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Discussion Starter #1
I would like to thank you for help ahead of time as I just started riding last year and have not been able to enjoy my bike this season. I was riding my 2004 ex 500 that I purchased last year and the bike started jerking really bad at any speed when ever I would give it throttle. I then thought it was a good time to rebuild the carburetors since I do not know the maintenance done by the previous owner. After rebuilding the carburetors the bike continued to jerk and since it was close to 12,000 mile i decided to do the valve clearance adjustment. So I then took the carburetors apart and let all of the jets soak in carb cleaner for 48 hours, adjusted the valve clearance, synced the carburetors, replaced the spark plugs, put a new air filter in, changed the bark fluid, changed the engine coolant, put in new clutch spring, rebuilt the petcock and took out the orange piece in the gas tank cover that is know to cause a lock and did a fresh oil change. After completing this i then put the bike back together and it seems to run fine in the range of 0-40 mph then after that die out. In 3rd gear at 60 mph i can barely hold this speed. I have ridden the bike around enough know to pull the plugs and see they are white so i pulled the carburetors again and have run cleaner and mechanics wire though thing and synced the cards again. I still am having the issue of not being able to accelerate and have run out of ideas. I have also checked the petcock by sucking in on the vacuum line and more fuel does flow out. Please help with any thoughts or ideas you may have. Also, i have tried choke while going 60 and that seems to slow the bike down more and have done a compression test and cylinder 1 is at 130 and cylinder 2 is at 133.
 

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Bad plug wires or coil? Mine is doing the exact same thing right now. I found that the coolant pipe that goes to the top of the engine had a bad o ring and is letting water into the spark plug galley which submerged the spark plug wire where it connects to spark plug causing me to run on 1 cylinder, causing jerkieness because the cylinder is coming on and offline.
 

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As suggested check your spark plug caps and coils, though as you say the colour of the plugs is good I'd be looking for an air leak or a missing o-ring in the carbs, also inspect the diaphragm.

Also, did you sync them with a manometer or just manual sync? My first time playing with carb sync I did a bad job and it only really showed up when the bike was hot and at highway speeds, bogging and lurching. Re-synced them with a (homemade) manometer and no more issues.
 

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What was done in carb cleaning that addresses the cleaning out of the pilot chamber?

Soaking the parts in carb cleaner is not adequate. There are canals inside the carberator bodies that need to be addressed. And an order of getting that accomplished.
 

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Yea I thought my carbs were super clean too, but gave up and sent them to Ducatiman and sure enough! Carbs needed more cleaning.
 

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Discussion Starter #7
NewboySF I can't wait to hear back and see how it turns out.

Jackal, I did buy new plug caps but not wires which I will be doing in the next week. I synced the carbs using a homemade manometer and synced the carbs at idle. Please let me know if I should sync above idle I have read many different options on this. I have looked at the diaphragms and there does not seem to be any tears in them. I will like for an air leak this weekend.

FlordiaEX500, I cleaned all the carburetor passages with carb cleaner and ran mechanics wire through each place I could find that had an opening though I could have missed one.
 

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Hey OP, fixed the issue by replacing spark plugs, and spark plug wire and boot. Also put in a new o ring in the coolant hose so it doesn't leak..
 

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Steve16o said:
FlordiaEX500, I cleaned all the carburetor passages with carb cleaner and ran mechanics wire through each place I could find that had an opening though I could have missed one.
You need compressed air and a good solvent to open some of the more obscure passages. They are not all in a straight line. Ever notice those little round plugs on the outside of carbs that look like a BB tapped into a hole? That is a blind passage that no wire will ever clean.
 

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Discussion Starter #10
Thank you guys for all of the suggestions and help. At the end of the day it ended up being the diaphragms. Now it is up and running like new. Thanks again for all the help.
 

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just a though, if you still have the carb vent hose connected, remove it and throw it away, if plugged it will prevent your crabs from drawing mod=re fuel than in them.

FOG
 
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