sparks pipe

[cals400ex]

on the sparks website it says run the stock mainjet unless you have your airbox modified for the 400ex. is this what you guys are doing? this does not seem right because i am running a 152 mainjet and don't even have a pipe, just airbox mods.

[Sparks425Ex]

For a Sparks X-6(I have never had an X-4) I use a 160 mj and a 42 piolet jet.

I have a cam, pipe, carb, K and N filter, Modded air box. I prolly should be up a little higher but this is working good for mee.


I would say just jump up to a 158 when you get the pipe.