my buddy has a '98 yz400 that was running fine until it sat for about 6 months and now it won't run without the choke on. i have cleaned the carb very well and the jets were clogged but now they are all good, cleaned and changed the needle and filter. it starts first kick on the choke and runs great choked but as soon as you turn off the choke it starts popping and then dies and will not idle without the choke on. it has a full exhaust, powernow, and a 178 main. i think it is running out of fuel but i am stumped, any ideas would help. thanks!!!