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Discussion Starter · #1 ·
hi guys. got a strange one for you. I have the bike (ex cruiser) mostly rebuilt now so yesterday I tried to check out the work done already (completely re wired it) by fitting battery and starting it up.
carbs leaking for some reason, tapped the bowls in case of a stuck float valve. no difference.
removed the carbs placed on bench (untouched) connected remote tank. no leaks, fuel levels spot on, no issues.
refitted to bike leaking again once the fuel line (same remote tank) connected.
carbs off again back on bench, no leaks. drained them, removed bowls for inspection nothing found checked levels again spot on. back on bike still leaking. head scratching time. any ideas.
going to remove them again today and fit new kits although no idea why this would work the ones in them less than 3 months old.
 

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They are leaking into the cylinder or air box? You’re certain its not a hose connection or boot leak? Raise the remote tank high as or higher than real tank to simulate similar head pressure and check for leaks.
 

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Discussion Starter · #3 ·
the fuel is dripping from the btm of the float bowls only. (typical float seat issues) using the same remote tank, same fuel line, the height of the remote tank is in fact higher when the carbs are on the bench as it is hung from the roof joints, on the bike it's hung from the handlebars so about 3ft lower.
had the float bowls off today, replaced with new, the floats, float valves, spindle hinge and bowl gaskets.
new btm allen screws not wet tested yet. too late for today will check and install tomorrow.
 

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Boneless Pizza
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the fuel is dripping from the btm of the float bowls only. (typical float seat issues) using the same remote tank, same fuel line, the height of the remote tank is in fact higher when the carbs are on the bench as it is hung from the roof joints, on the bike it's hung from the handlebars so about 3ft lower.
had the float bowls off today, replaced with new, the floats, float valves, spindle hinge and bowl gaskets.
new btm allen screws not wet tested yet. too late for today will check and install tomorrow.
Only leak under wet testing?
Uneven bowl mating surface?
Drain screw not fully seated or not right size? Cant remember if these have gaskets or metal washers or not..
Transfer tube / drain tube not obstructed?
 

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2009 Ninja EX500r
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Something is being misses or you need a preist. Good luck!
 

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Discussion Starter · #6 ·
Something is being misses or you need a preist. Good luck!
thanks all "no priest required" just a kick in the pants for not paying attention last time I did the carbs.
the issue was a leak from the fuel rail "O" ring (the short one nearest the the intake) found it by accident while attaching the clear tubing for 6th wet test, pulling on the float bowl to attach the tube fuel started leaking from the joint. push the carbs together leak stops pull apart leaks again.
emptying the carbs and turning them over found two of the screws holding the bottom carb joining bracket were loose. allowing the carbs to part slightly and allow fuel to pass the O ring obviously they had not been torqued down on reassembly.

I presume they had worked loose either by vibration or by tapping the float bowls to seal the perfectly good float valves, by fitting them onto the carb inlets it parted the carbs just enough to weep passed the O ring but on the bench there was enough side pressure to seal it.
separated the carbs fitted new O rings and buttoned it up properly this time all seems good no leaks on or off the bike.
I noticed one thing though, maybe one for Duc that tube on the left side is very short into the carb body the O ring only just goes in far enough to seal. is there another fuel rail of a different design that would fit, allowing the fuel pipe to be more central, or one with a slightly longer left side to get more insertion.
 

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@yorkie in my years doing EX carbs, I've never run across/discovered a substitute fuel rail. In any event, correct sized orings are crucial and do seal quite dependably over the long haul.
 
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