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Keep or Sell or Scrap

  • Fix

    Votes: 3 100.0%
  • Sell

    Votes: 0 0.0%
  • Scrap

    Votes: 0 0.0%

  • Total voters
    3
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Discussion Starter #1
Hi all,

I think I might have more of a lemon than Ex-500, It has decided it would dump fuel on the floor, again. I have recently rebuilt the petcock, and was functioning properly, I rebuilt the Carb with new parts, re-installed and the bike was running fine yesterday. Now I got a text from the garage where my bike is stored and it has a puddle of gas underneath. I haven't got a clue where to begin now. At least it is on the floor and not in the crank case again.

1987 if the year matters

Any Ideas?

Thanks,
 

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your poll neglected an option....... Light a match?



馃槅
 

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319 Posts
Fix it....no doubt.

I had a GSX-R 750 that loved to dump fuel into the crankcase. This is back in my novice days when I could just about find the carbs. That bike taught me a lot, and there was a real sense of accomplishment when I fixed the issues.
 

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OP not the 1st, certainly will not be the last to experience this. Combination of fuctioning petcock and properly serviced and set up carbs needed.

"Lemon" pertaining to the EX is not a fair, accurate statement. This condition a known, fixable combination of faults involved.
 

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Discussion Starter #5
So an Update, Turned on the petcock, fuel leak stopped??? Turned off Petcock, Fuel leak still stopped??? Ran like a dream actually took it out for an hours ride totally fine. Came back put a spill tray underneatho_O just in case.

Does anyone have any Ideas?
 

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Is the fuel leak definitely from the petcock, and not the carbs? If so, then the petcock rebuild was not as successful as you would have liked....time to do it again.

Did you rebuild the petcock with a service kit, or just disassemble everything, then clean and rebuild? Make sure the parts are assembled correctly, and that everything is smooth and clean.
 

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Discussion Starter #7
I rebuilt both with new service kits along with cleaning them along them before the install of the new parts. Could this just be some residual fuel in lines from testing and it is overflowing back? It is definitely not coming from the tank as the tank was full and the puddle was at most a litre of fuel(1 quart).
 

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Start with the stupid,easy and free stuff first. Even the best mechanics can make silly mistakes, such as my brother forgetting to re-connect one spark plug after a carb rebuild on a YZF6 and wondering why it wasn't running right.
So, are both float bowl drain screws snugged down properly? Is the main fuel line seated properly on both the petcock and carb? How about the float bowl mounting screws? Are you sure the float bowl gaskets didn't get crooked and pinched? All of those are free to check and cost just some time.

On to your rebuild of the petcock, I'm assuming you got an aftermarket rebuild kit? If so, that may be a problem. In my experience, while the carbs do just fine with aftermarket parts, the petcock really doesn't like them and will only work best with OEM gaskets, particularly the vacuum diaphragm. Aftermarket ones, even from decent quality brands such as K&L, will fail alarmingly fast, though the diaphragm developing a hole or tear won't produce a leak while parked, just while riding and the left side carb will also suck extra fuel through the vacuum port this way too. So, I recommend buying an OEM vacuum diaphragm at the least to save yourself future headache. Possibly the 3 other rubber bits inside the petcock as well, though those aren't as prone to issues if they're aftermarket.
That being said, before you buy anything, there is one more thing to check. Did you reinstall the wavy washer found between the petcock face plate (the thing which has OFF, On and RES stamped on it) and the petcock switch lever? That is an integral part of the system and will cause problems if forgotten. It applies pressure to the switch so it can seal properly against the large round gasket behind it with 4 holes. It also keeps the switch square so the skinny o-ring on the switch itself can seal. Without the wavy spring washer, neither will seal properly and the latter can certainly cause a fuel leak if the switch gets crooked.

All food for thought, let us know how the diagnosis goes.
 

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Discussion Starter #9
Thanks for all the suggestions, I am still at a loss as to why it was leaking but it has now stopped new fuel line is the only item changed. It might have been allowing air into the system causing a leak in the vacuum. Not a problem anymore. I will keep you all posted hopefully it stays all good.
 

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The reverse is actually the case....the system needs the vacuum to suck 'open' the petcock. No vacuum, no fuel. I suspect your old fuel line had a split, hole, degradation of some sort, and the new fuel line fixed the line in the old line.

Either way, glad it's fixed and you're enjoying riding!

And to think you thought about ditching the bike....
 
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