1992 yamaha wr500 wont start without pouring gas in?

it will only start if i pour gas in the carb and as soon as that gas is gone it shuts off. I have ckecked the spark plugs, installed new gas, new inline fuel filter good pressuse in lines when i remove them, gas line in good shape.it ran perfect last time i had it out, about 2 years ago, a friend told me there may be a filter in the carb, but i dont know i dont just want to tear the carb off with out just cause.
thanks for any help.