I'm freshening up a Yammy QT50 that ran fine last year. Battery is good, plug is good, carb is clean. Can't get it to stay running, and once it does start it winds up past "red line". Can only get it started by holding my fingers in front of the intake on the carb. Air filter is M.I.A. Is there any way to get it started without the filter? Gonna spend some time in the garage tonight, any ideas?