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My bike is a 2006 EX500 recently purchased with 6900 km and I have ridden it for 1400 trouble-free km. It has run perfectly- until now.

Recently installed Oxford Heated Grips, which involved removal of the gas tank and fairing etc. The grips were wired to the battery with no connections to the existing wiring. Only the headlight and indicator connections were detached and reattached.

The gas tank was replaced, fuel lines properly attached, the battery ground wire connected and the bike was fired up. The left cylinder ran but not the right. Smell of unburnt (raw) gas, turned off ignition.

Raw gas is leaking from the right exhaust at muffler connection. The left cylinder has smoke vapour exiting muffler. It is raw gas that has leaked into the hot exhaust

Checked every electrical connection, fuel and air line, nothing out of sorts. Air filter was as expected for the low mileage.

The float bowls were drained- equal amount of fuel from each side and after shut-off the gas did not flow indicating petcock is functioning.

Definitely not an ignition problem. Spark plugs, HT leads and coils were all individually swapped with the same results- right cylinder not firing.

After the float bowls were drained we restarted the bike. Both cylinders were firing for a bit with choke applied and it started to run rough, eventually sitting on the right again. Shut down and gas leaking form the pipes again. Both sides, even tho the left cylinder was firing.

Keep in mind that this bike has only 6900 km. It has been ridden regularly for several months with fine performance, not a hint of trouble, it’s like a new bike. Well maintained and upgraded with new tires, fork springs and mirror extenders.

There is no logical reason for such a radical change in running by simply removing and replacing the gas tank if nothing has been dislodged. Yes, there are some very rare cases of coincidence but I’m sceptical. Sudden catastrophe is unlikely considering the mileage and overall condition of an otherwise great running bike.

???
 

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"by simply removing and replacing the gas tank if nothing has been dislodged"
Sorry, something was dislodged, somewhere. Suggest you look closely at all connections especially right side ignition coil.
 

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There is no logical reason for such a radical change in running by simply removing and replacing the gas tank if nothing has been dislodged. Yes, there are some very rare cases of coincidence but I’m sceptical. Sudden catastrophe is unlikely considering the mileage and overall condition of an otherwise great running bike.

???
I'll bet I have heard this a 100 times. and it is not correct. because if it WAS running perfect and now it is not AFTER some work was done it is almost guaranteed whatever you did caused the issue. now what that was is a mystery as only you know you did exactly. you could start by removing the tank again. disconnecting whatever you connected and then using a remote fuel source (not the tank) see if it runs. you could have just simply pulled a wire off or got a nibble of rubber from the fuel pipe (when fitting it back onto the the petcock) down into the carbs it has been known to disconnect something and then forget to plug it back in. no idea it is all just guesswork until you test everything you did.
 

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Do you KNOW you have spark on the right side? Or are you just assuming you do because you swapped everything? Take the right side plug wire off, stick a screwdriver in the end and then carefully hold the screwdriver so that the exposed metal shank is close to the engine block while the engine is cranking or running. You should see a spark jump from the screwdriver to the block. Not sure about the EX specifically, but most other ignition sources will throw at least a half inch of blue spark. The more orange it is, the weaker it is. Alternately, you could pull the plug and rest it against the block and look for spark there while cranking. Best to close the petcock and drain the carbs before that test. And, not to sound condescending, don't be careless. Fuel + Ignition source = Fire. Fire = Bad. So be careful.

If you don't have spark, back up to whatever feeds the coil for that side. Start checking wires, connections and whatever else you can.

It is also possible that you dislodge some gunk in the fuel system and that's now holding a float open or something similar. I'm not exactly well versed in carburetors so I can't give much more detail than that.

But I would make absolutely sure you have spark to that side before tearing into the fuel system.
 

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Yeah, it's rather simple. If the right plug is wet, it had fuel. If the cylinder has compression and fuel, then it is spark spark spark.
 

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Background: I am a friend of Trapshooter and have been helping him through this. I've been riding for over 50 years and have maintained all my bikes using factory workshop manuals. This isn't my first rodeo.

The bike does not have an electrical problem. We pulled the plug on the misfiring cylinder and checked for spark- it was a healthy blue/white strong spark. We first switched the plugs left to right side- the same result. Then the HT leads were swapped- same again. Then the coils were swapped with no change in running. It can't be ignition, although I admit it could possibly be ignition timing, but very doubtful.

The choke is operating normally with the same amount of travel on either side. The vacuum line to the petcock is clear and no fuel or air lines are pinched or blocked. The petcock is operating correctly: float bowls removed and the fuel does not continue to flow after the bowls were drained. The fuel was clean, no foreign bits or water. The air filter is clean and the offending cylinder has good compression.

I have been leaning to carburation as the source of the problem from the start, the flooding with too much fuel. Reluctance to remove the carbs for an overhaul promted us to reach out to the forum, in case someone else has experienced this and perhaps offer a far simpler answer to the problem.

Thanks for your input.
 

