Newbie question about exhausts and jetting

[BeefySTi]

Hey, very much a n00b here, but I am highly considering an FMF Powercore IV slip-on for my 01 400EX and I am wondering what jets to get for it. Also, properly jetted, what kind of realistic power gains am I looking at over stock? If there is a thread about this, I cannot find it and apologize.


let the flaming begin... haha

[honda400ex2003]

1-2 hp with just that and nothing else in there

150 main

3.5 turns out on the f/a screw

leave the rest alone in the carb.

that is with a lid on also.


check out the stickies for plenty of info on these subjects.



Welcome to the site.

steve

[01boneless]

i have one and it adds power but more noise lol they sound great though i run a 158 main but i have no air box lid and my plug runs light grey to tan color so its pretty good

[BeefySTi]

Hey, thanks a lot guys. I appreciate the advice. I will probably keep the air box lid on for now, I tend to get very muddy when I ride.