura wrote:

...If i ride with the cock in OFF position, it DOES run out of gas...only leaks gas after it has been ridden. Once that amount of gas has leaked out, it stops....

Perhaps a flanged corner of the float bowl has gotten bent from over-tightening (see image below), which can prevent complete sealing of the bowl against the carb body when the four screws are tightened, regardless of having a new or good used gasket.

This condition may sometimes be resolved by using a double gasket OR by carefully realigning the corner tab on the float bowl by bending it back into correct position before re-attaching the float bowl.

If using a manual petcock, may turn it OFF a mile before ending the ride, and then running the engine at idle long enough to empty the float bowl before parking the bike. With an empty float bowl and no fuel supply, gasoline won't reach the overflow circuit.

Good Fortune!

[Click on image to enhance view.]