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Discussion Starter #1
Ok I have a 2000 Honda 400Ex. I bought it from a guy here in Phoenix,AZ. I rode it around a bit and it was running ok. I go to start it up last week and ride around in the dirt for no more than a half mile and the bike just starts to bog and die. I go home and start tearing into it since now it only turns but doesn't start. It will give me a lil turn over but it quickly dies and doens't idle. So far I've found and changed a fouled spark plug, Confirmed i have nice blue spark when I hit the starter. I took apart the carb two days ago and found no gunk, however I did notice that the main jet was REALLY loose and seemed to just fall out when i started to disasemble. I downloaded a manual and checked valves clearances (they were tight before hand) and made sure they are up to spec. I'm new to quads and I hope I'm not missing something. Any ideas on where to go next? Even the smallest detail will be helpful, I'll also include pics if anyone wants to see something that I'm doing.
 

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Start with a bit more info about your machine. Is it stock? Anything been done to the motor, intake, or exhaust? What is the jetting? Have you checked battery voltage and all of the connections? Have you checked fuel flow from the tank to the carb? There is a filter screen in the tank attached to the petcock. You may want to drain the fuel out of the tank and try to remove the petcock to clean it. Be careful, because the threaded inserts that the screws go into are molded into the plastic tank and may start to spin. If that happens, you will not be able to remove the petcock. There may also be a screen in the brass tube on the carb where the fuel line from the tank attaches. Most likely it has been removed, but check anyways. When you cleaned the carb, did you remove everything that you can, spray it down with carb or brake cleaner and then blow everything out with compressed air? Also, double check the throttle cable adjustment at the carb and idle screw. After you cleaned it, you may not have gotten it all adjusted right, which would not give enough fuel through the slow side to allow it to fire. Those are the places that I would start.
 

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Very good.
Do you have the Honda manual, not the Haynes or Chiltons?
I only buy OEM parts, usually from Partzilla and Rocky Mountain (links to their parts diagrams in my signature block below).
I was gonna suggest rebuilding the carb. I use Shindy carb kits most often, which has all replacement jets but not the starter jet passage plug which sometimes get loose. the OEM gasket kits only have the rubber bits and the starter jet passage plug.
 

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Discussion Starter #5
Start with a bit more info about your machine. Is it stock? Anything been done to the motor, intake, or exhaust? What is the jetting? Have you checked battery voltage and all of the connections? Have you checked fuel flow from the tank to the carb? There is a filter screen in the tank attached to the petcock. You may want to drain the fuel out of the tank and try to remove the petcock to clean it. Be careful, because the threaded inserts that the screws go into are molded into the plastic tank and may start to spin. If that happens, you will not be able to remove the petcock. There may also be a screen in the brass tube on the carb where the fuel line from the tank attaches. Most likely it has been removed, but check anyways. When you cleaned the carb, did you remove everything that you can, spray it down with carb or brake cleaner and then blow everything out with compressed air? Also, double check the throttle cable adjustment at the carb and idle screw. After you cleaned it, you may not have gotten it all adjusted right, which would not give enough fuel through the slow side to allow it to fire. Those are the places that I would start.
Thanks, i have it sorted out now. Turns out the idle screw was adjusted too low.
 

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Discussion Starter #6
Very good.
Do you have the Honda manual, not the Haynes or Chiltons?
I only buy OEM parts, usually from Partzilla and Rocky Mountain (links to their parts diagrams in my signature block below).
I was gonna suggest rebuilding the carb. I use Shindy carb kits most often, which has all replacement jets but not the starter jet passage plug which sometimes get loose. the OEM gasket kits only have the rubber bits and the starter jet passage plug.
Thanks, i have it sorted out now. I do have a Honda OEM manual
 
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