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I recently repainted my candy red '85 Rebel 250 matte black with plasti dip. This involved removing the front and rear fenders along with the gas tank and repainted them.

After painting and reassembling, the bike just wouldn't start! As soon as I tipped it over to put it back into the garage, the carb overflow tube spewed out gas. First thought was that float was stuck, so I removed and cleaned the carb and replaced the float needle seeing as it was a little funny.

Today I put the cleaned carb and the gas tank back on and tried to start it. Life! The bike would roughly idle with full choke and eventually I was able to take it around the block. Put it back into garage and an hour later went to clean up and noticed gas everywhere with fuel flowing out of overflow. Left the petcock on reserve (near empty gas tank) and then shut it off. WHY?!

TL;DR
Bike wouldn't start, overflow tube spewing, cleaned carb, overflow tube still spewing, why?
 

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Discussion Starter #4
The carb was actually brought to a local Honda repair shop in which they cleaned, and replaced gaskets and the float needle so I am going to safely assume the float is at the right height.
 

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If the petcock has "prime" position, check to make sure it is not leaking out that port.

Turn the gas to on and Pull the prime hose off the carb and see if there's gas in the line....leave the hose in a container and see if gas ever leaks out...a faulty petcock will cause gas to come out the overflow tube.
 

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The float determines the level of fuel in the carb and should shut it off when full, so if the level is too high, that should be the culprit.
 

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The float determines the level of fuel in the carb and should shut it off when full, so if the level is too high, that should be the culprit.

Could be, but...if the prime port on the petcock is leaking, fuel will flow directly into the carb bypassing the float totally...even with the float working properly, a leaking prime port will cause a fuel overflow.

And if the prime port leaks fuel while the bike is running, then that vaccuum line is pulling gas straight into that carb...causing high idle and bogging issues when you open the throttle.

Start with the petcock, then investigate the carb.
 

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Could be, but...if the prime port on the petcock is leaking, fuel will flow directly into the carb bypassing the float totally...even with the float working properly, a leaking prime port will cause a fuel overflow.

And if the prime port leaks fuel while the bike is running, then that vaccuum line is pulling gas straight into that carb...causing high idle and bogging issues when you open the throttle.

Start with the petcock, then investigate the carb.
The prime position shouldn't bypass the float valve. The carb would only fill if the float valve was open. (Carb bowl empty or malfunctioning float valve)

Leaking seals in the fuel valve could potentially allow fuel to be pulled into the vacuum line.
 

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The prime position shouldn't bypass the float valve. The carb would only fill if the float valve was open. (Carb bowl empty or malfunctioning float valve)

Leaking seals in the fuel valve could potentially allow fuel to be pulled into the vacuum line.
Dodsfall... What he's saying is somewhat true, but wrong. The prime position is not the problem. But if a vacuum operated petcock develops a hole in the diaphram, fuel will be pulled into the vacuum port.Thus causing a floaded condition to whichever cylinder is affected. It is rare, but it does happen. However, it would not cause the symptoms described here. And it is easy to diagnosis... You are right Dodsfall. The prime position would not be the cause.
 

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Um, just curious... but why would you lay the bike on its side to get it thru a garage door? Do you realize that doing that would cause the carb to leak fuel? Then you pulled the carb and "fixed" it? It probably wasn't in need of repair. Motorcycles were not designed to be laid on their side... If they are laid on their side, they tend to leak fluids. Sounds to me like some debris got caught up in your carb float valve. Causing it to not shut off completely.
 

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Take the carb back to the rebuilder. Float is either sinking or the needle is sticking.
Yes, and adding to the float sinking problem,there is a quick test for that. You can shake a float to discover if it is leaking. However when the float is manufactured some metal from the solder can get inside and rattle around sounding the same as a bit of fluid--at least to my old ears. Of course I am talking about old school brass barrel type floats here

So just do the rifle scope test for water tightness.. Immerse the float in a container of hot tap water. The air inside the leaky float will heat up and expand --making bubbles. I just had a float from a 1970CL175 fail this test:frown: Just because a mechanic cleaned your carbs is no guarantee that he checked for a sinking float.

Whenever I clean a carb of unknown history,replacing the needle and seat is something I do as a matter of course. [Honda calls this assembly a float valve] The little float needle usually contains a spring loaded plunger that can wear out or get gummed up and besides that,the needle itself can and will wear at the tip. Cheap insurance to replace them as a unit
 
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