Ok I have a 2004 300EX. I have owned since it was new. It sat for about 6 years, and I’m now fixing it back up for my son. (Go faster Mods) are, fmf full exhaust, UNI air filter, custom vented air box, procom cdi box, 14/36 sprockets, and a dynojet jet kit. I set the jetting up exactly as the instructions said, needle on 4th groove, and 128 main, mixture screw 3 turns out. The bike has a mid throttle bog/hesitation, after a second it clears up and runs great on top. Idles fine, low and top end fine. I’ve moved the needle up and down, changed the mains up and down, and it still has the bog. When the settings where to dynojet specs, the plug was a perfect tan color. I don’t understand. Any ideas?

I will definently get a compression check and call dynojet. I hate not figuring things out in my own, so i messed with it some more today, and I now have it where it only has the bog at about 3/4 throttle in 1st and 2nd gear. Only hesitates for a half a second, then clears up and hauls a$$ the rest of the way to top speed without flaw. That is also weird. Seems like if it was jetting, it would do it in every gear no matter what. Am I right or wrong?

Thanks for all the help fellas!...This site sucks!

Have you got it fixed yet? I had issues on my Honda rancher carb and tried rebuilding it in adjusting everything but I finally just had to buy a new carburetor .