Yesterday was out riding, second tank of gas on top end rebuild, an if you stayed wot for to long few seconds it would act like it ran out of fuel. then 2 hours later it got where it would die an be real hard to start. just turns over forever. full yosi exhaust, stock carb open air box uni filter, 170main, 42 pilot. 500 elevation or so. went to start it today an it wouldnt start but i didnt really try to hard

 

Wide open throttle on a newly rebuilt engine is asking for trouble. However, you may just have disturbed sediment when you had the tank off, which has come through and blocked the carb. Clean it out.