Author Topic: Fuel Leak - Need to confirm my research and go-forward plan  (Read 188 times)

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Offline Burgundy XXXX

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Fuel Leak - Need to confirm my research and go-forward plan
« on: April 08, 2019, 12:26:08 am »
Howdy folks, I'm new to the forum and need some help. Before I explain the situation, a couple of quick notes: first, I hope to join as a Real Member soon, but can't justify it until I'm actually riding my bike; second, my username is not meant to offend, it simply describes my ride ('97 Concours in burgundy with a Zephyr [ZR1100] front end).

Here's the background: I bought my Concours about 6 months ago. I got it for $300 because it didn't run. A wire brush on the clutch lockout switch contacts and some dielectric grease got it to fire, but there were a bunch of other issues that needed to be addressed before she was roadworthy. Today, for the very first time, I got the ol' girl running on gas (what a great sound!).  Unfortunately, I quickly noticed the infamous gas leak--it was dripping quite quickly from the carburetors. I couldn't find the exact source, especially with the volume coming out. I shut the bike off after I noticed the leak and didn't start it again. I've read a lot about hydrolock and the petcock/needle valve issues, so I know I need to address those. My specific question now is, how much do I really need to plan on doing to fix the issue I'm facing? In advance, I understand that I didn't give enough information to decide for certain, which is why I'm appealing to the vast experience and wisdom contained here in COG. So, here's what I'm thinking of doing:

1. Pull the plugs
2. Turn the engine over slowly to expel any gas in the cylinders
3. Perform hydrolock test
4. Drain the oil, since it's likely got gas in it
5. Rebuild the petcock
6. Pull the carbs, rebuild them

Is the carb rebuild necessary? I assume so, since everyone says that both the needle valves and the petcock have to fail for them to overflow. Also, it sure looked like the leak was somewhere in the carbs themselves. But I'm in a bit of a time and budget crunch here and want to make sure I'm spending both time and money wisely. I know Steve's rebuild-and-overflow-tube service is the ideal answer here, but I just can't afford it right now.

If (when) I do rebuild the carbs, how extensive of a rebuild should I do? Is Murph's basic $70 kit (https://www.murphskits.com/product_info.php?cPath=1_94&products_id=130&osCsid=UeP-1JgatkDagRbrDnnEQ1) sufficient or will I need other parts as well? I'm curious about the fuel rail o-ring kit--it seems like cheap insurance. Basically, I'd like to have everything I need available when I pull the carbs out so that I'm not held up waiting for parts.

Is there anything else I need to think about or address? I understand that this topic gets beat to death here, but I've been reading and thinking and calculating for so long with this bike that I'm starting to get analysis paralysis. I need some wise old greybeards to set me straight. In advance, I appreciate any advice anyone's willing to give.

Offline Pbfoot

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #1 on: April 08, 2019, 12:33:55 am »
I believe Steve charges $80 to install overflow tubes if you send him just the bowls. Murphy kit is good. Make sure you remove the caps that cover the pilot screws. Do not screw the pilot screws in too tight on installation.or you will ruin the tips. Gently bottom out the pilot screws and back out 1-1/2 to 2 turns. Pull the fuel line and check to see if the petcock is leaking in the on position. Murphs has a rebuild kit for the petcock as well. Many of us install a Napa 90 degree fuel filter.
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Offline SteveJ.

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #2 on: April 08, 2019, 10:26:00 am »
I believe Steve charges $80 to install overflow tubes if you send him just the bowls. Murphy kit is good. Make sure you remove the caps that cover the pilot screws. Do not screw the pilot screws in too tight on installation.or you will ruin the tips. Gently bottom out the pilot screws and back out 1-1/2 to 2 turns. Pull the fuel line and check to see if the petcock is leaking in the on position. Murphs has a rebuild kit for the petcock as well. Many of us install a Napa 90 degree fuel filter.

+1

I would add that unless you have back up bowls and a drill press don'y even think about doing your own for the bowl drains. A few folks have learned this the hard way.

But do get the overflows. It's kinda like Russian Roulette each time you hit the starter without them.
Yeah, if you want true ram air tuning, you better be willing to ram some air! (SiSF)
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Offline JPD

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #3 on: April 08, 2019, 12:06:33 pm »
If it was overflowing with the bike running the petcock may be good. With the bike running vacuum opens the petcock and just a stuck carb float will cause an over flow. It will over flow all the time if both are bad.
Put the bike on the center stand remove the air filter and put the petcock on prime. You can use a flashlight and small mirror to look for the carb that is leaking. It can help you see in the carbs if the throttle is held wide open. If you do this you must also do the steps to make sure no gas has run into the cylinder. Several years ago I had just one carb leaking and I was able to clear the debris form under the float needle and get it to stop leaking. Last spring the set went to SISF for his full treatment. Over flow tubes will not prevent fuel leaking they will just let you know it happened and will prevent the fuel from running into the cylinders.

Offline Bud

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #4 on: April 08, 2019, 05:57:27 pm »
Also be aware that rebuilding the petcock has had mixed results from those that have done that.  I just buy an OEM petcock and be done with it.
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Offline Burgundy XXXX

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #5 on: April 09, 2019, 01:35:15 am »
Awesome, thanks for all the great tips! I really appreciate the advice. I had the petcock in "on" while the tank was off the bike and it didn't leak, but the fuel level was low enough that I had to switch it to reserve to get the bike to start. Once I pulled the tank back off the bike the petcock continued to leak; I had to switch it back to "on" to stop the flow. So I know the petcock is bad. I should note that the leak continued after I shut off the bike, but took a while to stop even after removing the tank, so it seems like a sure thing that the petcock and carbs are both bad.

I wasn't aware that overflow tubes by themselves were only $80 so I will definitely get that done. I'll take pictures as I work through this and see about posting them up to help out those who come behind. Thanks again for the help!

Offline Bob_C_CT

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Re: Fuel Leak - Need to confirm my research and go-forward plan
« Reply #6 on: April 09, 2019, 10:18:15 am »
Have to ask, are you sure that when you went to reserve and not to the prime position that would let the gas flow freely? Did you move the lever towards the back of the bike?
How clean is your tank? When you went to reserve you are getting whatever is in the lower portion of the tank.
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