headpipe

[alf44]

If I install a highflow headpipe on my 400ex will i need to rejet or mess with airfuel mix? Thanks.:)

[Honda#4]

probably going one up on the main won't hurt anything, but Yes you have to rejet if you are increasing airflow gotta make up the fuel flow by adding a bigger jet which gives more fuel.

What mods are you running, has a lot to do with this to.

[alf44]

Just fmf powercore slip on k&n filter and white bros rev box on this on.

[Honda#4]

42 pilot 155 main and needle on the 4 slot from the top and turn the screw out 3 1/2 turns. Should be good

[alf44]

right on thanks

[Honda#4]

Sure no problem