hey i just bought a 2001 400ex w/ white bros. pipe, but when i nail it in 3rd it will die and come back, this also happens in every gear, so i know and knew the guy didnt jet it. What size jet do u guys use on ur 400's?

 

I would probaly go with a 155, if thats all he has done to it.

 

yep, try a 155 mainjet. also, clean the carb out while your at it.

 

ok thanks guys