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Author Topic: Carb overflow lines dripping gas! Help! SISF?  (Read 6340 times)

Offline gregman_1

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Carb overflow lines dripping gas! Help! SISF?
« on: January 01, 2015, 01:25:59 PM »
About 35k miles ago, Steve went through my carbs and did the jet kit and overflow tubes.  Absolutely the best money I've spent on my bike.

Here's what I've got going on, I am so frustrated that I need someone else's brain on it as mine can't think straight about it. A couple thousand miles ago (about 50k or so), the bike started dripping gas from the bowl overflow line while the bike was running (or with the petcock on prime). I figured it was a dirty or leaking needle seat, pulled the carbs (ugh), and sure enough, a sliver of rubber in the #3 needle valve. Cleaned, back together, no problem.

Fast forward to current (55k). Go to leave for work one morning, once again, pouring gas from the bowl overflow line. Pulled the carbs, carefully cleaned and inspected jets, emulsion tubes, needle valves, slides, butterflies, and passages. Nothing. No dirt, no grooves in the needle tips, nothing. Checked the float levels (good), and inspected around the base of the bowl overflow tubes. All good. Put the bike halfway together, balance the carbs, set the idle mixtures, all is well during this time. Put the tank back on and voila, leaking from the overflow line again.

I really do not want to pull the carbs again, nor do I want to push this thing off a cliff.

Got any ideas?
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Offline tweeter55

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #1 on: January 01, 2015, 02:51:37 PM »
Is it possible the float is flooded?
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Offline gregman_1

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #2 on: January 01, 2015, 03:30:42 PM »
Quote from: tweeter55 on January 01, 2015, 02:51:37 PM
Is it possible the float is flooded?

Checked all 4 floats for leaks and cracks, no dice.
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Offline tweeter55

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #3 on: January 01, 2015, 04:57:53 PM »
You may continue  :banghead: :banghead: :banghead:
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Over the years:       1972 Harley Rapido
1972 Suzuki T350R  1979 BMW R100RT
1987 Honda Helix.    2006 Kawasaki Concours

Offline gregman_1

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #4 on: January 01, 2015, 07:28:35 PM »
Quote from: tweeter55 on January 01, 2015, 04:57:53 PM
You may continue  :banghead: :banghead: :banghead:

Yep, still working on it as we speak (well, taking a break right now).
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2005 Concours-"The Other Woman"
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Offline Rick Hall

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #5 on: January 01, 2015, 07:34:39 PM »
If gas is puking out an overflow, that means the needle and seat is leaking, as well as the petcock is NOT shutting off.
Fix the needle and seat. But more importantly fix the petcock.

Rick
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Offline gregman_1

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #6 on: January 02, 2015, 05:28:34 AM »
Quote from: Rick Hall on January 01, 2015, 07:34:39 PM
If gas is puking out an overflow, that means the needle and seat is leaking, as well as the petcock is NOT shutting off.
Fix the needle and seat. But more importantly fix the petcock.

Rick
It only leaks with the bike running or the petcock in "PRIME."  The petcock is shutting off normally in "ON" or "RESERVE."
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Offline Mettler1

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #7 on: January 02, 2015, 10:50:28 PM »
  My guess is a bad float needle. If it doesn't over flow when the engine is off it means the petcock is good. You have a bad needle valve or dirt holding it open. maybe even a bad float.
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Offline Summit670

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #8 on: January 03, 2015, 08:22:47 AM »
Can you disconnect the overflow tube structure enough so that you can see which carb is leaking?  Then you can focus on that carb.

Also, it would be good to connect the tank to the carbs before you install carbs, like on the bench, to see if still leaking.  I'd make sure there is at least 4 gal of fuel in tank, or more, to ensure there is plenty of fuel pressure to put the carb to the test. 
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Offline Daytona_Mike

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #9 on: January 03, 2015, 09:09:15 AM »
A couple of things for you to try. It may work it may not. Most of the time it works for me.
Do you have a full tank of gas?  If so try half a tank and go for a  spirited ride and try to do a few WOT runs and it will clear out. Make sure you dont have a split air box other wise  debris gets in the carbs. Your filter screen in the gas tank maybe deformed  enough to the point of not being able to filter.
We are so glad you have overflow tubes.  :)  One trick you can try is to drain the bowls  and blow compressed air (not too high a pressure- low pressure) into the vent tubes and that might blow any debris past the seat and needle. This trick can save you from pulling the carbs. Refill and drain the bowls checking for debris and repeat if not clean. I wonder if the tank vent line is pinched.
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Offline Steve in Sunny Fla

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #10 on: January 03, 2015, 05:25:24 PM »
there's been some good advise so far. If it were me, and I yhink most of these things have already been mentioned, I'd 1) locate which carb it is 2) pull the carbs 3) polish the needle seat 4) refill on the bench and see if it' still leaking. If that doesn't do it, you need to get creative, looking hard at things like float height, needle tips under magnification, checking floats again, etc. Every once in a while I get a problem child, and you just have to peck away at it till it seals up. good luck, Steve
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Offline Furbo

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #11 on: January 08, 2015, 02:46:00 AM »
Needles are cheap. Replace them all.
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Offline kzz1king

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Re: Carb overflow lines dripping gas! Help! SISF?
« Reply #12 on: January 08, 2015, 07:14:38 AM »
All good advice. The one that stands out to me is TEST THEM ON THE BENCH! Have em rightbefore they go back in.good luck.
Wayne
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