What big bore kit should i get to re-bore my 400ex. Is the CT or Whitebros racing one any good.

 

go to trinityracing.com and get the 465 stroker...thats a big diff.

 

Don't bore over the 400EX, just get a Predator or Raptor if you want more power.

 

its fine to bore out an ex. if someone is having a problem either another part was broke inside or it was installed incorrectly. i have been running a 406 (.040 over) for quite some time and it is extremely reliable along with the 416's. when you get to the 426's your sleeve is getting thin and after that you need to put in a new sleeve. if they are built correclty, you shouldn't have a problem. its not a bad idea to install a larger oil cooler when doing the modifications either. i am building a 426 now and i have been told they are really reliable if you don't go over 11:1. more power will cause more stress as we all know. after 11:1, a heavy duty rod is highly recommended.

 

also, learn how to jet a carb. it is important to know what each of these jets do and where they are located. jetting after modifications will entitle changing the mainjet, pilot jet, adjusting fuel skrew, and changing the clip position on the needle.