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Discussion Starter · #1 ·
Hey guys,

So I recently purchased a 2009 EX500 (~5000 miles), and I've put in new spark plugs, cleaned the carbs, changed the oil, put a new oil filter in, put seafoam in the gas tank, all that wonderful stuff.

So yesterday, after putting in the new spark plugs we got it running, but one of the cylinders didn't seem to be turning over. Both mufflers were working it appeared, however the left exhaust pipe near the engine was not getting warm (the right one was).

I really don't think its the spark plugs because we checked to see that they were working properly before we put them in by grounding them against a bolt and pushing the starter button. And we seem to be getting a decent amount of compression in that cylinder as well. I'm kind of stuck as to what could be wrong. Any help is appreciated!
 

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Mexican Hard Shell Taco
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You checked for spark, you've got compression, that means you're missing fuel. Problem is the carburetor for that cylinder.
 

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Discussion Starter · #3 · (Edited)
You checked for spark, you've got compression, that means you're missing fuel. Problem is the carburetor for that cylinder.
We cleaned out both carburetors before we did anything else. Shot them with carb cleaner and made sure all the jets were clean and open. When we turned the little drain plug on the side of the carburetor fuel ran out the opening. So we know the carburetor is getting fuel. That doesn't necessarily mean its getting into the cylinder though correct?
 

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a quick way to check, is spray some carb clean into that cylinder.
that should make it fire for a bit, if it is not getting fuel.
 

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If one cylinder turns and another does not you have a very serious problem. I am sure that is not what you meant.

Ok, if you know fuel is flowing the next step in my mind will be to check if you a spark. Without getting zapped (I did once) or worse electrocuted, check if there is a spark coming from the plug when the bike is running. If no spark, measure the resistance and continuity on the wire. If that checks ok then inspect the ignition coil. If that checks then keep digging deeper to inspect the CDI or pulse generator.

 

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Mexican Hard Shell Taco
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We cleaned out both carburetors before we did anything else. Shot them with carb cleaner and made sure all the jets were clean and open. When we turned the little drain plug on the side of the carburetor fuel ran out the opening. So we know the carburetor is getting fuel. That doesn't necessarily mean its getting into the cylinder though correct?
That just means that there is fuel in the carb bowl, the pilot jet or a small passage can be clogged and it will not run.

Spay starter fluid on that carb, and if it does run, then you've narrowed down the problem to that particular carb.

Are you 100% you are getting spark on that plug? Another possibility is that you're getting too much fuel, is it fouling that plug?
 

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Supersquid
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If its getting fuel check that a valve is not stuck closed sounds unlikely for the year but one day my 06 zx6 did it out of the blue and I checked everything, spark fuel compression, timing.
 

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Discussion Starter · #8 ·
I"m 100% positive that the spark plugs are working. We made sure we had a good solid ground when we turned the starter on. We're going to run a compression test tomorrow on the cylinder to make sure that that is working.

If that is working we'll go back and check the carb, maybe spray that carb cleaner in like you suggested. I'll also probably try to swap the ignition coils and spark plugs from side to side to see if anything changes. Thank you for all the feedback. I'll let you know tomorrow.
 

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Discussion Starter · #9 ·
Okeydokey guys, we did a compression test yesterday and both cylinders seemed to be putting out about 180 PSI, so I'm pretty sure that's not the problem. Also took off the exhaust to check for any blockages. Those were fine too.

While we had the exhaust off we tried to turn the engine over to see if it would catch. A huge amount of fuel gushed out the left cylinder exhaust port when we turned the engine over. Could it be that the cylinder was just getting flooded?

Also, we checked the spark plugs again. The one on the left seemed to have lost its spark. The thing was literally brand new, but it seems to have shorted out. So, as far as I can see its probably the carburetor or the spark plugs are failing again. I also may just try swapping the ignition coils.
 
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