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when you take the plug out of the side that is not working is it wet or dry. if it is dry it points to the carbs. if it is wet it points to the sparks no matter how unlikely that seems. it cannot be the timing this is fixed if it's off both cylinders would not fire. the best way to tackle EX problems is to imagine that you have two single cylinder engines bolted together.

each side has it's own ignition system carb and exhaust fed from the same common source. if there is a problem that effects just one side the issue is on the down side of that common source. if it effects both sides then the common source is the issue.

it is difficult to put it any simpler than than. if you swap over components and the issue is still there on the same cylinder and not transferred to the other one the components are not at fault (but the feed to them could still be) if all the electrics are found to be good it has to be some other issue like the carb on that side. the only way to solve the problem is intensive investigation of all elements on that side.

one other point. the OP said that work was done to install heated grips and they were connected direct to the battery this is not a good idea despite what the instructions may say on the box. the EX is designed to have extra electrical components wired from the fuse box. if you look on the connector to the fuse box you will see two empty ports on the right hand side. one is a direct feed port (for things like alarm) and the other is a aux port ( only live when the ign switch is on) for everything else. a 16amp female spade will push into the port to make connection. and of course because the feed is direct from the box it will be fused automatically.
 

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OK Trapshooter had correctly identified his bikes problem, yet seems reluctant to follow up on it. Too much fuel. well the there are a couple of things that control the flow of fuel. #1 a vacuum operated petcock. allows fuel to flow only when the engine is running.
#2 the float system , a float is attached to a valve to only allow fuel to flow as needed.
#3 the jets 2 both main & pilots. here can be eliminated as they can only get plugged and stop fuel.

There it is Boys & girls, now you know where to look

FOG
 

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Discussion Starter #10
OK Trapshooter had correctly identified his bikes problem, yet seems reluctant to follow up on it. Too much fuel. well the there are a couple of things that control the flow of fuel. #1 a vacuum operated petcock. allows fuel to flow only when the engine is running.
#2 the float system , a float is attached to a valve to only allow fuel to flow as needed.
#3 the jets 2 both main & pilots. here can be eliminated as they can only get plugged and stop fuel.

There it is Boys & girls, now you know where to look

FOG
Thanks FOG was waiting for all the comments to come in and as versys guy said we have eliminated all the potential problems that we could by reading other posts in this forum. Thanks to you and all other people who have answered I have come to the conclusion that it is a carb problem and will be pulling carbs today. Thanks again to all.
 

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Agreed, Fog, I know how vacuum petcocks operate, I had two Concours and dealt with a pinhole in the diaphragm. Jet blockage impedes fuel flow and I think the float might be sticking open to allow a continuous flow of fuel when the bike is running.
Question: can the float valve be accessed from below (remove float bowls) or above without removal of the carbs? Not much space for my large hands in there.
 

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Discussion Starter #12
Thanks again to all who posted. Pulled the carbs, turned out there was a small piece of crud on the needle cleaned everything up, put back together started up and runs just like before. This forum is definitely a god send.
 

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you could have just simply pulled a wire off or got a nibble of rubber from the fuel pipe (when fitting it back onto the petcock) down into the carbs it has been known
post #3 18hrs ago I give up a fuel rail filter would have prevented this. never mind at least you have it fixed.
 

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Bike of that age with as few miles as it has is bound to have gunk in the entire fuel system. Especially in the States. I would advise cleaning and coating the tank as EX tanks are almost wafer thin and the moisture from ethanol-containing gas will rot them out. Petcock, lines, rails, carbs are quite another thing.
 

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Bike of that age with as few miles as it has is bound to have gunk in the entire fuel system. Especially in the States. I would advise cleaning and coating the tank as EX tanks are almost wafer thin and the moisture from ethanol-containing gas will rot them out. Petcock, lines, rails, carbs are quite another thing.
Coating the tank with what and how?
 

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The very tiny bit that was lodged in the float valve seat had the appearance of dried residue, likely a result of fuel evaporation in the float bowl, not foreign matter from a gas pump. The rubber grommets, hoses, induction etc are pliable> this bike is in very good condition. It was just a simple twist of fate that the problem showed up at that time.

The gas tank has no visible interior rust and doesn't need coating, the carbs were clean and unvarnished. The bike runs well and it accelerates, idles and is stumble-free from low rpm. I doubt there's "gunk in the entire fuel system".
 

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"dried residue, likely a result of fuel evaporation in the float bowl" followed by "the carbs were clean and unvarnished" HUH?

so who's to say the "twist of fate" will not happen yet again?
 

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We're confident that the carbs are clean. There is no varnish and the small orifices were clear.

What's to say any bike can't experience what this one did, maybe pick up a tiny bit in the fuel that can cause a problem? That's no reason to fix something that ain't broke or to agonize over the odds of reoccurrence. The bike runs well, idles perfectly and accelerates cleanly from any rpm, as I've stated several times already.

The riding season here is drawing to a close: why tear down a bike that is running perfectly when we can ride now? You seem to want to argue about this: I'd rather go riding. Have a great day.
 

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Argue? No. Discuss? Yes. We ARE in an open thread on the forum here. Simply taking issue with conflicting statements.

Suggestion....when convenient in the future, add the ZX6 rail filter as @yorkie suggested earlier in the thread. They protect tiny debris from migrating into the last entry point of carb inlet. Preventative...if its good enough for the ZX6, I'll submit its good enough for an EX.

Pic from a 250 Ninja...positive proof of effective long term rail filter action.

cody1.jpg
 

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Could be, as you say, a twist of fate but more likely something on the bottom of the tank that got dislodged from removal/installation. I would give it a cleaning myself, if not now then in the off season.
I also believe that any ex500 is old enough now that complete disassembly of the carburetors is a good idea, splitting them apart and replacing fuel and vent rail orings, as well as float needles.
The fuel rail is aluminum and ethanol creates a white corrosion in there, and this gives opportunity to clean it out.
BTW, I've also owned two Connies. Still on my second one in fact. Great bike but a beast to move around.
 
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