Rejetting 400ex, Just picked up an 07 400EX. . I took out
Rejetting 400ex, Just picked up an 07 400EX. . I took out the old 148 main and put in a 155 because I'm running an exhaust on there. com'' Description: Removing the choke plate to increase airflow. I have a feeling that the carb needs taken apart and cleaned. It runs just fine with the choke on full but dies when ~~Carb Jetting Guide~~ This is a step-by-step procedure for re-jetting a carburetor, in this case it is the stock Mikuni BSR36 SS carb on the Just picked up a 2000 400ex all stock last week and have done all the maintenance work on it. I am 100% positive that I am the 3rd owner of this machine. talk to the guy that had it before me and he said it idled in the summer and that he thinks its bad All Activity Home Forums ATV / UTV Make/Model Specific Sport ATV gearing on 400ex Facebook Twitter Youtube Instagram Pinterest Newsletter Honda 400EX Top Speed & Acceleration So how fast could the 400EX go flat out? Stock 400EX top speed is around 72 MPH on a flat surface. You’ll need to. I am new to this forum and in need of desperate help.