Hey i need some opinions!!!!

[CrAzY400exRiDeR]

Hey ive been lookin into a big bore kit for my 05 400ex. what kind of bore kit should i use???? would it mess up my bike? is it a smart thing to do? Please answer this ......

Crazy400exRider

[400exridin121]

from what ive heard a 440 decrease reliability in many cases. The 416 is the most used and gives way more punch than stock ,or the 426 are both good just my $.02

[CHEVYZ]

Skip the big bore until you are running a "well built" stock bore engine, or unless you plan on doing a deal of work with the bore. It isn't worth it to just do the bore alone IMO.

For reliability, it is all how you build it. I have seen 416s that can't stay together and some that last for years. Same with all the other bores. Keep in mind that if you to build a reliable engine, so you are gonna want to go with HD studs, timing chain, etc. to keep it together.

[250x_kyle]

a wiseco or je 426 with, hot cams stage 2, heavy duty valves ,and valve spring. a heavy duty cam chain, sparks timing advanement key, an air filter and slip on would give u alot of power when jetted right. and if ur worried about it getting messed up put some heavy duty cyclinder studs on it