Carb Dripping While Idling

Carbs, sucking the fun out of xj ownership since the early 80's.... I have an 82 650 Seca, I brought it back from the dead last summer and it runs exceptionally well albeit for one issue. my 4th carb is dripping gas from the two screws (circled in the representational pic) I thought these screws only attached the carb to the rack, but i'm not sure I haven't removed them and they're both tight. I replaced the float bowl gasket assuming it as the issue but the drips continue. any advice wold be appreciated. I can provide more pics or video if it would help...

 

It drips because the float needle(s) isn't/aren't seating.

Homework time:
IN THE CHURCH OF CLEAN

 

Full blown Teacher mode!

 

So likely a float height issue? Weird because when I turn it to prime no drips... Seems to be only at idle...

 

Float height is not necessarily the cause.
Pop the oil cap off and have a sniff. What's it smell like?

Might be a petcock issue, but lets take things on step at a time.

 

Smells like warm oil... Level is right in the middle of the sight glass. Plug looks good (a tough lean with the pod filter but good otherwise.

 

Are all of your screws tight on the carbs? Hows the fuel line look?

 

Have seen float put in upside down .. Yes Upside down and the bike ran but kept leaking gas , so PO gave up on it so I got it cheap

 

He says the bike runs fine, so lets ease off on the Church junk. So while the bike is idling, with the petcock "on" it drips, but with the petcock set to "prime" (still while idling), it does not drip?

 

his answers are still in the C.O.C
needle valve needs cleaning/replacment , or the seal for the valve body is failing.
then there is the possibility his wet set height is to high.

eliminating what could be the cause is how he will find the problem

could be a petcock issue but what is forcing the fuel past the needle valve to cause a leak?

what other parts did you replace in the carbs?

 

check needle and seat...if it rubber tipped does it have a circular pattern? first hint it might not seal correctly. Doh XJ5550H beat me to the punch... Check all he listed !!!!

 

Needle actually looked good to me (soft little pyramid), I think it may be a wet float height issue. A buddy gave me the bike and the carbs were a disaster, I went through them 3 times based on the excellent C.O.C guide before giving up when I kept experiencing a cool cylinder (always cylinder #4) running extremely rich, gave it to a mechanic who indicated that the diaphragm spring wasn't properly seated and was "bunching" gave it back to me and now it'll out pull a brand new Aston Martin (albeit dripping a bit of gas....) Even at it's most gunked up it never leaked and i ordered and gave him new float needles though i see the stock one was still installed (never got back my brand new replacements). I'll remove the rack again this weekend. I don't think its a fuel line/petcock issue as this is the carb farthest from... my last bike was fuel injected and I must say 4 carbs on a 34 year old bike are driving me nuts.

 

check fuel height before pulling carbs
link
Setting the fuel levels

 

If there is no oil in the gas then this is not necessarily Church issue, and definitely not a float needle/ float/ float nedle seat issue.

Petcock.

Unhook the fuel line from the carbs.
Clamp the free end so fuel can't come out.
Set the petcock ON.
Is there a leak?
If so, where from?

Slightly related question:
Is the vacuum line from the petcock connected to the intake for the #4 carb by chance?

 

you didn't answer DrewUth's question. Does it leak at idle when set to Prime? If not, then it would not seem to be a float/needle issue. If it does leak at idle in any petcock position then it probably is a float/needle issue. If you want to eliminate the petcock, hook up an auxillary fuel tank and see if it still leaks.

 

bought an IV fuel bottle and ruled out fuel line, petcock etc. ordered a rebuild kit and will change out the needle etc see if that makes a difference...

 

Did you disconnect the petcock vacuum line when you ran from the IV bottle? When the diaphragm in the petcock starts to go it can leak fuel through the vac line.

 

Hang on, i have a 81 XJ 650. Is there a specific intake for the vacuum line? I believe mine is on 3 or 4. (going from left to right, where leftest is 1)

 

Sounds like a bad oring in the gas linkage.

 

no any port can be used
kmoe may have been asking because carb 4 was leaking and if petcock was leaking into vac hose and was connected to #4 port that would explain the drip

 

Exactly.

 

mc1oo1 got it, I held my breath and started to pull the rack apart and one of the o rings had almost completely disintegrated. I'll hunt down a replacement and fingers crossed will have a clean, dry carb by the weekend! Thanks to all for the input!