#1 carb still leaking, please help!

[PJSALERNO]

78XS11 E

Had a #1carb leak even when engine off, so decided to tear em all down and rebuild them.

I broke down all four carbs, cleaned them and replaced all jets, gasgets and needles. Was very careful in setting the float heigths to exactly 1".

Also rebuilt both petcocks.

No leaks on prime, the bike fired right up, runs excellent, but #1 carb leaks 1 drop per second. Shut engine off, leak stops.

1 other piece of ifo, I decidend NOT to replace the valve seats for the floats, because the new ones seemed like they didnt have enough spring. The old ones had no visible wear. When blowing through the gas line and lifting up the floats, i could not blow any more air, so it looks like the valve worked. I also swapped #1 and #3 valve seat and the leak stayed with #1.

Any advice?????? please! Thanks...Phil

[sixtysix]

Where does it leak from? Does it leak back up through the air inlet? this is where a typical float or needle seat problem would be. If so I assume you have the carbs on with no air cleaner so you can see which one it is? More info please.....

[PJSALERNO]

Nice, Gary, good point. No, I have the whole lot back together and it is difficult to locate where the leak is originating.. I'll take off the air box and put the tank on backwards wear the seat goes and get a good view of the leak, then get back at cha. Cheers..Phil

[RiskyBusiness]

I replied to your other post about the float height before I saw this one. Another question now: What is more springgy? If I recall, the float valve seat does not have a spring at all. It is moved directly by the float.

Where do you see the fuel that is leaking out? If the bike is running and you are seeing fuel drip off the bottom of the carb, I would bet money on it leaking from either the gasket or the bottom screw. Is the side fo the carb wet? One drop a sec is a pretty good flow... you should be able to trace a trail.

Post a follow up and let us know how that leak hunt is going.

[PJSALERNO]

I'm gonna trace the leak tonite, after work and will post results tomorrow.

I guess I used the wrong term. The valves themselves has a little "piston" that has a spring to it and pushes up on the float tang. The new valves had less tension, therefore when setting the float height while the carbs were upside down, the tangs would have to be bent alot to get the correct height. i didnt use these new valves, i used the old ones. But switched #1 and #3 and the leak stayed with #1. Maybe the float is getting hung on the side of the bowl which of course I cant witness with the bowl off.

More later, thanks...phil

[James L]

leaky float maybe?

Phil,
If a float had a hole in it, it may not *float* at all. You might verify the float itself is not taking gas in.
Old brass floats seem more susceptible to leaks than the newer plastic ones.
Folks have soldered leaky brass floats successfully, but I was too chicken to try it with mine.
One time I destroyed a brass lawnmower float trying to solder it, that stuff is really thin! I used JB weld on my XS11's floats, it's holding up just fine.
Good luck finding your leak!

[Snow]

You say it doesn't leak when on prime, right? Even if you let it sit for 10-15 minutes?
They are 78 carbs also (I am assuming), that have the pressure equalizing tubes that look very much like the gas inlet tubes - do you have those vent tubes hooked up to the airbox? Make sure the airbox connectors are not plugged off like they were on my bike.

Also, if the floats are getting hung up, try taking the plastic end up a screwdriver and giving the float bowls a couple love taps (be sure to not mar up the bowls) while they are on the bike and see if that helps at all. But again, be very careful if you do that as they get buggered up really easily.

[PJSALERNO]

Leak found and stopped! It was the t-connector on the gas inlet to #1/#2 carbs. It was bent on an upward 45 degree angle. Once I made it paralell to the ground in stopped leaking. Thanks for all the advice.

One more Q......Idle Mixture screw. While on the bench, I gently closed them, then backed out 1-1/4 turns. All the tech tips I have found on fine tuning are a little complicated to me. Any simple procedure on adjusting for optimum performance would be helpful. Cheers, Phil

[sixtysix]

Simplest way is to set them at 1 1/2 turns and never even think about them again!! But if you want to mess with it, I just go by seat of the pants...if it is way too lean the idle will hang, if it just a little lean the idle will be fine but if you put the bike in second gear and slowly run the RPMs up to about 4K (where the idle circuit no longer controls fuel flow in the carb) it will buck or surge a little, the sooner it happens the leaner it is. If it is a little rich, you just get lower milage, bike runs great, real rich and the idle will actually dip when the thottle is 'blipped' (very quick, short twist), plugs will be black, black smoke when revved. I actually own a color tune but never use it , the procedure above seems to work. if you go less than one turn or more than 4 than something is wrong, most likely wrong pilots.

If you don't notice any of the lean indicators above then you are probably OK at 1.25 turns.

[XJ1100CRAZY]

Thanks guys,now I know where to look for my leak. (somewhere around the third carb)....
great site !!