help me my 400ex wont run

[brianC400X]

ok here is the deal. It will start and run. but only for a few seconds. If you apply any throttle at all it dies. I just put in a sparks racing timing advance key. Would this cause the problem. Its either carbueration or the timing. I would greatly appreciate any help.

[nakomis0]

Did you adjust the valves after the timing key?
Also do you have a aftermarket cdi box. Becuase for some reason mine wouldnt start with my wb cdi.... i figured the timing was advanced to much..:confused:

[brianC400X]

I adjusted the valves. It has a stock CDI. Ive been playing around with it for hours. Seems to me that the only way it gets fuel is via the accelerator pump. the more times you pump the throttle before you turn the starter the longer it idles. And it will rev just a little then dies immidialt if you move the throttle in just the right way. is there a key part if the carb that can get plugged up and stop the pilot jet and the main jet from getting fuel yet still allow the accelerator pump to squirt. I'm lost I wouldnt be here is i wasnt I could be wrong. When i started this thread I should have been more specific. It will run but only between a few second and maybe 45 seconds. It always dies