Go on bike bandit and take a look at the parts fiche of the 400ex carb to see if you have installed the accelerator pump spring in the right place. You say you put it up in carb , it shows between the rubber plunger and the bottom bowl of accelerator pump. Sometimes the shaft of plunger wears and changes timing of the pump spray and has to be rebuilt. I thought they were adjustable but apparently only the ones on the 450’s. Have you tried punching the throttle not running with intake tube off to look in back side of carb and see if it spraying or you can pull carb bowl off and push the plunger rod and see if it sprays. Be careful the spray can go quite a distance and in yours eyes if pointed wrong direction

Parks1181 have you had any luck or decide to take to a shop.

thank you everyone for your responses! I’m very sorry I haven’t gotten back to most of you for your last bits of advice as I actually dropped off the atv at a local shop that Has some 5 Star reviews and my friends recommended them. They are charging me around 250-300 was the quoting price for rebuilding and cleaning the carb, cleaning air box, air filter, Intake boot, cleaning the tank and the pet ****, jetting it and tuning it for that quote seems like a can’t beat price in my opinion. Haven’t heard back from how they are doing with it I just know he’s got it up on the lift as per yesterday since I went to his shop to drop off a part. And he hadnt torn into it too much yet. But hopefully he gets her running nicely. And as for me not responding to anyone’s responses I’m greatly sorry because you’ve all been a great help and I appreciate all your effort. I’ve been SLAMMED with 12 hour work days 7 days a week the last 2 weeks but that means more money for quad parts!!!! And Lt granddad thank you for asking if I’ve gotten any progress on it! Hopefully should have it back around Monday if not sometime next week!

Finally got my atv back and she runs great after they made their adjustments! So the only thing left to do now is replace the bearing carrier since the bearings are SHOT.. got all the way to removing the axel last night only to find the hex screws that hold the old carrier in are completely stripped. So I ordered 4 new screws should be here Friday. I’ll probably just use the easy-out tool to get them out when the screws come. For right now letting them soak in some special de-greaser that’s used on jets! My dads friend is a jet mechanic and he has some SERIOUS STUFF!!! Works great. I used it to break lose the axel nuts and worked like a charm after a lot of elbow grease