i just put together my chinagirl and it fired right up however it only ran for about 2 minutes when it just stopped . i was still doing figure 8s in the driveway.. i cannot get the thing to fire up again, i think i lost 5 pounds peddling around .. i has what appears to be a strong spark, nice and blue. it is getting fuel, had the carb off to make sure no dirt was in the jet. .. would it be possible it is out of time.there is or was no backfire to suggest shearing off a key. im at a loss, it wont even attempt to fire. any ideas?