Help with Fuel Leak

[Wagonpeddler]

Decided to take the bike out from storage....1981 Custom that I have owned since 1984. Started and ran fine, but noticed fuel running down the bottom of the outside carb. gear shift side. Appears that the leak is originating from somwhere between those two carbs, and only leaks while the engine is running. Can't really see where. Stopping engine with the petcock on, and the leak stops. Carbs were drained for winter storage.
Appreciate any help...removing carbs probably above my comfort level.
Thank you.

[TOOLS1]

Since you have a vacuum operated petcock, it is only going to leak with the engine running. Since you say it is running down the side of the carb, it sounds like the fuel line its self, or an O-ring on the fuel tube that connects the two carbs.
TOOLS

[Wagonpeddler]

Thank you so much. Can you recommend how to proceed? Am I able to check this by removing the fuel tank? 

 Best,

    Ken

 

 

On 03/16/15, TOOLS1 [via Honda CB750'S]<[hidden email]> wrote:

 

Since you have a vacuum operated petcock, it is only going to leak with the engine running. Since you say it is running down the side of the carb, it sounds like the fuel line its self, or an O-ring on the fuel tube that connects the two carbs.
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[Wagonpeddler]

Best to remove the fuel tank to check this?
Thank you.

[TOOLS1]

Yes. Remove the fuel tank and look it over. The leak must be found, and repaired. You might need to find another gas tank, like one off a lawn mower to temporally hook up, so you can have fuel going to the carb, so you will be able to see where it is coming from.
TOOLS

[Wagonpeddler]

That makes sense....I'll try to rig up something. Any chance the float is stuck, and causing the fuel to back up?
Thanks.

[shinyribs]

If it appears to be coming from between the carbs it may the o-rings that seal the fuel transfer tubes. You should be able to reach then while still installed on the bike and see if they feel loose. I wouldn't try to twist them, as this may create a leak you don't already have, but you can try to wiggle them and see if they are still nice and tight.


The parts listed as #1
 edit: noticed they have several parts listed as #1the o-rings at the red arrows.



A stuck float / float valve can let it flood, but it should run out of the overflow nipples on the bottom of the bowls. Unless they are stopped up, of course. But if you can drain fuel from them, then you know thy aren't. Hope this helps.

[Wagonpeddler]

Thank you for that suggestion...if so, looks like a relatively easy fix. I downloaded a Honda Carb Rebuilding manual and was overwhelmed at even thinking of doing all that work....hope nothing else is needed. I have owned this bike for around 30 years, and all I have ever done is change oil, tires, and other regular maintenance. Never had an issue with anything. Guess something is bound to go wrong after all that time.
Again, appreciate your advice. Will let you know what happens.

[Wagonpeddler]

Removed the tank...difficult to see exactly what you are referring to, Shiny. Not much room to work either. Once I can find some kind of tank to hook up, I will get you an update.
Thanks.

[shinyribs]

Look at your stub that you hook your fuel line to. It runs down in between carbs 1& 2 and you will see that it is actually a tee fitting. That's your , I guess you would call, fuel supply tube. Then, there will be a tube connecting between each carb all the way across the rack: fuel transfer tubes.

There are actually two sets of transfer tubes that you will see. The larger is fuel, the smaller is for the accel pump circuit.


But....your carbs haven't been opened in 30 years?!?!?! That's awesome!!! But that is some old o-rings,too.

Found a pic on my computer. Those tubes are buried much worse than I remembered (red arrows). So my advice was probably poppycock.

[Wagonpeddler]

Indeed...lots of tubes. Larger one...guess that is the main line from the petcock. Really hard to see exactly where it goes. part ends up (I think) on the carb with the accel pump on the rear brake pedal side. Your carbs 1 & 2...on the gearshift side? Just trying to figure the orientation from your photo. Still need to find where the leak is coming from before the next step. Perhaps a job for a more qualified individual.
Thanks again.

[rich]

Mine started leaking like that about three years ago. I found that if I never turn the fuel off that the O-rings stay wet and don't dry out and shrink. I think you have a vacuum operated petcock so that won't work for you.

[shinyribs]

That pic is from the engine side. Confusing, sorry, I know.lol

 Your accel pump is on carb #2. Carbs as seated are LEFT 1-2-3-4 RIGHT.

[Wagonpeddler]

I had the fuel tank inside rust treated several years ago. The tank was off the bike and dry for a few weeks. When I installed it afterwards, and turned the fuel valve on, gas started leaking around the petcock. After sitting for a day or so, the leak stopped. Guess the dried out seals expanded and stopped leaking. Haven't had a problem since.

[Wagonpeddler]

Thinking about the previous issue with the shut-off seals...I put the tank back on and tried running the bike again. The fuel leak has stopped. Let it run for a while with the shut-off on and off....and no fuel leaking. A lucky break for me, indeed!
Thanks again for all your assistance. Really appreciated.

[shinyribs]

Self healing motorcycle? Or maybe Wagonpeddler just has the magic touch.


Thirty years and counting...

[Wagonpeddler]

Thanks for the vote of confidence. Usually, anything I touch turns to __it. Guess this was the exception.