i just got a wb eseries pipe pro meg put on and got 8 one inch holes drilled in the airbox lid.... k&n filter and the holes are plugged..... i got it done at the honda shop.... they put a 170 main jet in and it cuts out when im running 3/4 to full throttle i know its the main jet but i dunno how to get into it... and i really dont wanna take the carb apart any help or solutions would be greatly appreciated.... thanx

 

i ran a 155-160 w/ my w.b. pipe but i had a different carb

 

Loosen up your carb from the air and intake boots, and then just turn your carb so the bottom is easier to get at. You will notice a large 17mm (I believe) nut. Once you take that off you will see a brass hexagonal jet in it. It will be the only item that can be accessed easily after you take that nut off. If you read the asks Sparks Racing on atvscene.com, you will see they recommend a main jet of 152 for 400Exs with bolt on items. So you might want to give that a try. That is what I run for a long time on mine with a Sparks exhaust.

Adam Smith

99 400EX

 

Drop down one jet size at a time and test. Example: put a 168 main in and check to see if it skips. If it does, drop down to a 165, then 162, then 160, 158, 155... Once you have a main jet in that doesn't skip, that's the correct one for that altitude, temp.

ogre

 

You cannot do any intelligent rejetting until you know what YOUR engine is telling you in relation to YOUR elevation and temperature. To know what it is telling you, you need to do a test/plug read to see whether your jetting is lean or fat. Only then can you really know which way to go.