400ex fuel help

[440exridered]

I have a 01 440ex. when i do hill climbs or get the front tires off the ground, i lose all power, hit the throttle and it fails flat on it face. i checked the shut off valve and no problems. i also tore apart the carb. and cleaned and it still does it. but when i am flat ground, there is no problems. Also, has anybody heard any thing on the 500 kit that fours stroke tech has out. please help me if anybody can.

[Wheelie]

Check all the vents/overflow vents on the carb.

[aDviSol2y]

If you have a K&N with outerwears, take the outerwears off. It may be old, worn and clogged. Had this happen to me and it took me weeks to figure it out!