I have a bone stock 2007 honda 400ex.Bought it new last year.Just looking to give it that little bit more that i did not get by buying a 450.So i am looking to get a bigbore kit for it.Want something that is going to be a reliable purchase and give me the bang for the buck.Don't plan on doing an exaust till next year.Just the kit this year.

 

a big bore kit is useless without a full pipe and filter/no air box cover. but when u do get a pipe and stuff, the 426 or 416 are the most reliable, and have great power, like about as much as a 450 with a pipe, filter stuff. now the best pipe for a 400 is the white bros e series full system.

 

The 400EX is currently one of the best buys on the used ATV market. Now consider a nice 400EX on the used market for $3,500 to $4,000.