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Discussion Starter · #1 ·
Hi everyone. I did a search and could not find this problem previously addressed. I have a strange problem and was hoping someone might have an idea what's going on. I have a 1982 CX500. When my petcock is either on or on reserve and my bike is not running gas pours out of a little hose at the bottom of my bike. It doesn't do this when the bike is running. But as soon as I turn it off whoosh. I drained almost an entire tank of gas onto my driveway because I forgot to shut the fuel off. My first thought is sticky floats but I'm not sure if the "vacuum petcock" might be the problem. Has anyone ever experienced this problem before? Any help will be greatly appreciated. Thank you.
 

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Rick, if the overflow tube was cracked, it would also leak when the bike was running. I think when the bike is running, it is using enough fuel to keep the float bowl from overflowing.



I think you may have a sticky float or dirt in the float needle valve,,if you trace the hose back you will see which carb it goes to and which carb is leaking.

If the hose does not go to the carbs it may go to the petcock.



The petcock is not working properly or fuel would not leak past it when the engine is not running.



Once you find out which hose is leaking it will help pinpoint the problem.
 

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float valves stuck. tap it with a rubber hammer and it will stop.


I think Rickbert went through this not too long ago, and it might be best to drop the bowl of the offending carb, or both for that matter, and clean and polish the port the needle rides in with some 0000 wool, also inspect the needle, its tip, etc.
 

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Before you drop the bowls it might be worth a try opening the floatbowl drain and tapping the floatbowl with a screwdriver handle or similar while the fuel is running through. Sometimes you get lucky and this flushes out the offending crud.
 

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Discussion Starter · #9 ·
Before you drop the bowls it might be worth a try opening the floatbowl drain and tapping the floatbowl with a screwdriver handle or similar while the fuel is running through. Sometimes you get lucky and this flushes out the offending crud.


Well that's awfully non-invasive and definitely worth a try so I will try that first. Thanks.
 

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Discussion Starter · #11 ·
Ok so I traced the line that was leaking gas and it does not go to a carb, it goes to the petcock. So now I'm really confused. I don't understand why the petcock would have a line like that in the first place. Is it supposed to hook up to the carb somewhere? Could it be like a vent so air can displace the fuel in the tank? Can I just position it higher than the tank and be OK or do I need to rebuild the petcock. This thing is really weird and unlike any other bike I have ever owned.
 

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You have a problem with the petcock. The petcock has a diaphragm in it, when there is vacuum from the engine it allows fuel to flow to the carbs. When the engine is not running, fuel should not be able to flow from the petcock.



If there is a hole in the fuel valve gas can leak through it and out the vent hose.



You can get a rebuild kit or some people have modified the petcock to act as a manual one.



See this thread.
 

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Discussion Starter · #13 ·
I think I really screwed the pooch now. I gave each of my carb a tap to see what that would do and it didn;t seem to do anything at first. But about half way through my 30 miles drive home my bike would no longer idle and seemed not to be getting gas. So I'm thinking I should pull the plugs and run some fuel through as instructed above. Does that sound right?



Again thanks for all the help. It is greatly appreciated.
 

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That could also be because the petcock is not working properly.
 

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Discussion Starter · #16 ·
So I took apart the petcock and the diaphragm was wasted. So wasted that it can't even be used as a seal. I'll pick up some o-rings today and put it back together tonight. Thanks for all the help.
 

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I seem to be having a similar issue with my bike. It leaked a little upon standing after riding when I got it, but today it was pouring steadily out of the tubes (not sure if it's the carbs or the petcock). I was filling up my tank, forgot to turn the petcock to off, and noticed I was standing in a puddle of gas after. My question is this...would a bike mechanic at a local shop be able to fix this issue or does maintenance on these bikes need to be learned and done by the owner? I'm sure I could figure out the above, but I would feel much better knowing a professional was taking care of it. I'm pretty good at taking things apart but putting them back together can get a little tricky. I've done it with refrigerators before, but then again I've never been on top of a fridge going 55+ mph.
 
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