i have a 2001 400ex when i am slowing down the quad just shuts down. it will not start unless i rock it back and forth hard then it will start..but shuts down once i slow down. i am thinkin its something in the carb could anybody help what it is.

 

Sounds like the pilot jet is plugged with dirt. Take the carb out and clean it. Take the jets out and make sure they get cleaned too.

 

Once it starts...does it idle with out the choke on?
Check the float level also.