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.