ok on my 400ex I am running an HMF s/o with the welds ground out of the head pipe, an XR cam, sparks flywheel key and I have 4 1" holes in the air box lid. oh and I'm running a #40 pilot jet and a #160 main. the motor runs great except when I'm in 5th gear wide open. it still runs good but it don't seem to pick up speed like it should. it doesn't miss or backfire at any point in the rpms. just when it's wide open in high gear you can still feel it pulling but it doesn't feel like it has any power. I hope that makes sense. I think I'm too rich on the main jet but I wanted someone else's opinion before I mess with it again. THANKS [img]i/expressions/face-icon-small-wink.gif[/img]

 

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sickMojave, this may sound weird, but I just did my 400ex and I noticed something different but it took a while to figure it out. I lost alot of low end grunt when I did all the mods, I was thinking it was my jetting as well and worked with it half a day and noticed worse results. I'm almost 99% sure it's the low end grunt/power I lost with the mods I'm going to go to a 40 tooth rear sproket to see what happens next, if that doesn't do it I'm going to have to go to the big bore kit to bring back the torque I lost with the cam and head work.