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Fuel Leaking

  • Thread starter Thread starter schatenjager
  • Start date Start date
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schatenjager

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Ok, I searched the forums for the answer to this and couldn't quite find anything that sounded like my problem. I recently had my Carbs rebuilt on a 77 GS750. The petcock was also leaking (the diaphragm was installed wrong) but that is now corrected. Whenever the petcock is set to PRI, RES, or ON (I have an "off" position too), there is a fairly significant fuel leakage coming from the carbs. The fuel looks to be leaking only from the 1 and 2 (the side the shifter is on) carbs. I originally thought that the floats weren't working right and reset those. After the problem persisted I figured that maybe the needles weren't seating correctly so I took the bowls off, manually pushed up the floats and turned on the gas. There doesn't appear to be any leakage coming from the needles themselves. The fuel seems like it's coming from the engine side of the carbs and leaks whether the bowls are on or not, and whether the floats are up or down. With the bowls off, I can start and stop the flow of gas through the needles but this is definitely coming from somewhere else. I was under the impression that gas only entered the carbs through those float needles. With those "closed" there should be no fuel flow at all, right? What am I missing here?

My carbs are VM style so there shouldn't be any O-rings in play here. The other two (3 and 4) don't seem to be having any problems at all. Could it be a bad connection between the 1 and 2 carbs (gas must pass between them as there's only one fuel filler line that serves all four carbs so there must be a pass through)?
 
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Maybe your petcock vacuum line is dumping fuel into the engine? This is a common failure mode for the petcock but it should only effect cylinder #2 I believe. You should be able to check this quite easy by pulling off the vacuume line and messing around with the petcock.

Good luck.
 
The fuel coming down from the tank goes into a distributing tube which runs across the rack of carbs. This tube is joined from one carb to the other by brass or plastic fittings with o-rings on them. It's likely these o-rings were not replaced when they rebuilt your carbs and are leaking. Get a complete set of o-rings from www.cycleorings.com. Take the carbs apart from the rack and pull the connecting fittings (review the carbs cleaning link for detailed instructions). Replace the o-rings.
 
Re: Fuel Leaking

The carbs were not separated when they were rebuilt actually. This seems like the most likely place to find the problem. I would assume that these little o-rings can also be found at an autozone or some similar type place?
 
schatenjager said:
The carbs were not separated when they were rebuilt actually. This seems like the most likely place to find the problem. I would assume that these little o-rings can also be found at an autozone or some similar type place?
Click to expand...

Take the o-rings to your local car parts place and they may be able to match them. Make sure to get gas-proof o-rings (no plumbing supply stuff).

BTW, once you have the carbs apart you will probably need to resync them when you put them back together.
 
Re: Fuel Leaking

yeah, I would think that would be a good idea...lol. It's be just my luck to get a set of O-rings and have them dissolve on me...Thanks!

I swear I'm gonna get this bike running if it kills me...

Actually, it runs now, it's just a little dangerous riding around on top of a puddle of gasoline...
 
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